***Useful Information For The Working Sparky***

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MINOR ELECTRICAL INSTALLATION WORKS CERTIFICATE

(REQUIREMENTS FOR ELECTRICAL INSTALLATIONS - BS 7671 [IEE WIRING REGULATIONS ) To be used only for minor electrical work which does not include the provision of a new circuit
GUIDANCE FOR RECIPIENTS
This safety Certificate has been issued to confirm that the electrical installation work to which it relates has been designed, constructed, inspected and tested in accordance with British Standard 7671 (the IEE Wiring Regulations).
You should have received an "original" Certificate and the contractor should have retained a duplicate. If you were the person ordering the work, but not the owner of the installation, you should pass this Certificate, or a full copy of it, immediately to the owner.
A separate Certificate should have been received for each existing circuit on which minor works have been carried out. This Certificate is not appropriate if you requested the contractor to undertake more extensive installation work, for which you should have received an Electrical Installation Certificate.
The Certificate should be retained in a safe place and be shown to any person inspecting or undertaking further work on the electrical installation in the future. If you later vacate the property, this Certificate will demonstrate to the new owner that the minor electrical installation work carried out complied with the requirements of British Standard 7671 at the time the Certificate was issued.

PERIODIC INSPECTION REPORT NOTES:
1. This Periodic Inspection Report form shall only be used for the reporting on the condition of an existing installation.
2. The Report, normally comprising at least four pages, shall include schedules of both the inspection and the test results. Additional sheets of test results may be necessary for other than a simple installation. The page numbers of each sheet shall be indicated, together with the total number of sheets involved. The Report is only valid if a Schedule of Inspections and a Schedule of Test Results are appended.
3. The intended purpose of the Periodic Inspection Report shall be identified, together with the recipient’s details, in the appropriate boxes.
4. The maximum prospective fault current recorded should be the greater of either the short-circuit current or the earth fault current.
5. The ‘Extent and Limitations’ box shall fully identify the elements of the installation that are covered by the report and those that are not, this aspect having been agreed with the client and other interested parties before the inspection and testing is carried out.
6. The recommendation(s), if any, shall be categorised using the numbered coding 1-4 as appropriate.
7. The ‘Summary of the Inspection’ box shall clearly identify the condition of the installation in terms of safety.
8. Where the periodic inspection and testing has resulted in a satisfactory overall assessment, the time interval for the next periodic inspection and testing shall be given. The IEE Guidance Note 3 provides guidance on the maximum interval between inspections for various types of buildings. If the inspection and testing reveal that parts of the installation require urgent attention, it would be appropriate to state an earlier re-inspection date, having due regard to the degree of urgency and extent of the necessary remedial work.
9. If the space available on the model form for information on recommendations is insufficient, additional pages shall be provided as necessary.

EXTENT & LIMITATIONS OF THE INSPECTION ( note 5 ) this will come up !!!!
Extent of Electrical Installation covered by this report :
Limitations : ( see Regulation 634.2 )
This inspection has been carried out in accordance with BS-7671:2008 ( IEE Wiring Regulations ) -
Amended to Cables concealed within trunking conduit , or cables & conduits concealed under floors , in roof spaces & generally
Within the fabric of the building or underground have not been inspected ;
( EXTENT & LIMITATIONS , remember this is with the Client ) ←←←←←

PERIODIC INSPECTION REPORT GUIDANCE FOR RECIPIENTS (to be appended to the Report)
This Periodic Inspection Report form is intended for reporting on the condition of an existing electrical installation.
You should have received an original Report and the contractor should have retained a duplicate. If you were the person ordering this Report, but not the owner of the installation, you should pass this Report, or a copy of it, immediately to the owner.
The original Report is to be retained in a safe place and be shown to any person inspecting or undertaking work on the electrical installation in the future. If you later vacate the property, this Report will provide the new owner with details of the condition of the electrical installation at the time the Report was issued.
The ‘Extent and Limitations’ box should fully identify the extent of the installation covered by this Report and any limitations on the inspection and tests. The contractor should have agreed these aspects with you and with any other interested parties (Licensing Authority, Insurance Company, Building Society etc) before the inspection was carried out.
The report should identify any departures from the safety requirements of the current Regulations and any defects, damage or deterioration that affect the safety of the installation for continued use. For items classified as ‘requires urgent attention’, the safety of those using the installation may be at risk, and it is recommended that a competent person undertakes the necessary remedial work without delay.
For safety reasons, the electrical installation will need to be re-inspected at appropriate intervals by a competent person. The maximum time interval recommended before the next inspection is stated in the Report under ‘Next Inspection.’
The Report is only valid if a Schedule of Inspections and a Schedule of Test Results are appended.

Notes on the formal visual and combined inspection and test record (Form VI.2):
1 Register No - this is an individual number taken from the equipment register, for this particular item of equipment.
2 Description of equipment, e.g. lawnmower, computer monitor.
3 Construction Class - Class 0, 0I, I, II, III. Note that only Class I and II equipment may be used without special precautions being taken.
4 Equipment types - portable, movable, hand-held, stationary, fixed, built-in.
5, 6 Insert the location and any particular external influences such as heat, damp, corrosive, vibration.
7, 8 Frequency of inspection - generally as suggested in Table 7.1 of the Code of Practice for In-Service Inspection and Testing of Electrical Equipment. Inspection - items 17-23 and 28 will be completed if an inspection is being carried out. Inspection and Test - the testing in items 24v and 26 should always be preceded by inspection.
9-11 The make, model and serial number of the item of equipment should be inserted.
12-14 The voltage for which the equipment is suitable, the current consumed and the fuse rating should be inserted.
15-16 The date of purchase and the guarantee should be completed by the client
17 The date to be inserted is the date of the inspection or the date of the inspection and testing.
18 Environment and use. It should be confirmed that the equipment is suitable for use in the particular environment and is suitable for the use to which it is being put.
19 Authority is required from the user to disconnect equipment such as computers and telecom equipment - where unauthorised disconnection could result in loss of data. Authority should also be obtained if such equipment is to be subjected to the insulation resistance and electric strength tests.
20 Socket-outlet/flex outlet. The socket or flex outlet should be inspected for damage including overheating. If there are signs of overheating of the plug or socket-outlet, the socket-outlet connections should be checked as well as the plug. This work should only be carried out by an electrician.
21-23 The inspection required is described in Chapter 14 of the Code of Practice for In-Service Inspection and Testing of Electrical Equipment.
24-27 Tests. The tests are described in Chapter 15 of the Code of Practice for In-Service Inspection and Testing of Electrical Equipment. The tests should always be preceded by the Inspection items 17-23 and 28. The instrument reading is to be recorded and a tick entered if the test results are satisfactory.
28 Functional Check - a check is made to ensure that the equipment works properly.
29 Comments/other tests. Additional tests may be needed to identify a failure more clearly or other tests may be carried out such as a touch current measurement. An additional sheet may be necessary, which should be referenced in the box on this record..
30 OK to use - ‘YES’ should be inserted if the item of equipment is satisfactory for use, ‘NO’ if it is not.

 

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1. SELV – an extra-low voltage system which is electrically separated from Earth and from other systems in such a way that a single-fault cannot give rise to the risk of electric shock. The particular requirements of the Regulations must be checked (see Section 414)
2. Double or reinforced insulation. Not suitable for domestic or similar installations if it is the sole protective measure (see 412.1.3)
3. Basic protection – will include measurement of distances where appropriate
4. Obstacles – only adopted in special circumstances (see 417.2)
5. Placing out of reach – only adopted in special circumstances (see 417.3)

6. Non-conducting locations and Earth-free local equipotential bonding – these are not recognised for general application. May only be used where the installation is controlled/under the supervision of skilled or instructed persons (see Section 418)
7. Electrical separation – the particular requirements of the Regulations must be checked. If a single item of current-using equipment is supplied from a single source, see Section 413. If more than one item of current-using equipment is supplied from a single source then the installation must be controlled/under the supervision of skilled or instructed persons, see also Regulation 418.3.

FOR INSPECTION & TESTING
I/We being the person(s) responsible for the inspection & testing of the electrical installation (as indicated by my/our signatures below), particulars of which are described above, having exercised reasonable skill and care when carrying out the inspection & testing hereby CERTIFY that the work for which I/we have been responsible is to the best of my/our knowledge and belief in accordance with BS 7671:2008, amended to ..............................(date) except for the departures, if any, detailed as follows:
Details of departures from BS 7671 (Regulations 120.3 and 120.4):
The extent

FOR CONSTRUCTION
I/We being the person(s) responsible for the construction of the electrical installation (as indicated by my/our signatures below), particulars of which are de-scribed above, having exercised reasonable skill and care when carrying out the construction hereby CERTIFY that the construction work for which I/we have been responsible is to the best of my/our knowledge and belief in accordance with BS 7671:2008, amended to ................................(date) except for the departures, if any, detailed as follows:
Details of departures from BS 7671 (Regulations 120.3 and 120.4):

FOR INSPECTION & TESTING
I/We being the person(s) responsible for the inspection & testing of the electrical installation (as indicated by my/our signatures below), particulars of which are described above, having exercised reasonable skill and care when carrying out the inspection & testing hereby CERTIFY that the work for which I/we have been responsible is to the best of my/our knowledge and belief in accordance with BS 7671:2008, amended to ..............................(date) except for the departures, if any, detailed as follows:
Details of departures from BS 7671 (Regulations 120.3 and 120.4):

FOR DESIGN
I/We being the person(s) responsible for the design of the electrical installation (as indicated by my/our signatures below), particulars of which are described above, having exercised reasonable skill and care when carrying out the design hereby CERTIFY that the design work for which I/we have been responsible is to the best of my/our knowledge and belief in accordance with BS 7671:2008, amended to................................(date) except for the departures, if any, detailed as follows:
Details of departures from BS 7671 (Regulations 120.3 and 120.4):

FOR DESIGN, CONSTRUCTION, INSPECTION & TESTING
I being the person responsible for the Design, Construction, Inspection & Testing of the electrical installation (as indicated by my signature below), particulars of which are described above, having exercised reasonable skill and care when carrying out the Design, Construction, Inspection & Testing, hereby CERTIFY that the said work for which I have been responsible is to the best of my knowledge and belief in accordance with BS 7671:2008 amended to .......... (date) except for the departures, if any, detailed as follows:
Details of departures from BS 7671 (Regulations 120.3 and 120.4):

Amberleaf here , please tell you Mates about this forum : this forum is Here to help Electricians :
There’s “ NOT “ a lot of forum that is doing this , let DAN & and the Boys ← know this , many thanks Amberleaf ,
DAN your Site has the Strength & Convictions to stand up for Electricians : Big Pat on the Back ,

LEVEL 2 CERTIFICATE IN FUNDAMENTAL INSPECTION, TESTING AND INITIAL VERIFICATION OF ELECTRICAL INSTALLATIONS ( GUILDS 2392-10 )

2392
INTRODUCTION
This three day course covers the theory and practice of the fundamental inspection, testing and initial verification of electrical installations and is based on the syllabus laid down in City & Guilds' 2392-10 Scheme Regulations. Its primary objective is to prepare candidates for assessment leading, for successful candidates, to the award of a City & Guilds ‘Certificate in Fundamental Inspection, Testing and Initial Verification 2392-10'.
The course is primarily about the practical application of Part 6 of BS 7671 and participants must be familiar with much of the terminology used in the Regulations and have a good grasp of their technical requirements.
Gaining familiarity with IEE Guidance Note 3 and its content is also an important aspect of the course, and candidates will need to refer to this, and also BS 7671, during the City & Guilds practical assessment.

LEVEL 2 CERTIFICATE IN FUNDAMENTAL INSPECTION, TESTING AND INITIAL VERIFICATION OF
ELECTRICAL INSTALLATIONS

OBJECTIVES
The course embraces:
* Statutory duties and safe working practices
* BS 7671:2008 requirements for inspection, testing and certification
* IEE Guidance Note 3, Inspection & Testing, 5th edition, guidance and recommendations
* Demonstration of tests and 'hands-on' experience

By the end of the Course participants should be fully aware of:
1. The BS 7671 requirements for initial verification, inspection and testing;
2. The information required to correctly conduct the inspection and testing of a new installation;
3. The statutory and non-statutory requirements and relevant guidance material which apply to the activity of inspecting and testing of electrical installations;
4. The information to be contained on forms, i.e. Electrical Installation Certificates, Minor Works Electrical Installation Certificates and how this information should be recorded.

Participants should also be fully prepared for the practical and written assessments City & Guilds 2392-101/102:

A practical assessment (2 hours), normally conducted one week after the course completion date

A multiple-choice GOLA (Global Online Assessment) - 50 questions in 1 hour 40 minutes,

LEVEL 2 CERTIFICATE IN FUNDAMENTAL INSPECTION, TESTING AND INITIAL VERIFICATION OF
ELECTRICAL INSTALLATIONS

Module 1 Includes reference to statutory requirements and safety aspects, and also covers some of the relevant definitions of BS 7671.
Module 2 Reminds participants of some of the relevant technical requirements of other Parts of BS 7671.
Module 3 Explains the inspection requirements of BS 7671 and makes considerable reference to Guidance Note 3. It has an Inspection Assessment at the end during which the participants, are invited to identify faults by inspection. This is an important Module, since City & Guilds place considerable emphasis on inspection in both the practical and assessments in particular the filling in of the Schedule of Inspections
Module 4 Explains the sequence of tests required, dangers of testing and relevant circuit theory.
Module 5 This module covers basic care of instruments and gives candidates the opportunity to familiarise themselves with the low reading ohm-meter, the module also helps to reinforce the theory or the previous module.
Modules 6-8 Are all concerned with testing. During Modules 6 and 8 delegates receive a demonstration on 'dead' and 'live' tests on two identical Demonstration Boards.
Modules 9-11 Are all concerned with testing. During Module10 delegates receive a demonstration on 'dead' and 'live' tests on two identical Demonstration Boards.
Module 12 Covers certification and reporting. LEVEL 2 CERTIFICATE IN FUNDAMENTAL INSPECTION, TESTING AND INITIAL VERIFICATION OF ELECTRICAL INSTALLATIONS (CITY & GUILDS 2392-10) 2392

General Introduction
Module 1: Preparation for Inspection, Testing and Certification
Module 2 - BS 7671 reinforcement
Module 3 - Inspection of Installations
Module 4 - Introduction to Testing
Module 5 – Low Reading Ohm-meter
Module 6 - Testing (1) Methodology
Module 7 - Testing (1) Practical
Module 8 – Testing (2) Methodology
Module 9 - Testing (2) Practical & Fault Finding
Module 10 – Testing (3) Methodology
Module 11 – Testing (3) Practical
Module 12 - Certification and Reporting

2392-10 PS : Electricians that have NOT Done Testing for a “ Long Time “ I would “ Recommend “ that you Do the 5 DAYS COARSE , And a LOT of Studying , take it for me , its Not a Walk in the Park : If you do the 3 Day Coarse , when you come to the EXAM you head will be up your But big Time !!! Trust me one this One ,
Remember that you have three Days to take that all in : ←
Third day : your on the Boards Testing then , before you Know it doing the Exam !!!!!!!

 

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2392-10 Electricians :
Part P of the Building Regulations for England and Wales was introduced by the government in January
2005, with an aim of reducing the number of accidents in the home related to faulty electrical installations. Similar laws apply in Scotland. It is now a legal requirement for electricians, kitchen, bathroom and gas installers, and all other trades or individuals involved in carrying out domestic electrical installation work to comply with Building Regulations.

Most electrical installations carried out in a property are now notifiable: in other words the local authority
building control must be notified prior to the work being carried out. The exception is if it is carried out, inspected and certified by a person registered with a government-authorised competent person scheme such as NICEIC. Failure to comply with Part P is a
criminal offence and local authorities have the power to require the removal or alteration of work that does not comply with the regulations.

You are advised to have a property maintenance and appliance testing procedure in place. This should
ensure properties are maintained in a safe condition.
1 Carry out regular visual inspections, looking for obvious signs of damage such as scorch marks on
socket outlets and damaged cables :
2 Get the property inspected and tested by a competent person on change of occupancy, or at least every 10 years :
3 Ensure formal inspection and testing more often in higher risk properties where the installation is very old, or where damage has been found in the past
4 Carry out regular inspections on all electrical appliances
Inspection Electrical Appliances :
The Department of Trade and Industry (DTI) strongly advises estate agents, letting agents, landlords and anyone else who lets furnished accommodation to seek independent advice as to who is responsible for the safety of electrical appliances supplied in the course of business.
If you are a landlord and provide any electrical appliances (cookers, kettles, toasters, washing machines, immersion heaters, etc) as part of the tenancy, the Electrical Equipment (Safety) Regulations 1994 requires that you ensure the
appliances are safe to use when first supplied. Each time the property is relet, it will be classed as supplying to that tenant for the first time. So you need to:
Check appliances for signs of damage:
1 cuts or abrasions to the cable covering
2 cracked casing or bent pins
3 loose parts and screws
4 overheating (burn marks)
5 the outer covering of the cable not being gripped where it enters the plug or equipment. Look to
see if the coloured insulation of the internal wires is showing :
* You may need to carry out a formal inspection. It should include removal of the plug cover to check:
1 the cord grip is holding the outer part of the cable tightly :
2 the wires, including the earth wire where fitted are attached to the correct terminals :
3 no bare wire is visible other than at the terminals :
4 the terminal screws are tight
5 there is no sign of internal damage, overheating or entry of liquid, dust or dirt Most of these checks apply to extension leads and their plugs and sockets. But some faults cannot be detected in this way, such as lack of continuous earths, which for some equipment, is essential for safety. All earthed equipment should have an occasional combined inspection and test to look for faults. Combined inspection and testing should be
carried out where there is reason to suspect the equipment may be faulty or damaged or
contaminated, but where this cannot be confirmed by visual inspection. Combined testing should also be
carried out after any repair or similar work to the equipment :
Extension Leads Warning :
Use of extension leads should be avoided where possible. If used, they should be tested as portable
appliances. It is recommended that 3-core leads ( including a protective earthing conductor) be used.
A standard 13 amp, 3-pin extension socket outlet with a 2-core cable should never be used even if the
appliance is Class II (music system, TV and video), as it would not provide protection against electric shock
if used at any time with an item of Class I ( cookers, washing machines, refrigerators, irons, dishwashers ).
Portable Equipment Outdoors :
In domestic premises, all socket outlets, which may be used for portable equipment outdoors, should be
protected by an RCD (a safety device that switches off the electricity automatically when it detects an
earth fault) to provide protection against electric shock . Socket outlets installed below kitchen worktops may
usually be considered to be unavailable for connection of outdoor portable equipment, and
would therefore not be required to be RCD protected. It is wise to exclude socket outlets intended for refrigerators and freezers from circuits which require sensitive RCD protection .
Contractors are assessed against the national standard for the safety of electrical installations,
British Standard BS 7671: Requirements for electrical installations (also known as the IEE Wiring Regulations). They must also comply with the electrical safety requirements of any other applicable Codes of Practice, such as those for fire alarms, emergency lighting. In England and Wales, it is a legal requirement for electrical work carried out in and outside the home to comply with Part P of the Building Regulations.

2392-10 Domestic Electrician : ↑↑↑↑ If you are a landlord, you need to be sure that the electrics in your property or properties are safe. That’s the law.
Dozens of people die and thousands are injured every year through unsafe electrics. If you let property, take note of these statistics – rented properties are potentially more at risk than owner-occupier homes as they tend to get more
wear and tear. Identifying faulty electrical installations can be difficult. Especially in rented properties as tenants
may have carried out electrical work themselves without requesting permission or notifying their landlord. An accident could be waiting to happen, and the electrical installation in one of your houses or flats may not comply with national safety standards and Building Regulations.
( IF your got to send a Note to a Landlord , here it is ) your “ But “ is Covered :

Apprentice Question 1 :
Assessment of general characteristics would not include :
Choose one answer.
(A) Purpose for which the installation is intended to be used
(B) External influences
(C) Length of final circuit cable runs *
(D) Compatibility of equipment
Question 2 :
Where the provision of safety services is required the supply characteristics for the safety services or systems shall be:
Choose one answer.
(A) AC only
(B) Separately assessed *
(c) DC only
(D) Exactly the same as the incoming supply characteristics
Question 3
Characteristics of supply shall be determined by:
Choose one answer.
(A) Inspection
(B) Measurement
(C) Enquiry and calculation
(D) Calculation, measurement, enquiry or inspection *

Question 4 :
When determining maximum demand of an installation:
(A) All circuit breakers and fuse ratings within the installation must be added together
(B) All circuits must be fully loaded
(C) A clip on ammeter must be used during low demand periods
(D. Diversity may be taken into account *
Question 5 :
Every installation shall be divided into circuits as necessary in order to:
(A) Reduce running costs
(B) Reduce final circuit cable lengths
(C) Facilitate inspection and testing and maintenance *
(D) Minimise installation time
Question 6 :
Assessment of general characteristics would include:
(A) Maintainability, safety services and continuity of service *

(B) Cost of installation
(C) Number of distribution boards and or consumer units
(D) Total floor area

 

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17th Edition Forms :
1 Initial inspection and testing

Forms 1 to 4 are designed for use when inspecting and testing a new installation, or an alteration or addition to an existing installation. The forms comprise the following:
1 Short form of Electrical Installation Certificate (To be used when one person is responsible for the design, construction, inspection and testing of an installation.)

2 Electrical Installation Certificate (Standard form from Appendix 6 of BS 7671)
3 Schedule of Inspections
4 Schedule of Test Results.
Notes on completion and guidance for recipients are provided with the form.

2 Minor works :
The complete set of forms for initial inspection and testing may not be appropriate for minor works. When an addition to an electrical installation does not extend to the installation of a new circuit, the minor works form may be used. This form is intended for such work as the addition of a socket-outlet or lighting point to an existing circuit, or for repair or modification.
Form 5 is the Minor Electrical Installation Works Certificate from Appendix 6 of BS 7671.
Notes on completion and guidance for recipients are provided with the form.

3 Periodic inspection :
Form 6, the Periodic Inspection Report from Appendix 6 of BS 7671, is for use when carrying out routine periodic inspection and testing of an existing installation. It is not for use when alterations or additions are made. A Schedule of Inspections (3) and Schedule of Test Results (4) should accompany the Periodic Inspection Report (6).
Notes on completion and guidance for recipients are provided with the form.

Electrical Protection : Apprentices ,
“ Isolation and Cutting Off Supply “
(a) Does every machine have a means of isolation provided and is it accessible ?
(b) Does every machine have a means by which it can be stopped, e.g. a stop button and is this button of the mushroom head type and easily accessible?
(c) Are isolators in good condition and can the be operated without difficulty? For example, check for broken handles or any impediment in the operation?
(d) Is the system provided with adequate means of isolation back at the mains switchroom and at the respective distribution points? Does every machine have a means of isolation?
(e) Are all the isolation points clearly marked for the circuits they control? Identification is very important and should be looked for in every inspection. This should also include identification of fuse ways within distribution boards and at front and rear of switchboards.
(f) Check to ensure that all circuits have a means of switching off, e.g. lighting and fan switches and are these in good working order and not broken ?
(g) Ask about OFF LOAD isolation and the procedures existing for operation of such...
who does it and by which methods ?
“ Earthing “
Note: visual examinations of the earthing arrangements.
(a) All conductive parts, i.e. metallic enclosures, pipes, radiators, taps etc., must be bonded and efficiently connected to earth.
(b) Check this carefully and if the earthing protective conductor is visible, examine the connections for tightness. They must be as tight as possible, because loose or slack connections give a high resistance and result in danger.
(c) Check colour coding of the earthing protective conductor; this should be green/yellow. 514.3 / 514.4.2
(d) Is the conductor large enough to carry fault currents without destruction ?
(e) How often is the EARTH FAULT IMPEDANCE tested and what are the latest results ?
(f) Is armouring, conduit or trunking used as the earth protective conductor? Check glands for tightness, look for signs of corrosion and damage ,
(g) Ask about the earthing system... do they obtain this from the Supply Authority and how, or do they have an earth rod or a water pipe ? 411.3.1.2
“ Portable Tools “
Note 1: The safest voltage is the lowest practicable voltage. Generally the recommended voltage is 110 volts AC from a step down transformer where the mid point of the secondary 110 volt winding is connected to earth ( CTE ). This limits the shock to earth voltage to 55 volts AC. In confined conducting locations the voltage should be much lower than this, i.e. no more than 50 volts from an unearthed ( or isolated earth ) supply, or 50 volts from a ( CTE ) supply to give a 25 volt shock-earth.
(b) Check the cables and entries, are they damaged?
(c) Are there any taped joints. If so have them replaced ,
(d) Check to see if the metal casing or any other metallic parts of the tool are sufficiently earthed.
Note 2: Double insulated or all insulated (Class II) tools do not require an earth. It is therefore vitally
important to ensure that the casing, cable insulation and plug are not damaged.
(e) If the tool has to be supplied from a 230 volt AC supply ask for RCD (30mA trip) protection.
(f) Are they inspected, tested and maintained regularly ?
(g) Check plugs, fuses, cables and general conditions .
“ Adverse Environmental Conditions “
(a) Firstly, check the environment, i.e. is it:
• Dusty.
• Wet or damp (do they use hosing down operations).
• Corrosive.
• Dirty.
• Adverse weather or just simple weather exposure.
• High temperatures and/or pressures.
• Flammable or explosive atmospheres.
Note: Standard electrical equipment will be seriously affected by these conditions and danger will result. Electrical equipment will have to be selected accordingly to suit the environment so as to combat the consequential problems. There are many British Standards dealing with the requirements for electrical equipment in adverse atmospheres and these should be consulted along with specialist advice.
(b) Check the type of installed equipment against the environment and advise accordingly:
• Dirty, dusty, wet, adverse weather – BS-EN60529.
• Flammable/Explosive areas – BS-EN60079.
• Corrosion – Replace or clean down and repaint with anti-corrosive paint.
• High temperature, pressures – Reposition or replace with suitable equipment.
(c) Check also the installation medium such as cables, conduits etc. It is better to use armoured cables or MICC cables in most environments.

2392-10 Traditional Junction Boxes : ( Regulation 526.3 p-106 : BS-EN60670-22 – BS 6220
unless using a solution such as maintenance free terminals, the access to electrical connections should be
adequate for their safe and proper inspection, testing and maintenance. In this respect, connections should be in a location where they can reasonably be reached and where there is adequate working space.:

Where connections are made in roof spaces and inter-floor spaces the enclosures containing the connections should normally be fixed and provision must be made for their access. Providing these two constraints are complied with, then the
continued use of standard circular junction boxes remains acceptable.

Maintenance Free Connections
Maintenance free terminals provide one solution where accessibility is an issue :

Junction boxes are commonly used during alterations and additions to an installation. With certain exceptions regulation 526.3 requires that every connection shall be accessible for inspection, testing and maintenance.
The Electrical Safety Council Technical Manual states that “a junction box with screw terminals is an example of where connections must be accessible”. The reason is to allow inspection of joints which could have relaxed or loosened over time, a recognised problem with screwed terminals.
Unless provision is made for access, where boarding, carpet or other similar covering is laid over a junction box with screw terminals, it may not be considered accessible and maintenance free terminals should be used.
This is further reinforced in Appendix 15 of the Wiring Regulations which states “Junction boxes with screw terminals must be
accessible for inspection, testing & maintenance or, alternatively, use maintenance-free terminals / connection (Regulation 526.3)”

Junction boxes with screw terminals must be accessible for inspection...

 

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SCHEDULES ******
The attached Schedules are part of this document and this Certificate is valid only when they are attached to it.
............ Schedules of Inspections and ............ Schedules of Test Results are attached. (Enter quantities of schedules attached).

( C&G 2392-10 ) ( 2 days plus 1 day Assessments )
This new qualification has been developed in order to meet the needs of the electrical contracting industry.
It is intended to provide candidates with an introduction to the fundamentals of inspection, testing and initial verification of electrical installations.
It is aimed at practicing electricians who have not carried out inspection and testing since qualifying or who require some update training.
It is also suitable for those coming into the industry with limited experience of inspection and testing.
Candidates who achieve this qualification could progress onto the Certificate in Inspection, Testing and Certification of Electrical Installations (2391-10).

SCHEDULE OF TEST RESULTS

NOTES ON SCHEDULE OF TEST RESULTS :
Type of supply is ascertained from the distributor or by inspection :
( Ze at origin.) When the maximum value declared by the distributor is used, the effectiveness of the earth must be confirmed
Prospective fault current (PFC). The value recorded is the greater of either the short-circuit current or the earth fault current
Preferably determined by enquiry of the distributor

Short-circuit capacity of the device is noted, see Table 7.2A of the On-Site Guide or Table 2.4 of GN3

the following tests, where relevant, shall be carried out in the following sequence :
Continuity of protective conductors, including main and supplementary bonding
Every protective conductor, including main and supplementary bonding conductors, should be tested to verify that it is continuous and correctly connected :

Continuity :
Where Test Method 1 is used, enter the measured resistance of the line conductor plus the circuit protective conductor ( R1 + R2 )
See 10.3.1 of the On-Site Guide or 2.7.5 of GN3, During the continuity testing (Test Method 1) the following polarity checks are to be carried out:
(a) every fuse and single-pole control and protective device is connected in the line conductor only
(b) centre-contact bayonet and Edison screw lampholders have outer contact connected to the neutral conductor
c) wiring is correctly connected to socket-outlets and similar accessories. Compliance is to be indicated by a tick in polarity column 11
(R1 + R2 ) need not be recorded if ( R2 is recorded in column 7 :


Where Test Method 2 is used, the maximum value of ( R2 ) is recorded in column 7.
See 10.3.1 of the On-Site Guide or 2.7.5 of GN3

Continuity of ring final circuit conductors :
A test shall be made to verify the continuity of each conductor including the protective conductor of every ring final circuit
See 10.3.2 : of the On-Site Guide or 2.7.6 of GN3 :

Insulation Resistance
All voltage sensitive devices to be disconnected or test between live conductors (line and neutral) connected together and earth
The insulation resistance between live conductors is to be inserted in column 9
The minimum insulation resistance values are given in Table 10.1 of the On-Site Guide or Table 2.2 of GN3
See 10.3.3 (iv) of the On-Site Guide or 2.7.7 of GN3

All the preceding tests should be carried out before the installation is energised :
Polarity :
A satisfactory polarity test may be indicated by a tick in column 11
Only in a Schedule of Test Results associated with a Periodic Inspection Report is it acceptable to record incorrect polarity ,

Earth fault loop impedance Z
This may be determined either by direct measurement at the furthest point of a live circuit or by adding (R1 + R2 ) of column 6 to
Ze . is determined by measurement at the origin of the installation or preferably the value declared by the supply company used
Zs = Ze + ( R1 + R2 ) Zs should be less than the values given in Appendix 2 of the On-Site Guide or Appx 2 of GN3

functional testing :
The operation of RCDs (including RCBOs) shall be tested by simulating a fault condition, independent of any test facility in the device
Record operating time in column 13. Effectiveness of the test button must be confirmed
See Section 11 of the On-Site Guide or 2.7.15 and 2.7.18 of GN3

All switchgear and controlgear assemblies, drives, control and interlocks, etc must be operated to ensure that they are properly
mounted, adjusted, and installed Satisfactory operation is indicated by a tick in column 14
Earth electrode resistance
The earth electrode resistance of TT installations must be measured, and normally an RCD is required
For reliability in service the resistance of any earth electrode should be below 200 Ω. Record the value on Form 1, 2 or 6, as
appropriate. See 10.3.5 of the On-Site Guide or 2.7.12 of GN-3

NOTES ON COMPLETION OF MINOR ELECTRICAL INSTALLATION WORKS CERTIFICATE

Scope
The Minor Works Certificate is intended to be used for additions and alterations to an installation that do not
extend to the provision of a new circuit. Examples include the addition of socket-outlets or lighting points to
an existing circuit, the relocation of a light switch etc. This Certificate may also be used for the
replacement of equipment such as accessories or luminaires, but not for the replacement of
distribution boards or similar items. Appropriate inspection and testing, however, should always be carried out irrespective of the extent of the work undertaken ,

Part 1 Description of minor works :

1,2 : The minor works must be so described that the work that is the subject of the certification can be readily identified.
4 See Regulations 120.3 and 120.4. No departures are to be expected except in most unusual circumstances. See also Regulation 633.1

Part 2 Installation details :
2 : The method of fault protection must be clearly identified e.g. earthed equipotential bonding and automatic disconnection of supply using fuse/circuit-breaker/RCD.
4 : If the existing installation lacks either an effective means of earthing or adequate main equipotential bonding conductors, this must be clearly stated. See Regulation 633.2
Recorded departures from BS-7671 may constitute non-compliance with the Electricity Safety, quality and continuity Regulations 2002 (as amended) or the Electricity at Work Regulations 1989. It is important that the client is advised immediately in writing.
Part 3 Essential Tests :
The relevant provisions of Part 6 ( Inspection and Testing ) of BS 7671 must be applied in full to all minor
works. For example, where a socket-outlet is added to an existing circuit it is necessary to:
1 : establish that the earthing contact of the socket-outlet is connected to the main earthing terminal
2 : measure the insulation resistance of the circuit that has been added to, and establish that it complies with Table 61 of BS 7671
3 : measure the earth fault loop impedance to establish that the maximum permitted disconnection time is not exceeded
4 : check that the polarity of the socket-outlet is correct
5 : (if the work is protected by an RCD) verify the effectiveness of the RCD
Part 4 Declaration :
1.3 : The Certificate shall be made out and signed by a competent person in respect of the design construction, inspection and testing of the work.
1,3 The competent person will have a sound knowledge and experience relevant to the nature of the
work undertaken and to the technical standards set down in BS-7671 be fully versed in the inspection
and testing procedures contained in the Regulations and employ adequate testing equipment.
2 : When making out and signing a form on behalf of a company or other business entity, individuals shall state for whom they are acting.

 

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About the Electrical Testing and Inspection
During the inspection, you can rest assured that we will cover the most obvious danger points and those that are less obvious, including:
• System types
• Live conductors
• Nature of supply parameters
• Supply protective device characteristics
• Means of earthing
• Details of installation earth electrode
• Main switch circuit breaker
• Main protective conductors
• Bonding of extraneous conductive parts
• Method of protection against indirect contact
• Method of protection against electrical shock
• Prevention of mutual detrimental influence
• Protection against indirect contact
• Cables and conductors
• Circuits
• Boards
Emergency Lighting Testing BS 5266
Emergency lighting is required in all premises where people are employed and it is a mandatory requirement to be installed where artificial lighting is installed.

Under the “Fire Precaution (Workplace) Regulations 1999” all Employers, Landlords or Occupiers have a duty to carry out a risk assessment to ensure their premises and activities are able to facilitate safe escape in the event of an emergency.
The Emergency Lighting British Standard BS5266 defines the requirements for the correct installation of Emergency Lighting. Compliance with this standard will ensure that your premises, meets the requirements of the Fire Precaution (Workplace) Regulations.

BS5266 requires inspection & tests should be carried out at the following intervals (Frequencies);

Daily
Monthly
Six-Monthly
Three Yearly
Subsequent Annual Test

Portable Appliance ( Pat Testing )
The law clearly states that all employers have a legal obligation to maintain all electrical equipment in order to ensure a safe working environment. This includes all electrically operated items such as computers, printers, photocopiers, kettles, extension leads, vacuums etc.
Organisations of all types and sizes have a duty to protect their employees and business from this risk and to comply with the Electricity at Work Regulations 1989, Health and Safety at Work Act 1974, The Electrical Equipment (Safety) Regulations 1994, Provision and Use of Work Equipment Regulations 1998
• Replacement of faulty or damaged mains plug (BS1363/A)
• Replacement of damaged or incorrectly rated fuses (BS1362)
• Re-wiring of incorrect connections in the mains plug BS1363/A)
• Repair to faulty cable grips in the mains plug BS1363/A)
• Minor repairs requiring less than ten minutes labour
• Re-test following repair

All Appliances are labelled with the result of the test (pass or fail).

Description of Minor Works :

The minor works must be so described that the work that is the subject of the certification can be readily identified.
See Regulations 120.3 ) This Standard sets out Technical Requirements intended to ensure that Electrical Installations conform to
The Fundamental Principles chapter 13 : as follows , ( Part 3 ) ( Part 4 ) ( Part 5 ) ( Part 6 ) ** ( Part 7 ) ** and 120.4. No departures are to be expected except in most unusual circumstances. See also Regulation 633.1 ,
633.1 : Additions & Alterations , this Requirement of Sections 631 & 632 for the issue of an Electrical Installation Certificate or a
Minor Electrical Installation Works Certificate shall apply to all the work of the Additions or Alterations ,

 

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“ Operation of Overload and Fault Current Devices “

When a fault is noticed , it is usually because a circuit or piece of equipment has stopped working and this is usually because the protective device has done its job and operated , the rating of a protective device should be greater than , or at least equal to , the rating of the circuit or equipment it is protecting , e.g. 10 x 100 watt lamps equate to a total current use of 4.35 amperes ,
Therefore a device rated at 5 or 6 amperes could protect this circuit ,
A portable domestic appliance which has a label rating of 2.7kW equates to a total current of 11.74 amperes ,
Therefore a fuse rated at 13 amperes should be fitted in the plug ,
Protective devices are designed to operate when an excess of current ( greater than the design current of the circuit )
Passes through it , the fault currents excess heat can cause a fuse element to rupture or the device mechanism to trip ,
Dependent on which type of device is installed , these currents may not necessarily be circuit faults , but short-lived overloads specific to a piece of equipment or outlet , the regulations categorise these as overload current & overcurrent , For conductors ,
The rated value is the current-carrying capacity , most excess currents are , however , due to faults , either earth faults or short circuit type which cause excessive currents , whichever type of fault occurs the designer should take account of its effect on the installation wiring and choose a suitable device to disconnect the fault quickly and safely , the fundamental effect of any fault is a rise in current and therefore a rise in temperature , high temperature destroys the properties of installation , which in itself could lead to a short circuit , high currents damage equipment , and earth fault currents are dangerous to the body from electric shock ,
“ Overloads faults “
Adaptors used in socket outlets exceeding the rated load of circuit :
Extra load being added to an existing circuit or installation :
Not accounting for starting current on a motor circuit :
“ Short circuit faults “
Insulation breakdown :
Severing of live circuit conductors :
Wrong termination of conductors energised before being tested :
“ Earth faults “
Insulation breakdown :
Incorrect polarity :
Poor termination of conductors :
“ fuse holder has melted due to overloading “
“ wrong type of starter in fluorescent tube has melted due to excess power demand “
“ poor termination of ( CPC ) circuit protective conductors “ in junction boxes “

Definitions :
“ Overloads current “ – an overcurrent occurring in a circuit which is electrically sound :
“ Overcurrent ” – a current exceeding the rated value
“ Earth fault current “ – a fault current which flows to earth :
“ Short circuit current “ – an overcurent resulting from a fault of negligible impedance between live conductors :

 

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“ Basic electricity “ Apprentice :
All questions about the nature of electricity lead to the composition of matter. All matter is made up of atoms.
Every atom has a nucleus, with positively - charged protons, and neutrons with no charge.
Moving around the nucleus are negatively -charged electrons.
With equal numbers of protons and electrons, their charges cancel each other out, leaving the atom with no overall charge.
An excess of electrons gives an atom a negative charge; a deficiency gives it a positive charge.
In some materials, there are electrons called free electrons, only loosely held by the nucleus.
The more free electrons a material has, the better it can conduct electricity.
Metals typically have lots of free electrons and are good conductors.
In insulators, electrons are bound much more tightly to the nucleus.
They cannot easily move freely, so they are not readily available for electric current.
Semiconductors conduct electricity more easily than insulators but not as well as conductors. They are crucial in electronics

Free electrons

Free electrons are necessary for electric current, but for those electrons to move, they need a complete pathway, or circuit, and there must be a force to make them move. The force from a battery sets free electrons moving.
Like charges repel, so the negative electrons are repelled from the negative terminal. Unlike charges attract, so the electrons are also attracted towards the positive terminal.
They flow in one direction only. This is called direct current or DC. Most circuits in motor vehicles use direct current.
The larger the charge at the positive terminal, the more strongly it attracts free electrons. This attraction acts as a force driving the electrons along. The greater the force, the stronger the electrical current. The force is called electromotive force or EMF. It’s also known as "voltage".
Also affecting the current flow in a circuit is electrical resistance, measured in ohms. All materials have resistance - even good conductors.
Four factors determine the level of resistance:
• Type of material - whether it has enough free electrons;
• Length of the conductor - as length increases, so does resistance;
• Size of the conductor - the larger the conductor, the greater the amount of current it can carry; and
• Temperature of the conductor.
The higher the temperature, the harder it is for electrons to pass through it and the higher the resistance. While all materials have some resistance to current flow, a resistor is a component designed to cause a particular voltage drop in a circuit. It has a set resistance, usually marked or coded on its surface.
Since electric current is the flow of electrons, it's natural to say the direction of current is the direction in which electrons move. However, before the discovery that electric current was the flow of electrons, it was thought the natural way for electricity to move was from positive to negative.
Both concepts are still in use. Current said to flow from positive to negative, is called conventional current. Current said to flow from negative to positive, is called electron current.

Resistance
Electrical resistance is a measure of the degree to which an object opposes the passage of an electric current. The SI unit of electrical resistance is the ohm. Its reciprocal quantity is electrical conductance measured
Resistance is defined as the ratio of the potential difference (i.e. voltage) across the object (such as a resistor) to the current passing through it:
R = V / I
where
• R is the resistance of the object
• V the potential difference across the object, measured in volts
• I is the current passing through the object, measured in amperes
For a wide variety of materials and conditions, the electrical resistance does not depend on the amount of current flowing or the amount of applied voltage. This means that voltage is proportional to current and the proportionality constant is the electrical resistance. This case is described by Ohm's law and such materials are described as ohmic. V can either be measured directly across the object or calculated from a subtraction of voltages relative to a reference point. The former method is simpler for a single object and is likely to be more accurate. There may also be problems with the latter method if the voltage supply is AC and the two measurements from the reference point are not in phase with each other.

Electromagnetic induction

When a conductor cuts across a magnetic field, current flows in the conductor. It flows one way when the conductor cuts the field in one direction, then reverses as it cuts the field in the opposite direction.
The current is called alternating, because it flows one way, and then the other. The term alternating current is often shortened to AC. That's the sort of electrical energy that comes through power outlets. It's also produced by an alternator, as the name indicates.
Moving a wire inside a magnetic field produces a current flow. Similarly, moving a magnet inside a stationary coil of wire, produces the same effect.
If a magnet is rotating in an iron yoke, and a coil of wire is wound around the stem of the yoke to form a complete circuit with the ammeter, this will indicate if current flows.
As the magnet rotates, the ammeter deflects for current flow. For every half-revolution, current flow reverses. Increasing the speed of the magnet increases the amount of electrical energy produced. Electromagnetic induction is applied in alternators and ignition coils.
Electromagnetic induction is the production of an electrical potential difference (or voltage) across a conductor situated in a changing magnetic flux.
Michael Faraday is generally credited with having discovered the induction phenomenon in 1831 though it may have been anticipated by the work of Francesco Zantedeschi in 1829. Faraday found that the electromotive force (EMF) produced along a closed path is proportional to the rate of change of the magnetic flux through any surface bounded by that path. In practice, this means that an electrical current will flow in any closed conductor, when the magnetic flux through a surface bounded by the conductor changes. This applies whether the field itself changes in strength or the conductor is moved through it. Electromagnetic induction underlies the operation of generators, induction motors, transformers, and most other electrical machines.

Electromagnetism
Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field. The electric field can be produced by stationary electric charges, and gives rise to the electric force, which causes static electricity and drives the flow of electric current in electrical conductors. The magnetic field can be produced by the motion of electric charges, such as an electric current flowing along a wire, and gives rise to the magnetic force one associates with magnets. The term "electromagnetism" comes from the fact that the electric and magnetic fields are closely intertwined, and, under many circumstances, it is impossible to consider the two separately. For instance, a changing magnetic field gives rise to an electric field; this is the phenomenon of electromagnetic induction, which underlies the operation of electrical generators, induction motors, and transformers. The term electrodynamics is sometimes used to refer to the combination of electromagnetism with mechanics. This subject deals with the effects of the electromagnetic field on the mechanical behavior of electrically charged particles.

Electromagnetic force
The force that the electromagnetic field exerts on electrically charged particles, called the electromagnetic force, is one of the four fundamental forces. The other fundamental forces are the strong nuclear force (which holds atomic nuclei together), the weak nuclear force (which causes certain forms of radioactive decay), and the gravitational force. All other forces are ultimately derived from these fundamental forces. However, it turns out that the electromagnetic force is the one responsible for practically all the phenomena one encounters in daily life, with the exception of gravity. Roughly speaking, all the forces involved in interactions between atoms can be traced to the electromagnetic force acting on the electrically charged protons and electrons inside the atoms. This includes the forces we experience in "pushing" or "pulling" ordinary material objects, which come from the intermolecular forces between the individual molecules in our bodies and those in the objects. It also includes all forms of chemical phenomena, which arise from interactions between electron orbital’s.

 

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Electrical power

Energy is the potential to do work. But work is done only when the energy is released.
A disconnected battery isn't doing work, but it has the potential to do work, so it's a source of energy.
The difference in electron supply at the battery terminals is sometimes called the potential difference - in the case of a standard charged automotive battery, a potential of 12 volts. Tapping this potential means turning one form of energy, the battery's electrochemical energy, into another.
Turning one form of energy into another is called work.
The amount of energy transformed is the amount of work done. When a person's legs turn the pedals of a bicycle, physical energy is being turned into mechanical energy. A power drill turns electrical energy into mechanical energy.
In each case, work is being done, but the power drill is different - it does the work quicker, delivering more mechanical energy. That difference is called Power. Power is the rate at which work is done. The rate of transforming energy. In an electrical circuit, power refers to the rate at which electrical energy is transformed into another kind of energy
The unit of power is the watt. 1 watt is produced when 1 volt causes a current flow of 1 amp. From this comes the power equation: P, the power in watts, equals V, the voltage in volts, multiplied by I, the current in amps.
This calculation is applied just like Ohm's law.
When current flows in a circuit with a resistor in it, the resistor may become hot as it converts electrical energy into heat energy. If this circuit is powered by a 12 volt battery with a current of 2 amps, using the power equation (P=VxI), we can determine that 24 watts of power are being taken from the circuit by the resistor
It is also possible to simplify and transpose the power equation:
• Power equals voltage times current
• Therefore, voltage equals power divided by current
• and current equals power divided by voltage.

Instantaneous electrical power
The instantaneous electrical power P delivered to a component is defined as:
P = I x V where
• P is the instantaneous power, measured in watts
• V is the potential difference (or voltage drop) across the component, measured in volts
• I is the current flowing through it, measured in amperes
If the component is a resistor, then:
P = I2 x R or
P = V2 ÷ R
where
R is the resistance, measured in ohm.

Parallel circuits

In a series circuit, components are connected like links in a chain. If any link fails, current to all the components is cut off.
In a parallel circuit, all components are connected directly to the voltage supply. If any connection or component fails in a parallel circuit, current continues to flow through the rest.
This is one reason why parallel circuits are used in automotive applications like lighting systems. If one lamp fails, current continues to flow through the rest. In a series circuit, all would go out, which could be disastrous.
Also, since all components connect directly to the battery terminals, the metal of the vehicle’s body can become one of the conductors. One terminal of the battery, and one of each component, can be connected anywhere on the body or chassis, to complete the circuit. This is called an earth, or ground connection. It saves a lot of connecting wire.
A feature of a parallel circuit is that the voltage across each component is the same as battery voltage.
No matter how many components are added, or removed, as long as they’re in parallel, the voltage across them will be the same as across each other component, including the battery.
Another feature of a parallel circuit is that the current flowing in each branch is determined by the resistance of that branch.
In a parallel circuit where the resistors in each branch are the same, the current flowing in each branch is therefore also the same. However, the sum of their individual currents is equal to the total current flowing in the circuit.
When the resistance's are not equal, then the current divides in accordance with the value of each resistance, but the total current flow is still the sum of the currents flowing in each branch.

Parallel circuit resistance Say you have a 12 volt parallel circuit with three branches, each with a 12 ohm resistor, and a current flow of 3 amperes. If you add another 12 ohm resistor to the circuit it produces an effect which is the opposite of what might be expected. Current increases from 3 amperes to 4.

This is because, in a parallel circuit, adding more branches provides more pathways, but decreases the overall circuit resistance, so current flow increases.

Total resistance of a parallel circuit is found by turning all the resistances upside down, to make fractions called reciprocals. In this case, each 12 becomes 1/12th.

The 4/12ths are added together, and the answer turned back up the way it was, so that it is 12/4, or 12 divided by 4, which equals 3. 3 ohms is therefore the total resistance in the circuit. Ohm’s law confirms the ammeter reading of 4 amperes. Now, if 2 resistors are removed, what is the result?

1/12th plus 1/12th is 2/12th’s, which, turned back the way it was, is 12 over 2, or 6 ohms. Voltage across the components is still 12 volts, but by Ohm’s law, the new current is 2 amperes. So removing the resistors, in this circuit, halves the current.

Wire sizing Wire size is very important for the correct operation of electrical circuits. Selecting too small a gauge wire for an application will adversely effect the operation of the circuit. This will cause voltage drop and poor performance, or, in extreme cases, the cable will get hot enough to melt the insulation. Selecting too large a gauge increases costs and weight.

The resistance of a cable affects how much current it can carry. The resistance of a cable is determined by its length and its diameter.

The longer the cable and the smaller the diameter, the higher the resistance. The shorter the cable and the larger the diameter the lower the resistance.

To select the correct cable gauge for any given application it is best to refer to a cable chart. Manufacturers and standards bodies use cable gauge charts to define how much current each cable gauge can carry safely and effectively.

Over the years a number of different wire gauges have been used to determine application.

The primary wire gauges are the metric wire gauge and the American wire gauge or AWG.

For example, this 12 Volt circuit is designed for a maximum current flow of 10 Amps. Because of the installation design, the length of the cable used to wire the circuit needs to be approximately 20 feet or 7 meters in length, so using the AWG table as a reference we see that the correct gauge cable to use is 16AWG.

 

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GUIDANCE FOR RECIPIENTS
This safety Certificate has been issued to confirm that the electrical installation work to which it relates has been designed, constructed, inspected and tested in accordance with British Standard 7671 (the IEE Wiring Regulations).
You should have received an "original" Certificate and the contractor should have retained a duplicate. If you were the person ordering the work, but not the owner of the installation, you should pass this Certificate, or a full copy of it including the schedules, immediately to the owner.
The Certificate should be retained in a safe place and be shown to any person inspecting or undertaking further work on the electrical installation in the future. If you later vacate the property, this Certificate will demonstrate to the new owner that the electrical installation complied with the requirements of British Standard 7671 at the time the Certificate was issued. The Construction (Design and Management) Regulations require that for a project covered by those Regulations, a copy of this Certificate, together with schedules is included in the project health and safety documentation.
For safety reasons, the electrical installation will need to be inspected at appropriate intervals by a competent person. The maximum time interval recommended before the next inspection is stated on Page 1 under "Next Inspection".
This Certificate is intended to be issued only for a new electrical installation or for new work associated with an addition or alteration or to an existing installation. It should not have been issued for the inspection of an existing electrical installation. A "Periodic Inspection Report" should be issued for such an inspection.
The Certificate is only valid if a Schedule of Inspections and Schedule of Test Results are appended.

Why must we have earth electrodes
The principle of earthing is to consider the general mass of earth as a reference (zero) potential. Thus, everything connected directly to it will be at this zero potential, or above it by the amount of the volt drop in the connection system (for example, the volt drop in a protective conductor carrying fault current). The purpose of the earth electrode is to connect to the general mass of earth.
With the increasing use of underground supplies and of protective multiple earthing (PME) it is becoming more common for the consumer to be provided with an earth terminal rather than having to make contact with earth using an earth electrode.
The tester : The person who carries out the test and inspection must be competent to do so, and must be able to ensure his own safety, as well as that of others in the vicinity. It follows that he must be skilled and have experience of the type of installation to be inspected and tested so that there will be no accidents during the process to people, to livestock, or to property. The Regulations do not define the term 'competent', but it should be taken to mean a qualified electrician or electrical engineer.
Why do we need inspection and testing
There is little point in setting up Regulations to control the way in which electrical installations are designed and installed if it is not verified that they have been followed. the protection of installation users against the danger of fatal electric shock due to indirect contact is usually the low impedance of the earth-fault loop; unless this impedance is correctly measured. this safety cannot be confirmed. in this case the test cannot be carried out during installation, because part of the loop is made up of the supply system which is not connected until work is complete. In the event of an open circuit in a protective conductor, the whole of the earthed system could become live during the earth-fault loop test. The correct sequence of testing would prevent such a danger, but the tester must always be aware of the hazards applying to himself and to others due to his activities. Testing routines must take account of the dangers and be arranged to prevent them. Prominent notices should be displayed to indicate that no attempt should be made to use the installation whilst testing is in progress.
The precautions to be taken by the tester should include the following:
1. -make sure that all safety precautions are observed
2. - have a clear understanding of the installation, how it is designed and how it has been installed
3. - make sure that the instruments to be used for the tests are to the necessary standards ,
4. - check that the test leads to be used are in good order, with no cracked or broken insulation or connectors, and are fused where necessary to comply with the Health and Safety Executive Guidance Note GS38
5. - be aware of the dangers associated with the use of high voltages for insulation testing. For example, cables or capacitors connected in a circuit which has been insulation tested may have become charged to a high potential and may hold it for a significant time. ←←←

Essential Tests :
continuity of protective conductors : satisfactory ( GN-3 )

Insulation resistance:
Phase/neutral…………………………MΩ
Phase/earth …………………………MΩ
Neutral/earth …………………………MΩ
Earth fault loop impedance ………………………… Ω ( Live Test )

Polarity satisfactory

RCD operation (if applicable). Rated residual operating current I∆n ………mA and operating time of ………mS (at I∆n

Notes on the formal visual and combined inspection and test record ( Form VI.2 )

1, Register No - this is an individual number taken from the equipment register, for this particular item of equipment
2, Description of equipment, e.g. lawnmower, computer monitor
3, Construction Class - Class 0, 0I, I, II, III. Note that only Class I and II equipment may be used without special precautions being taken
4, Equipment types - portable, movable, hand-held, stationary, fixed, built-in
5/6 , Insert the location and any particular external influences such as heat, damp, corrosive, vibration.
Frequency of inspection - generally as suggested in Table 7.1 of the Code of Practice for In-Service Inspection and Testing of Electrical Equipment
Inspection - items 17-23 and 28 will be completed if an inspection is being carried out
Inspection and Test - the testing in items 24v and 26 should always be preceded by inspection.
9/11 ,The make, model and serial number of the item of equipment should be inserted ,
12/14 , The voltage for which the equipment is suitable, the current consumed and the fuse rating should be inserted ,
15/16 , The date of purchase and the guarantee should be completed by the client
17 , The date to be inserted is the date of the inspection or the date of the inspection and testing ,
18 , Environment and use. It should be confirmed that the equipment is suitable for use in the particular environment and is suitable for the use to which it is being put ,
19 , Authority is required from the user to disconnect equipment such as computers and telecom equipment - where unauthorised disconnection could result in loss of data , Authority should also be obtained if such equipment is to be subjected to the insulation resistance and electric strength tests.
20 , Socket-outlet/flex outlet. The socket or flex outlet should be inspected for damage including overheating.
If there are signs of overheating of the plug or socket-outlet, the socket-outlet connections should be checked as well as the plug. This work should only be carried out by an electrician
21/23 , The inspection required is described in Chapter 14 of the Code of Practice for In-Service Inspection and Testing of Electrical Equipment.
24 / 27 ,Tests. The tests are described in Chapter 15 of the Code of Practice for In-
Service Inspection and Testing of Electrical Equipment. The tests should always be preceded by the Inspection items 17-23 and 28. The instrument reading is to be recorded and a tick entered if the test results are satisfactory
28 , Functional Check - a check is made to ensure that the equipment works properly
29 , Comments/other tests. Additional tests may be needed to identify a failure more clearly or other tests may be carried out such as a touch current measurement. An additional sheet may be necessary, which should be referenced in the box on this record
30 , OK to use - ‘YES’ should be inserted if the item of equipment is satisfactory for use, ‘NO’ if it is not ,

 

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17th Edition Wiring Regulations Practice : Apprentice ,
Overall Percentage Score , 100%

Unit 1: Special installations or locations ( 100% )
Q1 : Zone O in a bathroom is the ( A ) Area within the bath or Shower , ( p-165 701.32.2 )
Hint !! Extreme end ,
Q2 : Zone 1 in a bathroom is the
Hint !! Not quite the extreme end , ( A ) Area directly above the bath or shower up to 2.25m above finished floor level . ( p-165 701.32.3 )
Unit 2 : Appendices ( 100% )
Q2 : BS-1362 relates to ( A ) Cartridge fuses for use in 13A plugs , ( p-229 BS – Standards )
Hint !! Used with BS- 1363
Unit 3 : Inspection & Testing ( 100% )
Q3 : An insulation Résistance test performed on a 50v a.c . SELV installation should be capable of producing a test voltage of
( A ) 250v dc ( p-158 / table 61 )
Hint !! think about ELV downlighters and the average voltage they use ,
Testing : Q 21 : An insulation résistance test performed on a 230v a.c installation should be capable of producing a test voltage ,
Hint !! what type powers the instrument ? ( A ) 500v DC ( p-158 / table 61 )
Unit 4 : Definitions ( 100% )
O4 : A double insulated hand held electric drilling machine is known as
Hint !! think about where you see the symbol , ( A ) Class II equipment ,
Q5 : BS-7671 IEE Regulations define Extra Low Voltage a.c as Not exceeding ( A ) 50 volts a.c , ( p-31 )
Unit 5 : Selection & erection of equipment ( 100% )
Q6 : where a wall consists of a metallic construction and it is necessary to install cables within that wall , the circuit should
( A ) be RCD protected ,
Unit 6 : protection for safety ( 100% )
Q7 : A device intended for safety reasons to cut off all or part of an installation from every source of electrical energy provides ,
( A ) Isolation ( 537 / 537.2 )
Q8 : what is the maximum Zs for a 32Amp type B circuit breaker protecting a standard ring final circuit ,
( A ) 144Ω ( p-49 / table 41.3 )
Unit 7 : Scope , Object and fundamental characteristics ( 100% )
Q9 : Inspection & Testing of an installation should be completed by ( A ) Competent person )
Hint !! Maybe someone who knows what they are doing :
Q10 ; BS-7671 is a ( A ) Non-Statutory document ,
Hint !! its Not enforceable in Law ,
Unit 8 : Assessment of general characteristics ( 100% )
Q 11 : Non-sheathed cables for fixed wiring , other than protective conductors , should be installed in , ( A ) Conduit or Trunking ,
Q 12 : who is responsible for specifying the first periodic inspection on an installation ?
Hint !! who knows everything about an installation before the Other ?
( A ) the person responsible for the design ,
Q 13 : Inspection & Testing of an installation should be completed by ?
Hint !! maybe someone who knows what they are doing ,
( A ) Competent persons ,
Q 14 : Basic protection protects against ?
Hint !! the most basic of contact ,
Electric shock under fault free conditions ,
Q 16 : Any overcurrent protective device installed at the origin of a circuit must have a breaking capacity of ?
Hint !! what cases the maximum current to flow under fault conditions ,
( A ) Equivalent or more to the prospective short circuit current ,
Q 17 : Non-sheathed cables for fixing wiring , other than protective conductors , should be installed in ,
Hint !! think what the sheathing provides on cable , ( A ) Conduit or Trunking ,
Q 18 : Undervoltage protection is required where the restoration of power may cause ,
Hint !! what can be dangerous if power is suddenly turned on ?
( A ) Unexpected starting of machinery ,
Q 19 : outdoor lighting involves all the following except ,
Hint !! Temporary installation , ( A ) Festoon lighting ,
Q 20 : where a wall consists of a metallic construction and it is necessary to install cables within that wall the circuit should ?
Hint !! needs additional protection , ( A ) be RCD protected ,

 

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PERIODIC INSPECTION REPORT FOR AN ELECTRICAL INSTALLATION
(REQUIREMENTS FOR ELECTRICAL INSTALLATIONS - BS 7671 [IEE WIRING REGULATIONS])
Extent and Limitations of the Inspection :
Extent of Electrical Installation covered by this report ,
Limitations ( see Regulation : 634.2 p-163 ,

Insulation resistance
If the DC resistance tests above fail to identify the cause of a circuit that is causing RCD tripping on its own (i.e. without the aid of the appliances usually connected to it). You may find that repeating the tests described using an insulation resistance tester will yield more information. Since the insulation resistance tester carries out the tests at much higher voltages than the multimeter (typically 500V) it will identify those few failures where the conduction path between a live conductor and earth is only visible at mains voltages.
Take care when performing these tests, it is possible to get a nasty shock off an insulation test meter!
Mitigating the effects of nuisance trips
While it is possible to eliminate most causes of nuisance trips with careful system design and testing, it is always wise to design the system to allow for the possibility of it happening:
* Provide dedicated non RCD protected circuits [see note] for vulnerable equipment such as:
*Freezers
* Central Heating Systems
* Heated Aquariums
* Fire or smoke alarms
* Security systems and lighting
* Computer and IT equipment
* Have as few circuits or devices as possible protected by the same RCD so that a trip impacts as few extraneous circuits as possible. The ultimate solution would use RCBOs for each circuit. Obviously expense has to be weighed against the implications of tripping.
* Use emergency lighting to backup any important lighting circuits that need to be RCD protected (i.e. on TT earthing systems). In particular these should include lighting for:
* Stairs
* Fire escape routes
* Near trip hazards or other difficult to navigate areas
* Near the consumer unit
* Consider using uninterruptible power supplies (UPS) to maintain running of critical equipment.
* Power failure alarms might also be an appropriate measure in some circumstances.
Note: With the advent of the 17th edition of the wiring regulations, one must comply with the requirement that any buried cables that don't have 30mA trip RCD protection, must still be adequately protected from physical damage. This can be achieved either via being buried at 50mm or greater depth in a wall, or with metallic earthed protection such as conduit or by using suitable metal sheathed cables like SWA, MICC etc. Note that new cable types are becoming available to help meet these requirements. Surface mounted cables may also be installed without additional RCD protection in some circumstances since it is assumed they are sufficiently visible to avoid accidental damage from drilling / nailing etc.
System design using RCDs
Some of the system design aspects of using RCDs to good effect are covered in the mitigation section above. However the following basic principles should also applied:
1. Use split load consumer units, to allow circuits that do not benefit from RCD protection to be powered directly.
2. Don't place too many circuits on the same RCD. In particular identify circuits that are likely to have high leakage (e.g. those containing lots of IT other electronic equipment).
3. Where RCDs need to be cascaded, use time delayed types for the upstream device so that trips are contained close to the cause of the fault.
4. Don't place circuits to outside electrics and outbuildings on the same RCD as protects the house circuits.
5. Avoid placing high leakage devices on RCD protected circuits where possible.
6. Design circuits such that the anticipated leakage is no more than 25% of the trip threshold. This will allow for later circuit extension.
7. Ensure accessories and wiring are not placed in excessively damp environments.
8. Don't use lower trip threshold devices that is appropriate for the level of risk present and protection sought.

NOTES ON COMPLETION OF MINOR ELECTRICAL INSTALLATION WORKSCERTIFICATE :

Scope :
The Minor Works Certificate is intended to be used for additions and alterations to an installation that do not
extend to the provision of a new circuit. Examples include the addition of socket-outlets or lighting points to
an existing circuit, the relocation of a light switch etc. This Certificate may also be used for the
replacement of equipment such as accessories or luminaires, but not for the replacement of
distribution boards or similar items. Appropriate inspection and testing, however, should always be
carried out irrespective of the extent of the work undertaken ,

Part 1 Description of minor works :
1,2 The minor works must be so described that the work that is the subject of the certification can be
readily identified.
4 : See Regulations 120.3 and 120.4. No departures are to be expected except in most unusual
circumstances. See also Regulation 633.1

Part 2 Installation details :
2 : The method of fault protection must be clearly identified e.g. earthed equipotential bonding and
automatic disconnection of supply using fuse/circuit-breaker/RCD
4 : If the existing installation lacks either an effective means of earthing or adequate main equipotential
bonding conductors, this must be clearly stated. See Regulation 633.2
Recorded departures from BS-7671 may constitute non-compliance with the Electricity Safety, quality
and continuity Regulations 2002 (as amended) or the Electricity at Work Regulations 1989. It is
important that the client is advised immediately in writing.

Part 3 Essential Tests :
The relevant provisions of Part 6 (Inspection and Testing) of BS 7671 must be applied in full to all minor
works. For example, where a socket-outlet is added to an existing circuit it is necessary to ;
1 : establish that the earthing contact of the socket-outlet is connected to the main earthing terminal
2 : measure the insulation resistance of the circuit that has been added to, and establish that it complies with Table 61 of BS 7671
3 : measure the earth fault loop impedance to establish that the maximum permitted disconnection time is not exceeded
4 : check that the polarity of the socket-outlet is correct
5 : (if the work is protected by an RCD) verify the effectiveness of the RCD

Part 4 Declaration :
1,3 The Certificate shall be made out and signed by a competent person in respect of the design , construction, inspection and testing of the work
1,3 The competent person will have a sound knowledge and experience relevant to the nature of the
work undertaken and to the technical standards set down in BS-7671 be fully versed in the inspection
and testing procedures contained in the Regulations and employ adequate testing equipment.
2 : When making out and signing a form on behalf of a company or other business entity, individuals shall state for whom they are acting ,

 

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SELV and PELV :

According to IEC 60364-4-41 protection against electric shock is deemed to be provided when:
• the nominal voltage cannot exceed an upper limit in accordance with IEC 60449 (50 V AC / 120 V DC)
• the supply is from a safety isolating transformer in accordance with IEC 60742 or equivalent (e.g. motor generator with windings providing an equivalent isolation)
• an electrochemical source (e.g. battery) or another source independent of a higher voltage circuit (e.g. diesel-driven generator),
• mobile sources or certain electronic devices all complying with appropriate standards, where measures have been taken in order to ensure that, even in the case of an internal fault, the voltage at the outgoing terminals cannot exceed the above mentioned levels , or
• when all above conditions are fulfilled and in addition electrical separation with either SELV for unearthed circuits or PELV for earthed circuits is provided
Arrangement of circuits :

IEC 60364-4-41 states that live parts of SELV and PELV circuits shall be electrically
separated from each other and from other circuits. Arrangements shall ensure electrical separation
not less than that between the input and output circuits of a safety isolating transformer ,
Circuit conductors of each SELV and PELV system shall preferably be physically
separated from those of any other circuit conductors. When this requirement is impracticable, one of the following arrangements is required
• Plugs and socket-outlets of SELV and PELV systems shall comply with the following requirements
– plugs shall not be able to enter socket-outlets of other voltage systems : – socket-outlets shall not admit plugs of other voltage systems :
– socket-outlets shall not have a protective conductor contact :

Requirements for unearthed circuits ( SELV ) :
According to IEC 60364-4-41, live parts of SELV circuits shall not be connected to
earth or to live parts or to protective conductors forming part of other circuits
Exposed conductive parts shall not be intentionally connected to :
* earth; or
* protective conductors or exposed conductive conductors of another circuit; or
* extraneous conductive parts.
If nominal voltage exceeds 25 V AC r.m.s or 60 V ripple-free DC, protection against direct contact shall be provided by:
* barriers or enclosures affording a degree of protection of at least IP2X or IPXXB; or
* insulation capable of withstanding a test voltage of 500 V AC r.m.s for 1 minute ,
In general, protection against direct contact is unnecessary if the nominal voltage
does not exceed 25 V AC r.m.s. or 60 V ripple-free DC. However, it may be necessary under certain
conditions of external influences, which is currently under consideration by the IEC.

 

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Why Earth ?
One side of the electricity supply (the neutral) is firmly connected to earth at the substation to prevent the supply 'floating' relative to earth for safety reasons.
Many electrically operated devices (e.g. washing machines, heaters and some lighting fittings) have exposed metalwork which could become live if a fault occurred. Anyone touching it could then receive a shock or even be killed depending on the current flowing through them to earth. To prevent this, an earthing conductor should be provided to all socket outlets, lighting circuits and any fixed appliances to which exposed metal parts are then connected. The earth connection limits the voltage which can appear on the exposed metal parts under fault conditions to a safe value until the fuse blows or the MCB or RCD trips. Note that earthing does not necessarily prevent anyone receiving a shock, but together with the time/current characteristics of the protective device (fuse, MCB or RCD) it should ensure that it is not lethal. It is desirable to make the impedance (resistance) of the earth wiring a low as practicable. (1000A flowing through 0.1 ohm drops 100V! )
Note that exposed metalwork cannot be protected by connection to the neutral because current flowing will cause a voltage drop between the metalwork and true earth. Also, if the neutral connection breaks or the appliance is plugged into a socket with line and neutral reversed (!), the metalwork will be at full mains voltage.
Appliances with an earth connection are called Class I (one): Class II or 'double insulated' appliances incorporate additional insulation to prevent exposed metalwork becoming live, and do not require an earth connection. This means that a 2-core mains lead can be used and internal earth connections are not needed.
A fundamental principle of electrical safety is that no single fault condition should cause a hazardous situation. This is why some of the regulations may appear to be rather stringent: it is better to be safe than sorry.
Who Supplies the Earth ?
The earth connection will usually be supplied by one of the following methods:
a). By the electricity company. Either through the armouring of the supply cable or through a combined neutral and earth conductor. The latter method is termed PME (protective multiple earthing) and requires some special attention (see below). There will usually be a label near the meter indicating a PME system.
b). Through an earth electrode; usually a rod or plate driven into the ground. This method is found where the electricity company cannot easily supply or guarantee an adequate earth conductor; for example, where the supply comes on a pair of overhead wires. The user is generally responsible for the adequacy of the earth electrode.
The method of earthing can normally be found out by tracing the wiring from the meter/consumer unit. It is usually fairly obvious. IMPORTANT! - It is no longer permitted to use a water or gas pipe for the main or only earthing connection. There may, however be earth bonding wires connected onto the water and gas pipes for 'equipotential bonding' (see below). If there is no electricity company earth or dedicated separate earth electrode, then one must be provided. Contact the electricity company if in any doubt.

Earthing of Electrical Installation :
Each circuit requires an earth conductor to accompany (but kept separate from) the line and neutral conductors throughout the distribution. Where the distribution is in the form of a ring, the earth connection must also complete the ring.
The bare tails of earth conductors must be insulated with green/yellow sleeving from the exit from the cable sheath to the earth terminal.
All metal boxes should be connected to the earth; either through a short tail covered with green/yellow sleeving to the socket earth terminal or directly by the earth conductor for a switch box.
Equipotential Bonding
As mentioned elsewhere, a fault current flowing in the earth wiring will cause the voltage on that wiring to rise relative to true earth potential. This could cause a shock to someone touching, for instance, the case of a faulty washing machine and a water tap at the same time. In order to minimise this risk, an 'equipotential zone' is created by connecting the services to the main earthing point. Such services are:
• Water Pipes
• Gas Pipes
• Oil Pipes
• Central Heating
• Metallic Ventilation Trunking
• Exposed Parts of Building Structure
• Lightning Conductor
• Any other Metallic Service

WHY DO LIGHT BULBS ALWAYS BLOW WHEN YOU SWITCH THEM ON, AND WHY DO THEY BLOW FUSES ?
An ordinary incandescent "light bulb" consists of a thin tungsten filament in a glass envelope containing an inert gas. The filament has a relatively high resistance, and thus gets hot - hot enough to give out useful amounts of light as well as lots of heat - when current is flowing through it. The inert gas prevents the hot tungsten rapidly oxidising, as it would in air, or rapidly evaporating, as it would in a vacuum. It does, however, reduce efficiency, by conducting heat away from the filament. (Different gases and pressures are selected for different applications: for example, krypton and xenon are advantageous because they convect less and prevent evaporation better than argon/nitrogen, and therefore allow a hotter, more efficient, filament to be used while maintaining lamp life. Note that quartz halogen bulbs are different again: here, evaporated tungsten is re-deposited on the filament, thus allowing it to be hotter still while maintaining its life.)
Tungsten, being a metal, has a resistivity which increases as its temperature rises. Therefore, when you switch on a lamp, it presents a much lower resistance than normal to the passage of electricity, and so your beefy electricity supply will drive through a great deal more current than normal while the filament heats up, putting it under thermal stress as it expands. This on its own encourages the filament to give up and break, but it is exacerbated by the fact that any thinned section will incur extra stress, as it will heat up more quickly than the rest of the filament (being thinner), present a higher resistance, and thus dissipate even more than its fair share of the (increased) power. This will tend to thin it further, rapidly, and hence lead to a point of failure.
How do you deal with it? Well, using a rotary on/off dimmer, where you always have to switch on the lamp at its lowest brightness, will help a lot. A dimmer will reduce the maximum available light output slightly. You can also fit negative temperature coefficient thermistors in series with the bulb. These have a resistance/temperature characteristic with the opposite slope to that of the filament, so give a "soft start" until they themselves warm up. Again, you will lose a little brightness, and waste a little energy in the hot thermistors. I am not aware of any "off the shelf" products containing thermistors, probably because they need to be selected for the wattage of lamp required.
It should be noted, however, that it is probably counterproductive to try to keep a light bulb alive for too long. This is because the thinned filament will be taking less current, so the light output will be reduced, and the tungsten that has evaporated from it will be deposited on the inside of the glass, reducing efficiency by blocking some of the light.
As regards blowing the fuse, this is never directly due to a broken filament falling onto the lead-out wires, and thus presenting a much lower resistance, but is due to the gas or vaporised filament in the bulb becoming ionised. The high temperature and large electric field (full mains voltage across a very small gap) which occurs when the filament breaks can cause the gas to go into a conducting state, and the plasma will "spread" until it shorts out the lead-out wires, because it presents a much lower resistance than the filament. This causes a "pop" due to rapid heating, and has been known to cause the envelope to explode. Light bulbs usually have built-in fuses to deal with this, but as they are built down to a price, they aren't always effective.
If you plug in a new light bulb and it only lasts a few seconds, leaving a white pattern on the glass, this is because it has cracked at some point, letting air in. When energised, the filament has oxidised to white tungsten oxide, which condenses on the glass in a pattern corresponding to the flow of air inside as the lamp is switched on.
Oh, by the way, "extra-long life" bulbs seem to be a con. They just run at a lower temperature than normal bulbs, thus lasting longer, but being a lot less efficient. There is no justification for the extortionate prices charged for them.

 

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Cables in contact with polystyrene

Do not let electrical cables come into contact with polystyrene. It slowly leaches the plasticiser out of the PVC, so that it becomes stiff and brittle. Sometimes it looks like the PVC has melted and run a little.

* Shaver sockets incorporate special isolating transformers which provide an earth-free output. The primary (input) side requires an earth which is connected internally to the transformer core.

Protective Multiple Earthing (PME.)
With PME. the neutral and earth conductors of the supply are combined. The supply company connects the neutral solidly to earth frequently throughout the distribution network. At the customer's connection point the company supplies an 'earth' (which is actually connected to the neutral) to which all the installation earths and equipotential bonding are connected. Note that within the installation, the earth and equipotential bonding are kept separate from the neutral in the usual way.
With PME. there is a potential danger in that if the combined neutral/earth conductor of the supply became broken (very unlikely but nevertheless possible), the voltage on the earth conductors could rise towards the full supply voltage. It is most important therefore that equipotential bonding is rigorously applied in installations supplied by PME. The minimum size of main bonding conductor is 10 sq mm but may need to be up to 25 sq mm depending on the size of the incoming neutral/earth conductor: the supply company will advise you.
Electricity System Earthing Arrangements
Mains electricity systems are categorised in the UK according to how the earthing is implemented. The common ones are TN-S, TN-C-S and TT. You will sometimes see these referred to in questions and answers about mains wiring.
Note that in these descriptions, 'system' includes both the supply and the installation, and 'live parts' includes the neutral conductor.
First letter:
T The live parts in the system have one or more direct connections to earth.
I The live parts in the system have no connection to earth, or are connected only through a high impedance.
Second letter:
T All exposed conductive parts are connected via your earth conductors to a local ground connection.
N All exposed conductive parts are connected via your earth conductors to the earth provided by the supplier.
Remaining letter(s):
C Combined neutral and protective earth functions (same conductor).
S Separate neutral and protective earth functions (separate conductors).
TN-C No separate earth conductors anywhere - neutral used as earth throughout supply and installation
TN-S Probably most common, with supplier providing a separate earth conductor back to the substation.
TN-C-S [Protective Multiple Earthing] Supply combines neutral and earth, but they are separated out in the installation.
TT No earth provided by supplier; installation requires own earth rod (common with overhead supply lines).
IT Supply is e.g. portable generator with no earth connection, installation supplies own earth rod.
Inside or nearby your consumer unit (fuse box) will be your main earthing terminal where all the earth conductors from your final sub-circuits and service bonding are joined. This is then connected via the 'earthing conductor' to a real earth somehow...
TN-S The earthing conductor is connected to separate earth provided by the electricity supplier. This is most commonly done by having an earthing clamp connected to the sheath of the supply cable.
TN-C-S The earthing conductor is connected to the supplier's neutral. This shows up as the earthing conductor going onto the connection block with the neutral conductor of the supplier's meter tails. Often you will see a label warning about "Protective Multiple Earthing Installation - Do Not Interfere with Earth Connections" but this is not always present.
TT The earthing conductor goes to (one or more) earth rods, one of them possibly via an old Voltage Operated ELCB (which are no longer used on new supplies).
There are probably other arrangements for these systems too. Also, a system may have been converted, e.g. an old TT system might have been converted to TN-S or TN-C-S but the old earth rod was not disconnected.

 

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Consumer Units
Live parts must be contained inside enclosures or behind barriers providing a degree of protection of at least IX2X or IPXXB. 416.2.1
The horizontal top surface of a readily Accessible barrier or enclosure must provide a degree of protection of at least IX4X or IPXXD. 416.2.2
All installations must be divided into separate circuits so as to comply with the following :
- avoid danger and inconvenience if a fault develops
- allow safe maintenance, inspection & testing
- prevent any danger that may be caused by the loss of supply to a single circuit e.g. a lighting circuit
- reduce the possibility of nuisance tripping of RCDs by equipment with high cpc currents produced in normal use e.g. computers
- prevent electromagnetic interference between items of electrical equipment
- prevent the accidental energising of an isolated circuit .
314.1

A double pole main switch or linked circuit breaker must be installed as close as possible to the incoming supply at the origin of the installation. 537.1.4
Unless specifically labelled or suitably identified, all 13A socket outlets must be 30ma RCD protected. 411.3.3
Fire detection circuits must be supplied independently of other circuits and not protected by an RCD protecting multiple circuits. 560.7.1
Fire detection .cables, not including metal screened fire resistant cables, must be adequately segregated from cables supplying other circuits. 560.7.7
Extra Low Voltage circuits should not be run in the same wiring system as 230v circuits unless all ELV cables and conductors are insulated for 230v or separated by an earthed metal screen. 528.1
All electrical equipment must be accessible for operation, inspection & testing , maintenance and repair. 132.12
Before an installation or an addition / alteration to an installation is energised, inspection and testing must be carried out to ensure the requirements of BS-7671 have been met and an appropriate Certificate must then be issued. 134.2.1, 610.6, 631.1
Any defects found in the existing installation must be recorded on the Electrical Installation Certificate or Minor Electrical Installation Works Certificate. 633.2
A single pole fuse or circuit breaker must be used with the line conductor only. 132.14.1
Only a linked circuit breaker that breaks all related line conductors can be used with an earthed natural conductor. 132.14.2
All final circuits must be connected to a separate way in the consumer unit. 314.4
In a ccu the natural conductors and cpc's should be connected to their respective terminals in the same order as the phase conductors are connected to the mcb's. 514.1.2

An unfused spur may be connected to the origin of a radial or ring final circuit in the consumer unit. 433.1
All protective devices must be labelled. 514.8.1
A periodic inspection notice must be fixed on or next to the ccu. 514.12.1
Where applicable an RCD notice must be fixed on or next to the ccu. 514.12.2
Where the installation contains wiring colours to two versions of BS-7671 a warning notice must be fixed on or next to the ccu. 514.14.1
A voltage warning notice is only required where a nominal voltage exceeding 230v exists. 514.10.1
A durable copy of the schedule from the electrical installation certificate must be fixed next to or placed inside the consumer unit. In addition to circuit details the schedule must also contain information about the protective measures used in the installation ie automatic disconnection of supply, electrical separation , SELV , RCD. 132.13, 514.9
All literature supplied with fire detection equipment must be made available to the occupant of the dwelling. 560.7.12
Fuses and mcb's must have a breaking capacity greater than or equal to the maximum PFC at the point where the device is installed. 432.1 A lower breaking capacity is allowed if another fuse or mcb with the necessary breaking capacity is installed on the supply side and the energy let-through of both devices will not damage the fuse or mcb on the load side. 434.5.1, 536.1
Consumer units must be spaced at least 150mm away from gas pipes unless there is a pane of non combustible insulating material separating them. OSG p18
In areas subject to flooding, consumer units should preferably be installed above flood water level. OSG p161
Overcurrent protection devices must comply with one or more of the following standards :

Bs 88-2.2 .
Bs 88-6 .
Bs 646 .
Bs 1361 .
Bs 1362 .
Bs 3036 .
Bs en 60898-1 & -2 .
Bs en 60947-2 & -3 .
Bs en 60947-4-1, -6-1 & -6-2 .
Bs en 61009-1 .
533.1

MINOR ELECTRICAL INSTALLATION WORKS CERTIFICATE : p-335 / 336

GUIDANCEFOR RECIPIENTS (to be appended to the Certificate)
This Certificate has been issued to confirm that the electrical installation work to which it relates has been
designed, constructed and inspected and tested in accordance with British Standard 7671, (the IEE Wiring
Regulations). You should have received in ‘original’ Certificate and the contractor should have retained
duplicate. If you were the person ordering the work, but not the owner of the installation, you should
pass this Certificate, or copy of it, to the owner.
A separate Certificate should have been received for each existing circuit on which minor works have been
carried out. This Certificate is not appropriate if you requested the contractor to undertake more extensive
installation work., for which you should have received an Electrical installation Certificate.
The Certificate should be retained in safe place and be shown to any person inspecting or undertaking
further work on the electrical installation in the future. If you later vacate the property, this Certificate
will demonstrate to the new owner that the minor electrical installation work carried out complied with
the requirements of British Standard 7671 at the time the Certificate was issued.

MINOR ELECTRICAL INSTALLATION WORKS CERTIFICATE :
(REQUIREMENTS FOR ELECTRICAL INSTALLATIONS - BS 767 ( IEE WIRING REGULATIONS )
To be used only for minor electrical work which does not include the provision of new circuit

Agreed limitations on the inspection and testing ← with Client ,

Declaration
I/We certify that the electrical installation work, as detailed in part 1 of this certificate, do not impair the safety of the existing installation, that the said works have been
designed, constructed, inspected and tested in +accordance with BS 7671:2008 * ( IEE Wiring Regulations), amended to the date shown* and that to the best of my/our
knowledge and belief, the time of my/our inspection, complied with BS 7671 except as detailed in Part 1 of this certificate.
This form is based on the model shown in Appendix 6 of BS 7671: 2008

239- Inspection Testing & Certification of Electrical Installations Exam : Part B scenario :
Solution to terminating the underground SWA supply cable :
-&-'s question may lead you to terminate the SWA of the underground supply cable, since the question informs you. "You are NOT allowed to use the supply companies earthing system as a means of earthing the outhouse" However -&-'s mention nothing about earthing the supply cable itself. It is difficult to decide whether -&-'s are just testing the candidates knowledge of this situation VERY thoroughly or alternatively offering a red-herring to mislead the unwary candidate. Whichever is the reason for this question, it caused many exam candidates a great deal of difficulty and lost time trying to decide what the solution was.

The actual solution stems from BS 7671 regulation 542.1.8 part of this reg states , ←

"If the protective conductor ( i.e. the swa ) forms part of a cable, the protective conductor shall be earthed only in the installation containing the associated protective device" This therefore has to be the main house end. See the only possible solution below :
( Main house CCU / TN-C-S / Systems ) MET : ←←

part B scenario : gave many candidates a difficult time. Here you were presented with a TN-C-S system installed in a domestic property, and an underground supply cable is being used to supply an external outhouse. However the electricity supply company will not allow you to use their means of earthing for the outhouse. So how do you provide a means of earthing for the outhouse? Where do you earth the supply cable? What checks must you make on the underground supply cable? Why can't you use the main house TN-C-S system as a means of earthing the outhouse ?

 

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Many candidates continue to get the value of Zs wrong for the circuit in question in part B of the exam.
A common error when completing questions involving schedule of test results is to forget to indicate functional tests have been performed and found satisfactory/unsatisfactory. To tick the tick box when completing details of ring final circuits, ensuring to indicate continuity of ring final conductors have been performed.
Failure to record the type of earthing system, i.e. TN-S, TN-C-S, TT,
Failure to record the value of Ze, PFC, Nominal voltage, Nominal frequency, are common errors.
Test procedures
A very common question is to explain in detail how to perform an insulation resistance test, often on a lighting circuit. Candidates regularly fail to state the instrument used which is an 'Insulation Resistance Ohm-meter' (Not a Megger! You will not gain any marks if you answer a Megger) Many candidates fail to identify the test voltage required for typical 230/240 volt installation which is 500 volts and the acceptable test value which is 0.5 Meg-ohm or greater (again due to change under 17th edition to a minimum acceptable value of 1.0 Meg-ohm) City and Guilds usually deliberately pick a lighting circuit that is stipulated as having two way switching, just to see if the candidate mentions to test the strappers in BOTH positions.
Failure to mention testing the insulation resistance of both strappers will lose you marks. Be warned!
Candidates regularly make mistakes when answering RCD questions. Often the question or specifications usually given in part B will make reference to a specific type of RCD for example a 30 mA RCD. Candidates are then asked to state the actual test current applicable to test this type of RCD. Candidates regularly incorrectly state the answer as x1/2 x1 and x5 instead of x1/2 = 15mA x1 = 30mA and x5 = 150mA

'Memorandum of Guidance on the Electricity at Work Regulations 1989'
This may help you somewhere on your 2391 ,

5. General :

1. The majority of the regulations are directed at hardware requirements. Installations are required to be of proper construction; conductors must be insulated or other precautions taken; there must be means of cutting off the power and means for electrical isolation. The hardware requirements are complemented by a group of regulations stating principles of safe working practice. Regulation 14, which covers live working, is of particular importance.
2. The scope of the EAW Regulations is limited by the definition of danger and injury solely to risks arising from an electrical source and does not include, for example, control-system faults and consequent hazards such as aberrant machinery behavior.
3. The EAW Regulations revoke a number of specific regulations, but a number remain which either overlap or appear to overlap, for example
1. the Electricity Safety, Quality and Continuity Regulations 2002 (as amended): see the introduction to the Memorandum of guidance.
2. the Low Voltage Electrical Equipment (Safety) Regulations 1988 (made under the Consumer Protection Act 1987);
3. the Building (Scotland) Regulations 2004: these give deemed to satisfy status to BS7671 Requirement for Electrical Installations (also known as the Institution of Electrical Engineers Wiring Regulations, 16 th Edition); and
4. the Cinematographic (Safety) Regulations, 1955.
If demarcation between these sets of regulations and the EAW Regulations is unclear in a particular case, then details should be passed to HSE, via the Enforcement Liaison Officer.
4. Appendices 1 and 2 of the Memorandum of guidance list publications relating to electrical safety.

6. Enforcement
1. There is no expectation that inspectors should change their general approach to enforcement. However, particular attention should be paid to the enforcement of reg 14. (Work on, or near, live conductors).
2. In situations where the 1908 Regulations previously applied or where HSW Act was used, inspectors should now enforce the EAW Regulations.
3. There should be no difference in enforcement between situations in which no specific regulations previously applied and those which were regulated
4. Nothing is required by the EAW Regulations which is not already the norm in the best undertakings.
5. The EAW Regulations will apply to electrical work in domestic premises. Such work will fall to HSE to enforce.
6. Expert assistance to prove the presence of electricity should not be necessary when contemplating enforcement action. Circumstantial evidence should suffice to indicate that electricity is present and that the EAW Regulations apply. Such evidence could include:
1. that the equipment carried a plate indicating that it worked at mains voltage;
2. that the equipment was connected to a supply via a 3-pin plug;
3. that the premises were supplied with electricity for lighting which was working; and
4. that a person on the premises paid an electricity bill.
In court, an expert witness should be able to use such evidence to express a professional opinion as to the dangers which were present or likely to occur.
7. It may also be possible to use an on-site electrician to measure voltages and use his or her measurements in evidence.
8. An improvement notice may be appropriate it conductors are inadequately protected against damage; for example, not routed through conduit, tubing or armouring in premises where the risk of physical damage is apparent. In particularly arduous conditions, e.g. construction work, stronger action may be considered.
9. Exposed and accessible live conductors or a lack of earthing could justify a prohibition notice. Lack of earthing can only be proved by measurement; simple observation is never adequate.

7. Interpretation (Reg 2)
1. The definitions of danger and injury are linked but distinguished to accommodate those circumstances when persons must work on or so near live equipment that there is a risk of injury, ie where danger is present and cannot be prevented.
2. Danger includes danger to the public.
3. The definition of electrical equipment excludes items which only generate electricity adventitiously, eg as static.
4. Earthing and isolation are defined in regs.8 and 12 respectively.
8. Duties (Reg 3)
1. Regulation 3 imposes duties only on employers, employees, the self-employed, and mine or quarry managers. In other cases HSW Act ss.3 and 4 will apply.
2. All duties are limited by the phrase "to matters which are within his control", apart from reg.3(2)(a) which is similar to HSW Act, s.7(b). Some large industries tend to produce written rules which clearly define the extent of an individual's control but it will often be the case that there is overlapping liability where several individuals and/or bodies corporate are duty holders.

9. Systems, work activities and protective equipment (Reg 4)
1. Regulation 4 acts as a catch-all requirement.
2. Due to the broad definition of system (reg 2), reg 4 covers almost every conceivable electrical danger: from an exploding lithium battery in a calculator to the output side of a power station.
3. Systems in vehicles are covered by reg 4, but note should be taken of reg 32 in relation to ships, aircraft and hovercraft.
4. Regulation 4(3) embraces all work which could lead to electrical danger, although such work may not be associated with an electrical system. This would include work in the vicinity of electrical equipment and insulated or uninsulated conductors. The requirement does not limit proximity to conductors, live or dead, but rather regulates the work activity so as not to give rise to danger.
5. Regulation 4(3) is almost always applicable to work on or near underground cables, in which situations the standards of the Construction (GP) Regulations, reg 44 should be maintained, viz electrical isolation by disconnection and secure separation from sources of electrical supply. However, reg 14 should be used if there has been a failure to switch off the supply to such cables before undertaking work. That said, the circumstances of each case will dictate which regulation should be used.
6. The duties in reg 4(4) are not qualified by "so far as is reasonably practicable' and link with reg 14(c) ensuring that protective equipment provided is always suitable for the purpose.
10. Strength and capability of electrical equipment (Reg 5)
1. The assigned rating of electrical equipment represents the extent to which it may be used in an assessment of the adequacy of equipment strength and capability in foreseeable conditions of actual use; but may not necessarily represent all factors to be considered. A technical judgement by a competent person will often be needed to determine adequacy.
2. If a failure has occurred it may be relatively easy to prove a contravention. However, expert support will be required except where a deficiency is obvious and requires no technical proof.

 

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11. Adverse or hazardous environments (Reg 6)
1. Regulation 6 addresses extrinsic effects which are reasonably foreseeable. For example, in order to prove a contravention of reg.6, it is not necessary to show that electrical equipment is or has been exposed to a flammable atmosphere, but only that it is foreseeable that it could be so exposed.
2. The Memorandum of guidance gives general advice on the different hazardous environments covered by reg 6, and makes reference to relevant standards and publications.
12. Insulation, protection and placing of conductors (Reg 8)
1. This regulation is an example of where the EAW Regulations extend protection to anyone exposed to electrical danger from electrical equipment, including those not at work
13. Earthing and other suitable precautions (Reg 8)
1. This regulation applies to any conductor and not just to metal. It also allows other suitable means of preventing danger as an alternative to earthing.
2. The duty to prevent danger arising is activated only when a relevant conductor becomes charged.
3. Regulation 4 requires that systems are constructed so as to prevent danger; but in the event that danger arises because a conductor which should be earthed is not, reg.8 also becomes relevant.
4. As regards adequate earthing, the use of a conductor with a small cross-sectional area, which is not capable of carrying a heavy current for the duration of the fault, is not acceptable.
5. Inspectors should continue to press for the use of reduced voltage lighting and power tools, e.g. 110v centre tapped to earth in the working environments described in para 19 of the Memorandum of Guidance (e.g. construction work).

14. Integrity of reference conductors (Reg 9)
1. Regulation 9 is fully explained in the Memorandum of guidance.
15. Connections (Reg 10)
1. The definition of danger means that connections have to be mechanically and electrically suitable to prevent the risk of electrical injury.
16. Means for protecting from excess current (Reg 11)
1. The due-diligence defence in reg 29 is important when enforcing this requirement because, in theory, it is impossible in an absolute sense to prevent danger arising before any excess current protection device operates.
17. Means of cutting off the supply and for isolation (Reg 12)
1. This regulation cannot be used to require means to prevent non-electrical hazards arising from the use of electrical controlled systems.
2. Permit-to-work systems relying on a warning notice may be encountered. Where such systems are well established, tried and tested they could represent adequate isolation. However, they need to meet the minimum requirements of this regulation and when assessing such systems, inspectors should seek expert assistance, where appropriate.
3. Regulation 12 covers electrical equipment which may become charged by means other than connection to the supply, e.g. through capacitance or induced current arising from proximity to other live conductors.
4. There are no voltage limits.
18. Precautions for work on equipment made dead (Reg 13)
1. Regulation 13 may apply during any work, be it electrical or non-electrical.

19. Work on or near live conductors (Reg 14)
1. This regulation is very important and should be used to reduce the incidence of live working and to ensure strict precautions are adhered to when such work is carried out.
2. All 3 conditions stipulated in the regulation must be met before live working is permitted.
3. "Reasonable in all the circumstances" (reg 14(b)) means that all necessary precautions must be taken to ensure it is reasonable for someone to be asked to work.
4. Regulation 14(c) could imply that in the absence of injury no precautions can be required in advance. This would mean that notices requiring such precautions could not be issued. This interpretation is not correct because:
1. it would not be reasonable to work in a situation where the necessary precautions had not been taken; and
2. in order to take precautions it is necessary to foresee the potential harm, and such precautions will only be suitable if they are adequate to prevent the harm foreseen.
Therefore, if an inspector judges that the precautions taken will not prevent injury, he or she could issue a notice citing an apparent breach of reg 14.
5. Inspectors should question all live working wherever they find it. This could be in many establishments and also where peripatetic electricians are working.
6. The issue of accompaniment during live work is touched upon in the Memorandum of guidance. The presence of a colleague who could render assistance if safe to do so could prevent injury or mitigate its extent.
20. Working space, access and lighting (Reg 15)
1. This regulation only applies to the period during which work is being carried out.
2. It can be used to prevent the storage of goods etc in front of switchboards on the basis that the act of operating switching device is considered to constitute work on the equipment in question.

21. Competence to prevent danger and injury (Reg 16)
1. If competence is in doubt, inspectors should enquire into:
1. technical knowledge, and
2. experience
in relation to the work activity being undertaken. Clearly, more knowledge is required of those involved in high voltage work compared to those doing 25-volt test work.
2. HSE specialist support is available for assessing electrical competence (via the ELO).
3. The regulation does not require authorisation of competent persons but in conjunction with regs 4 and 14 such authorisation may be required, when necessary, to avoid danger.
4. The regulation does not specify any age limitations. The key requirements are adequate and relevant knowledge and experience, or an appropriate degree of supervision to allow persons to work safely and possibly to acquire those attributes.
22. Defence (Reg 29)
1. The defence only becomes relevant once it has been established that an offence has been committed. It should not affect the judgement of the duty holder as to the steps he or she should take to meet an absolute requirement
2. Employers may suggest that they have taken reasonable steps to meet their obligations by the delegation of responsibility to adequately qualified and instructed staff. This approach is pre-empted by the specific duties placed upon employers and others by reg 3.
3. HSE electrical specialists may be able to provide technical support in relation to a due diligence defence.

23. Exemptions (Reg 30)
1. Any applications for an exemption should be forwarded, together with a full report, to the Local Authority Unit.
24. Disapplication of duties (Reg 32)
1. The EAW Regulations apply to all vehicles, except those exempted by this regulation
2. Sea-going ships are exempt in relation to normal shipboard activities under the direction of the Master, whether they are in dock or under way in an inland waterway or at sea.
3. The term sea-going is not defined in these or any other health and safety regulations, but the intended meaning is clear and common to other regulations (eg Docks, COSHH).
4. The reference to any person in reg 32(b) includes the employer.

Appendix
Key issues on which the EAW Regulations And Electricity (Factories Act) Special Regulations 1908 And 1944 (Plus Exemptions) differ
1. Appendix 3 of the Memorandum of guidance gives information on reg 17 of the old regulations in relation to the new provisions. The minimum dimensions for switchboard passage-ways are given tacit approval.
2. Regulation 14 of the EAW Regulations covers all live working not just work on switchboards above 650 volts.
3. There is no specific requirement under the EAW Regulations for the display-of an electric shock placard or an abstract of the 1908/1944 Regulations. Occupiers should be told to remove abstracts but advised to retain placards where these are appropriate (see page 32, para 23 of Memorandum). There is no objection to occupiers displaying the new regulations in placard form if they desire.
4. There are no voltage bandings in the EAW Regulations.
5. There are differences in definitions between old and new. In particular conductor and danger have different meanings in the EAW Regulations.
6. Regulation 5 of the EAW Regulations corresponds to reg 1 of 1908 but is confined to the prevention of electrical danger. It does not cover machine malfunctions from electrical faults. All at risk are covered by reg 5, not just employees.
7. Under reg 6 of the EAW Regulations (as opposed to reg 27 of 1908) it is no longer necessary to show that equipment is or has been exposed to a flammable atmosphere. A foreseeable exposure will suffice.
8. Regulation 8 of the EAW Regulations applies to all conductors, unlike reg 21 of 1908 which only applied to exposed metalwork.
9. Regulation 13 of 1908 required the earthing of mobile generators. Under the EAW Regulations, reg 8 permits alternative approaches where earthing is not practicable.
10. The EAW Regulations contain no specific requirement for the written authorisation of competent persons, although authorisation may be required when necessary to avoid danger.

 

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Electrical Safety and you : ( HSE )
INTRODUCTION :
Electricity can kill. Each year about 1000 accidents at work involving electric shock
or burns are reported to the Health and Safety Executive (HSE). Around 30 of
these are fatal. Most of these fatalities arise from contact with overhead or
underground power cables.
Even non-fatal shocks can cause severe and permanent injury. Shocks from faulty
equipment may lead to falls from ladders, scaffolds or other work platforms.
Those using electricity may not be the only ones at risk: poor electrical
installations and faulty electrical appliances can lead to fires which may also cause
death or injury to others. Most of these accidents can be avoided by careful
planning and straightforward precautions.
This leaflet outlines basic measures to help you control the risks from your use of
electricity at work. More detailed guidance for particular industries or subjects is
listed on pages 6 - 8. If in doubt about safety matters or your legal responsibilities,
contact your local inspector of health and safety. The telephone number of your
local HSE office will be in the phone book under Health and Safety Executive. For
premises inspected by local authorities the contact point is likely to be the
environmental health department at your local council.
WHAT ARE THE HAZARDS ?
The main hazards are:
■ contact with live parts causing shock and burns (normal mains voltage,
230 volts AC, can kill);
■ faults which could cause fires;
■ fire or explosion where electricity could be the source of ignition in a
potentially flammable or explosive atmosphere, e.g. in a spray paint booth.
ASSESSING THE RISK :
Hazard means anything which can cause harm. Risk is the chance, great or small, that someone will actually be harmed by the hazard.
The first stage in controlling risk is to carry out a risk assessment in order to
identify what needs to be done. (This is a legal requirement for all risks at work.)
When carrying out a risk assessment:
■ identify the hazards;
■ decide who might be harmed, and how;
■ evaluate the risks arising from the hazards and decide whether existing
precautions are adequate or more should be taken;
■ if you have five or more employees, record any significant findings;
■ review your assessment from time to time and revise it if necessary.
The risk of injury from electricity is strongly linked to where and how it is used.
The risks are greatest in harsh conditions, for example:
■ in wet surroundings - unsuitable equipment can easily become live and
can make its surroundings live;
■ out of doors - equipment may not only become wet but may be at
greater risk of damage;
■ in cramped spaces with a lot of earthed metalwork, such as inside a tank
or bin - if an electrical fault developed it could be very difficult to avoid
a shock.
Some items of equipment can also involve greater risk than others. Extension
leads are particularly liable to damage - to their plugs and sockets, to their
electrical connections, and to the cable itself. Other flexible leads, particularly
those connected to equipment which is moved a great deal, can suffer from
similar problems.

REDUCING THE RISK
Once you have completed the risk assessment, you can use your findings to
reduce unacceptable risks from the electrical equipment in your place of work.
There are many things you can do to achieve this; here are some.
Ensure that the electrical installation is safe
■ install new electrical systems to a suitable standard, e.g. BS 7671 Requirements
for electrical installations, and then maintain them in a safe condition;
■ existing installations should also be properly maintained;
■ provide enough socket-outlets - overloading socket-outlets by using
adaptors can cause fires.
Provide safe and suitable equipment
■ choose equipment that is suitable for its working environment;
■ electrical risks can sometimes be eliminated by using air, hydraulic or hand powered
tools. These are especially useful in harsh conditions;
■ ensure that equipment is safe when supplied and then maintain it in a safe
condition;
■ provide an accessible and clearly identified switch near each fixed machine
to cut off power in an emergency;
■ for portable equipment, use socket-outlets which are close by so that
equipment can be easily disconnected in an emergency;
■ the ends of flexible cables should always have the outer sheath of the cable
firmly clamped to stop the wires (particularly the earth) pulling out of the
terminals;
■ replace damaged sections of cable completely;
■ use proper connectors or cable couplers to join lengths of cable. Do not
use strip connector blocks covered in insulating tape;
■ some types of equipment are double insulated. These are often marked with
a ‘double-square’ symbol . The supply leads have only two wires - live
(brown) and neutral (blue). Make sure they are properly connected if the
plug is not a moulded-on type;
■ protect light bulbs and other equipment which could easily be damaged in
use. There is a risk of electric shock if they are broken;
■ electrical equipment used in flammable/explosive atmospheres should be
designed to stop it from causing ignition. You may need specialist advice.
Reduce the voltage
One of the best ways of reducing the risk of injury when using electrical equipment
is to limit the supply voltage to the lowest needed to get the job done, such as:
■ temporary lighting can be run at lower voltages, eg 12, 25, 50 or 110 volts;
■ where electrically powered tools are used, battery operated are safest;
■ portable tools are readily available which are designed to be run from a
110 volts centre-tapped-to-earth supply.
Provide a safety device
If equipment operating at 230 volts or higher is used, an RCD (residual current
device) can provide additional safety. An RCD is a device which detects some, but
not all, faults in the electrical system and rapidly switches off the supply. The best
place for an RCD is built into the main switchboard or the socket-outlet, as this
means that the supply cables are permanently protected. If this is not possible a
plug incorporating an RCD, or a plug-in RCD adaptor, can also provide additional safety.

RCDs for protecting people have a rated tripping current (sensitivity) of not more
than 30 milliamps (mA). Remember:
■ an RCD is a valuable safety device, never bypass it;
■ if the RCD trips, it is a sign there is a fault. Check the system before using it
again;
■ if the RCD trips frequently and no fault can be found in the system, consult
the manufacturer of the RCD;
■ the RCD has a test button to check that its mechanism is free and
functioning. Use this regularly.
Carry out preventative maintenance
All electrical equipment and installations should be maintained to prevent danger.
It is strongly recommended that this includes an appropriate system of visual
inspection and, where necessary, testing. By concentrating on a simple, inexpensive
system of looking for visible signs of damage or faults, most of the electrical risks
can be controlled. This will need to be backed up by testing as necessary.
It is recommended that fixed installations are inspected and tested periodically by
a competent person.
The frequency of inspections and any necessary testing will depend on the type of
equipment, how often it is used, and the environment in which it is used. Records
of the results of inspection and testing can be useful in assessing the effectiveness
of the system.
Equipment users can help by reporting any damage or defects they find.
Work safely
Make sure that people who are working with electricity are competent to do the
job. Even simple tasks such as wiring a plug can lead to danger - ensure that people
know what they are doing before they start.
Check that:
■ suspect or faulty equipment is taken out of use, labelled ‘DO NOT USE’ and
kept secure until examined by a competent person;
■ where possible, tools and power socket-outlets are switched off before
plugging in or unplugging;
■ equipment is switched off and/or unplugged before cleaning or making
adjustments.
More complicated tasks, such as equipment repairs or alterations to an electrical
installation, should only be tackled by people with a knowledge of the risks and the
precautions needed.
You must not allow work on or near exposed live parts of equipment unless it is
absolutely unavoidable and suitable precautions have been taken to prevent injury,
both to the workers and to anyone else who may be in the area.
Underground power cables
Always assume cables will be present when digging in the street, pavement or near
buildings. Use up-to-date service plans, cable avoidance tools and safe digging
practice to avoid danger. Service plans should be available from regional electricity
companies, local authorities, highways authorities, etc.
Overhead power lines
When working near overhead lines, it may be possible to have them switched off if the owners are given enough notice. If this cannot be done, consult the owners

about the safe working distance from the cables. Remember that electricity can
flash over from overhead lines even though plant and equipment do not touch
them. Over half of the fatal electrical accidents each year are caused by contact
with overhead lines.

Mac : can you put the ( HSE ) stuff in the Doc , Useful Information for Apprentices , please Sorry about that . Amberleaf

 

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Definitions : Earth Fault Current :
A Fault Current which flows to Earth ,

Earth Fault Loop Impedance :
The Impedance of the Earth Fault Current Loop starting and ending at the point of the Earth Fault .
This Impedance is denoted by ( Zs )
The Earth Fault Loop comprises the following , starting at the point of Fault :
* the Circuit Protective Conductor ,
* the Consumers Earthing terminal and Earthing Conductor ,
* for TN-Systems , the return path ,
* for TT and IT Systems , the Earth return path ,
* the path through the Earthed Neutral point of the Supply Transformer and the Transformer Winding ,
* the Phase Conductor from the Transformer Supply to the point of Fault ,

BS 7671:2008
(i) The Electrical Installation Certificate required by part 6 : should be made out and signed or otherwise
authenticated by a competent person or persons in respect of the design, construction, inspection and testing of the work

(ii) The Minor Works Certificate required by Part 6 : should be made out and signed or otherwise authenticated by
a competent person in respect of the design, construction, inspection and testing of the minor work.
(iii) The Periodic Inspection Report required by part 6 : should be made out and signed or otherwise authenticated
by a competent person in respect of the inspection and testing of an installation
(iv) Competent persons will, as appropriate to their function under (i) (ii) and (iii) above, have a sound
knowledge and experience relevant to the nature of the work undertaken and to the technical standards set
down in these Regulations, be fully versed in the inspection and testing procedures contained in these
Regulations and employ adequate testing equipment
(v) Electrical Installation Certificates will indicate the responsibility for design, construction, inspection and
testing, whether in relation to new work or further work on an existing installation .
Where design, construction, inspection and testing are the responsibility of one person a Certificate with a
single signature declaration in the form shown below may replace the multiple signatures section of the model form

FOR DESIGN, CONSTRUCTION, INSPECTION & TESTING
I being the person responsible for the Design, Construction, Inspection & Testing of the electrical
installation (as indicated by my signature below), particulars of which are described above, having
exercised reasonable skill and care when carrying out the Design, Construction, Inspection & Testing,
hereby CERTIFY that the said work for which I have been responsible is to the best of my knowledge
and belief in accordance with BS 7671 :2008, amended to .............(date) except for the departures, if
any, detailed as follows.
(vi) A Minor Works Certificate will indicate the responsibility for design, construction, inspection and testing of
the work described on the certificate.
(vii) A Periodic Inspection Report will indicate the responsibility for the inspection and testing of an installation
within the extent and limitations specified on the report.
(viii) A Schedule of Inspections and a Schedule of Test Results as required by part 6: should be issued with the
associated Electrical Installation Certificate or Periodic Inspection Report.
(ix) When making out and signing a form on behalf of a company or other business entity, individuals should
state for whom they are acting.
(x) Additional forms may be required as clarification, if needed by ordinary persons, or in expansion, for larger
or more complex installations.
(xi) The IEE Guidance Note 3 provides further information on inspection and testing on completion and for
periodic inspections ,
ELECTRICAL INSTALLATION CERTIFICATES NOTES FOR FORMS 1 AND 2
1. The Electrical Installation Certificate is to be used only for the initial certification of a new installation or
for an addition or alteration to an existing installation where new circuits have been introduced.
It is not to be used for a Periodic Inspection, for which a Periodic Inspection Report form should be used.
For an addition or alteration which does not extend to the introduction of new circuits, a Minor Electrical
Installation Works Certificate may be used.
The "original" Certificate is to be given to the person ordering the work (Regulation 632.1 A duplicate
should be retained by the contractor.
2. This Certificate is only valid if accompanied by the Schedule of Inspections and the Schedule(s) of Test
Results.
3. The signatures appended are those of the persons authorized by the companies executing the work of
design, construction, inspection and testing respectively. A signatory authorized to certify more than
one category of work should sign in each of the appropriate places.
4. The time interval recommended before the first periodic inspection must be inserted (see IEE Guidance
Note 3 for guidance).
5. The page numbers for each of the Schedules of Test Results should be indicated, together with the total
number of sheets involved.
6. The maximum prospective fault current recorded should be the greater of either the short-circuit current or
the earth fault current.
7. The proposed date for the next inspection should take into consideration the frequency and quality of
maintenance that the installation can reasonably be expected to receive during its intended life, and the
period should be agreed between the designer, installer and other relevant parties