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

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Again the extent and limitations of the report needs to be stated and recommendations of defects and their remedies should be made.
The report includes a numbering system for this purpose, as follows: 1 - Requires Urgent Attention; 2 - Requires Improvements; 3 - Requires Further Investigation; and 4 - Does Not Comply With BS 7671:2008 (although this does not necessarily imply that the electrical installation is unsafe).
Several associations and trade bodies allow the issuing of a Minor Works Certificate.
A minor works is defined as 'work which does not include the provision of a new circuit'.
Testing is still essential and a number of tests are specifically identified as essential to confirm safety.
Also included on the form is space to allow the inspector to comment on the existing installation.
In a practical sense, for most electrical contractors involved in installation testing, the most frustrating part of the job is the recording of test data onto test certificates.
Invariably, current working practices involve the printing out or copying of a certificate for all premises to be tested at the beginning of the working day.
As circuit testing is undertaken on site the electrician will then usually record details of the inspection with written information on the 'dummy' certificate.
At the end of the day, back in the office, the manually recorded results will then be transferred to an 'original' certificate for the customer.

When Must The Tests Be Carried Out ? IEC ←← Our Cousins Over the Seas Regulations’ 2392-10 / 2391-10

The International Standard IEC-603664-6 Provides Requirements for “ Initial Verification “ and “ Periodic Verification “
Of an Electrical Installation :

“ Initial Verification “ Consists of Visual Inspection & Testing , of an Electrical Installation to Determine , as far as Reasonably Practicable , whether the Requirements’ of the Other Parts of IEC-60364 have been Met , Including Requirements for the Reporting of the Testing Results ,
The Initial Verification takes Place Upon Completion of a New Installation or Completion of Additions or of Alterations to Existing Installations ,

Periodic Verification : Provides the Frequency and the Requirements’ for Periodic Verification of an Electrical Installation to Determine ,
As far as Reasonably Practicable , Whether the Installation and all its Constituent Equipments are in a Satisfactory Condition for Use ,
Including Requirements for the Reporting of the Testing Results , Chapter 7 of this Guide Reports some Consideration of Periodic Inspection ,

This Guide will Not-Consider Visual Inspections ( for example the Checking of the Method of Protection Against the Electric Shock like Barriers
And Distances , Colour and Size of the Conductors , Presence of the Diagrams , Appropriate Selection of Materials , etc . )
But will Focus on the Various Testing Regimes and the Stipulated Values which these Tests should Deliver ,

Requirements For Testing An Electrical Installation :

The Following Tests shall be Carried Out where Relevant and should Preferably be Made in the Following Sequence :

* Continuity of the Protective Conductors and of the Main and Supplementary Equipotential Bonding Conductors :
* Insulation Résistance of the Electrical Installation :
* Protection by SELV & PELV or by Electrical Separation :
* Insulation Résistance of Non-Conducting Floors and Walls :
* Verification of Conditions for Protection by Automatic Disconnection of the Supply -
( Fault Loop Impedance , Earth Résistance , RCD Tests )
* Polarity and Phase Sequence Tests :
* Functional and Operational Tests :
* Voltage Drop :

The International Standard IEC-60364-6 Requires that all Measuring Instruments and Monitoring Equipment Used for the above Tests Comply with the Series IEC/EN 61557 , if Other Testing Equipment is Used , it shall Provide the Same Degree of Performance and Safety as a Minimum ,

Electrical Systems : “ Experiment “

An Electrical System Consists of a Single Source of Electrical Energy and an Installation ,
Depending on the Relationship between the Source and the Exposed ( Conductive ) Part of the Installation to Earthing ,
The Standards define the Type of System as Follows :

TT , System : the Accessible Conductive Parts are Earthed Indepently of the Source Earth :

TT : L1 ─────────────── ------- ────────────────────
……. L2 ─────────────── ------- ────────────────────
……. L3 ── * ──────────── ------- ───*──────────────── ( Single Phase )
…….. N ── * ──────────── ------- ───*──────────────── ( PE ) – ( R ) – Earthing

Earthing Rod ,

IT – System : the Live Parts are Insulated from the Earth ( or Connected to Earth Through an Impedance Z )
The Accessible Conductive Parts are Earth Independently :

……………………………………. 3-Phase
IT : L1 … . ────────────────── -------- ────────────────
……. L2 … . ────────────────── -------────────────────
……. L3 … * ────────────────── ------- ──*────────── L3 - ( Single Phase
…….. N * ─↓──────────────── ------- ─────*─────── ( PE ) – R ( Earthing
.. ……………..... Z
Earthing

IEC ←← Our Cousins Over the Seas Regulations’ 2392-10 / 2391-10

Insulation Résistance of the Electrical Installation :

The Insulation Résistance shall be Measured between each Live Conductor and the Protective Conductor or Earth ,
In Locations Exposed to Fire Hazards , a Measurement of the Insulation Résistance between the Live Conductors’ shall be Taken
The Insulation Résistance , Measured with the Test Voltage Values Indicated in the Table below are Satisfactory if each Circuit , with the Appliances Disconnected , has an Insulation Résistance Not-Less than the Appropriate Value given in the same table ,

Nominal Circuit ………………………….. Test Voltage …………………………… Insulation Résistance
Voltage ………………………………………. d.c. ………………………………….
────────────────────────────────────────────────────────────────
SELV , PELV ………………………………… 250 v ……………………………………… ≥ 0.5MΩ
( ≤ 50 v a.c. ≤ 120 v d.c. )
────────────────────────────────────────────────────────────────
Up to & including 500 v ……………………… 500 v ……………………………………... ≥ 1 MΩ
( including FELV )
────────────────────────────────────────────────────────────────
Above 500 v …………………………………… 1000 v …………………………………….≥ 1 MΩ
────────────────────────────────────────────────────────────────

Typically for 230 / 400 v Circuits ( Excluding SELV & PELV ) IEC 60364-6 Requires that the Insulation Résistance at a Test
Voltage of 500 v d.c. shall be 1MΩ as a Minimum :

NOTE: Where Surge Protective Devices ( SPDs ) are Likely to Influence the Test or be Damaged ,
Such Equipment shall be Disconnected before Carrying Out the Insulation Résistance Test , Where it is Not Reasonably Practicable to Disconnect such Equipment ( e.g. in Case of Fixed Sockets-Outlets Incorporating an ( SPD ) the test Voltage for the Particular Circuit may be Reduced to 250 v d.c. , but the Insulation Résistance must have a Value of at Least 1MΩ

Protection by SELV , PELV or by Electrical Separation : 2392-10 / 2391-10

Even if the Automatic Disconnection of Supply by Circuits-Breakers , Fuses and RCDs , is Normally the most Common Protection Method . there are Other Protection Methods like Protection by SELV , PELV or be Electrical Separation or by Non-Conducting Floors and Walls ,

Only for these Cases shall the Separation of Live Parts from those of Other Circuits , be Confirmed by a Measurement of the Insulation Résistance , The Résistance Values Obtained must be in Accordance with table :
Below there is an Example of the Measured of Insulation Résistance to Confirm the Separation of Live Parts from those of Other Circuits :

Test Instrument : (1) One Lead On ( Between the Output of the Transformer ) 2-Wires
Test Instrument : (2) One Lead On ( And the Other Live-Parts – for SELV / PELV )
( And the Equipotential Bonding Rads ( SELV Only )

Insulation Résistance of Non-Conducting Floors and Walls :

When it is Necessary to Comply with the Requirements of the Protection by Non-Conducting Locations , the Floor and Wall Insulation Résistance / Impedance shall be Tested
In Part 6 of IEC 60364 Methods for Measuring the Insulation Résistance / Impedance of Floors and Walls are given as Example ,

IEC ←← Our Cousins Over the Seas Regulations’ 2392-10 / 2391-10

Verification of Conditions for Protection by Automatic Disconnection of the Supply :

Automatic Disconnection of the Supply is Required where a Risk of Harmful Pathophysiological Effects to a Person may arise due to a Fault as a Result of the Value and Duration of the Touch Voltage ,
The Verification of the Efficacy of the Measures for Protection against Indirect Contact by Automatic Disconnection of Supply is Treated below :

In Case of TN-systems :

According to the International Standard IEC 603664 , for TN- system the Characteristics of the Protective Device and the Circuit Impedance shall fulfil the following Requirements :
( Zs x Ia ≤ Uo )
Zs : is the Fault Loop Impedance in Ohms ,
Uo is the Nominal Voltage between Phase to Earth ( Typically 230 V AC for Single Phase & Three Phase Circuits ,
Ia is the Current Causing the Automatic Disconnection of the Protective Device within the Maximum Disconnecting Times Required by IEC 60364-41 that are :

- 400 ms for Final Circuits Not Exceeding 32A ( at 230 / 400V ac )
- 5s for Distribution Circuits and Circuits Over 32A ( at 230V / 400V ac )

The Compliance with the above rules shall be Verified by :
(1) Measurement of the Fault Loop Impedance ( Zs ) by Loop Tester :
(2) Verification of the Characteristics and / or the Effectiveness of the Associated Protective Device , This Verification shall be Made :

 

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- for Circuit-Breakers and Fuses , by Visual Inspection ( i.e. Short Time or Instantaneous Tripping Setting for Circuit-Breakers ,
Current Rating and Type for Fuses )
- for RCDs , by Visual Inspection and Test using RCD Testers Recommending that the Disconnecting times mentioned above are met ,

For Instance in a TN-system with nominal mains Voltage Uo = 230 V Protected by General Purpose gG fuses or MCBs ( Miniature Current Breakers ) required by IEC 898/ EN 60898 , the ( Ia ) and Max ( Zs ) Values could be :

Protection by ( gG fuses )
With Uo of 230 V
Rating ( A ) ……. Disconnection …………. Disconnection ( Regs BS – table 41.4
………………….. time 5s ………………….. tine 4s
……………….. Ia … Zs …………………. Ia … Zs ……
……………….. (A) .. (Ω) …………………(A) .. (Ω) …..
6 ……………… 17 ... 13.5 ……………….. 38 … 8.52 ….
10 ……………...31 ... 7.42 ……………….45 .. .5.11 ….
16 ……………...55 ... 4.18 ………………..85 … 2.7 ….
20 ……………...79 ... 2.91 ………………..130 …1.77 ….
25 ……………..100 ... 2.30 ……………….160 …1.44 ….
32 ……………..125 ... 1.84 ……………….221 …1.04 ….
40 ……………..170 ... 1.35 ………………. --- ….. ---
50 ……………..221 ... 1.04 ………………. --- ….. ---
63 ……………..280 ... 0.82 ………………. --- ….. ---
80 ……………..403 ... 0.57 ………………. --- ….. ---
100 ……………548 ... 0.42 ………………. --- ….. ---

The most Complete Loop Testers or Multifunction Testers also have the Prospective Fault Current Measurement , in this case Prospective Fault Current Measured with Instruments must be Higher than the Tabulated ( Ia ) of the Protective Device Concerned ,

Below is a Practical Example of Verification of the Protection by MCB in a TN-system ,
According to the International Standard IEC 60364 ,

Max Value of ( Zs ) for this Example is 1.44Ω ( MCB / 16A ) Characteristic C , THE Instrument reads 1.14Ω ( or 202A on Fault Current Range ) it means that the Condition ( Zs x Ia x ≤ Uo is Respected ,
In fact the ( Zs of 1,14Ω is Less than 1.44Ω ( or the Fault Current of 202A is more than ( Ia ) of 160A .
In Other words , in case of Fault between Phase & Earth , the Wall Socket Tested in this Example is Protected because the MCB will Trip within the Disconnection time Required ,

L3 -
N -
PE -

17th Edition - & -
Chapter 41 :
Protective Measure Against Electric Shock :

Under Some Sub-Cat ; ( Basic Protection ) ( Fault Protection ) ( Additional Protection )
Part-4 Protection for Safety

411.2 Requirements for Basic Protection :
411.3 Requirements for Fault Protection :
411.3.3 Additional Protection :

Now Designated ↔ Basic Protection , ( 410 ) ( i ) “ Insulation “ Applied to Live Parts “ Preventing Touching Live Conductors , Protection against Electric shock under fault-free conditions .

Note : for Low-Voltage Installations , systems and Equipment , Basic Protection generally corresponds to Protection against Direct Contact ,
That is “ Contact of Persons or Livestock with Live-Parts :

Now Designated ↔ Fault Protection ( 410 ) ( ii ) “ Protective Earthing “ Automatic Disconnection of Supply , ( ADS ) ←
Protection against Electric shock → Under Single-Fault Conditions ←

Note : for Low-Voltage Installations , systems and Equipment , Fault Protection generally corresponds to Protection against Indirect Contact ,
Is “ Contact of Persons or Livestock with → Exposed-Conductive-Parts which have become Live Under Fault Conditions ← :

415 : Additional Protection : Is Not Defined in Part 2 of the Regs , it is Detailed in Section ( 415 ) ←

Additional Protection against Electric shock can be Provided by Either !
( 415.2 ) Supplementary Equipotential Bonding ,
( 415.1 ) Additional Protection : Residual Current Devices ( RCDs ) Not Exceeding 30mA ↔ Operating time Not Exceeding 40mS

Protective Measures Against Electric Shock ,

* ( Basic and Fault Protection )
Extra Low-Voltage : SELV / PELV
SELV , is a Safety Isolation Transformer ( No Earth Provisions on the Secondary Side of the Transformer ) 230V- P │ ↔ │S- 12V a.c.
PELV , The Earth Provisions Continues through to the Load Side :

When it comes to Inspection there’s several things your got to check ? the First of those is does the Location your in which in this Location is the Bathroom has Requirements for SELV or PELV ,

Part 7 :Special Installation or Locations

You Need to Look up : P-169 / fig 701.2

( 701.55 ) In a Room Containing a Bath or Shower ; Suitable Fixed Current-Using Equipment , ( in Zone 0 , SELV / Remember Not PELV ,
Remember SELV is Located Outside the Zones ,
( iii ) SELV at a Nominal Voltage Not Exceeding 12V ac rms or 30V ripple-free d.c.

Zone O , Area Within the Bath or Shower : ▪▪▪
Zone 1 , Area Directly above Barth or Shower : ( Up to 2.25m Above the Finished Floor ▪▪▪
Zone 2 = Defined as Area Within 0.60m Circumference from the Bath or Shower : ▪▪▪

Regs : 17th , Socket-Outlet are Prohibited within a Distance of ( 3 m ) Horizontally from the Boundary of Zone 1 , This One will Come Up : p–167 ▪▪▪
Or ( FSU ) for Electric Towel Rail : ( RCD / Spur 30mA )

Arm’s Reach : N/A Accessibility in Zone O / Zone 1
N/A Electrical Equipment in Bathroom , ↔ 1 or more ( RCD 30mA “ Including Lighting Circuits “ ▪▪▪
( 701.512.2 ) IPX7 (i) Zone O / IPX4 , (ii) Zone 1 / 2 ( Lighting Bathroom ) ▪▪▪

( 702.522.24 ) Junction boxes : This One will Come Up : p–167 ▪▪▪▪
A Junction box shall Not be Installed in Zone 0 or 1 but in the case of SELV Circuits it is Permitted to Install Junction boxes in Zone 1

Termed an “ Extraneous Conductive Part “ Water Pipe , ( Not Part of an Electrical System / Equipment )

Functional Extra-Low Voltage ( FELV ) Exposed Conductive Parts of an FELV System are Connected to the Protective Conductor of the Primary Circuit of its Source : ( 411.7 )
Following shall be Used as Source of FELV , Transformer with Separations’ between Windings’ :

Heath and Safety 2392-10

The Electricity at Work Regulations 1989

12 Means for Cutting off the Supply and for Isolation ,
13 Precautions for work on Equipment made Dead ,
14 Work on or near live Conductors ,

12 Means for Cutting off the Supply and for Isolation

12.- (1) Subject to paragraph (3), where necessary to prevent danger , suitable means
( including , where appropriate , methods of identifying circuits ) shall be available for-
(a) cutting off the Supply of Electrical energy to any Electrical equipment ; and
(b) the isolation of any Electrical equipment .
(2) In paragraph (1),” isolation “ means the disconnection and separation of the
electrical equipment from every source of electrical energy in such a way that this
disconnection and separation is secure .
(3) Paragraph (1) shall not apply to electrical equipment which is itself a source of
electrical energy but, in such a case as is necessary , precautions shall be taken to prevent ,
so far as is reasonably practicable , danger .

Electrical Test Equipment for use by Electricians ( GS-38

Guidance on Safe Isolation Procedures for Low Voltage Installations :

Domestic : the Fundamental Principle of Safe Isolation Practice is that the Point of Isolation should always be under the Control of the Person who is carrying out the work at all Times : ( Locking Off )

For work on LV Electrical Equipment or Circuits , it is Important to Ensure that the Correct Point of Isolation is Identified ,
An Appropriate Means of Isolation is Used , and the Supply Cannot Inadvertently be Reinstated while the work is in Progress ,

Warning / Caution Notices should also be Applied at the Point(S) OFF Isolation , and the Conductors must be Proved to be Dead
At the Point of “ Work “ before they are Touched ,

Firstly you Must Guarantee the Point of Isolation is Correct , that the Circuit that your need to working on , making Sure that Correct Identification was Carried Out : ↔ “ Never Take for Granted “ ↔ the Circuit Chart or Identification of the Device :

( Isolation of Individual Circuits Protected by Circuit-Breakers )
Where Circuit-Breakers are Used , the Relevant Device should be Locked-Off Using an Appropriate Locking-Off Device
With a Padlock which can Only be Opened by a Unique Key or Combination , The Key or Combination should be Retained by the Person Carrying Out the Work .

The Principle is that Each Person carrying out such work should have Control of their own Point(s) of Isolation and Not Rely
On Others to Prevent Deliberate or Inadvertent Energization ,

( Typical Devices for Proving Dead ) “ Remember “ 2392-10 you’ll be Asked some of these Q/A “

The Procedure for Proving Dead should be by Use of a “ Proprietary Test Lamp or Two-Pole Voltage Detector as Recommended
In Guidance Note GS-38 ,
Electrical Test Equipment for Use by Electricians , Non-Contact Voltage Indicators ( Voltage Sticks ) and Multimeters should Not be Used ,

The Test Instrument should be Proved to be Working on a Known Live Source or “ Proprietary Proving Unit , before and after Use ,
All Conductors of the Circuit , Including the Neutral , should be Tested and Proved Dead :

 

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Domestic Electrician : 2392-10

Note : in TT Systems , the Incoming Neutral Conductor Cannot Reliably be Regarded as being at “ Earth Potential :
This Means that for TT Supplies , a Multi- Pole Switching Device which Disconnects the Phase-Neutral Conductors
Must be Used as the Means of Isolation .

Note : in IT Systems , All Poles of the Supply Must be Disconnected , in these Circumstances , Single-Pole Isolation ,
Such as by Fuses or Single-Pole Circuit-Breakers , “ is Not Acceptable “

Temporary Disconnection of Incoming Supply :

For Some Type of Work on Existing Installations , such as the Replacement of Main Switchgear , Consumer Units etc .
It is necessary for the Distributors Service Fuse(s) to be withdrawn in order to Disconnect the Incoming Supply for
The Purpose of Isolation ,

Legally , Service Fuses can be Withdrawn Only by the Distributor , or by those they have Expressly Authorized to Carry Out such Work ,

Note : Some DBs are Manufactured with “ SLIDER SWITCHES “ to Disconnect the Circuit from the Live Side of the Circuit-Breaker
These Devices should “ NOT “ be Used as a Means of Isolation for Circuits , as they “ DO NOT “ meet The Requirements for Isolation
And the “ Wrong Switch “ Could Easily be Operated on Completion of the Work :

Domestic Electrician : 2392-10
Additional Precautions :

New Installations ,

New Installations can be a Particular Hazard as some of the Circuits or Equipment may require to be Modified after the
Installation has been Energized ,
It is therefore Important that every Protective Device is Correctly Identified at each Distribution Board before any Energizing takes place ,
And Safe Isolation Procedures , such as Locking-Off Circuit-Breakers as Particularly where a Number of Electricians are working on the same Installation ,

Alterations & Additions :

Alterations & Additions to Existing Installations can also be Particularly Hazardous , Records including Circuit Identification may not be Available ,
Or may be Inadequate or Incorrect , it is therefore Particularly Important to ensure that Circuits to be worked on has been Correctly Identified for Isolation Purposes ,

Neutral Conductors :

Care should be taken when working on Neutral Conductors of Circuits , The Practice of “ Borrowing Neutral , ( 314.4 ) i.e. making
Use of the Neutral of one of the Circuit for use on another Circuit , is Not Permitted by BS-7671 , this Dangerous Practice , however , may still be Encountered ,
Lighting & Control Circuits’ are the most Common Example : where this Practice is found , in these Circumstances , the Neutral
Conductor can become Live when the Conductor is Disconnected , if a Load is Connected to that Circuit ,
It is also Difficult to Identify Specific Neutral Conductor in “ Bunches “ of Single-Core Cables , such as where Enclosed in Trunking or Conduit ,
And care should be taken when severing such Cables that the correct Conductor has been Identified ,

Guide To Isolation Procedure : GS-38 / 2392-10 ( this will cover your Butt )

Pocket Size Guide ,

Step (1) : ( Locked Off )
Check it is Safe and Acceptable ( with the Occupier / User ) to Isolate, if the Isolator is an Off-Load Device ,
Remove the Load . Open the Means of Isolation for the Circuit(s) to be Isolated and Secure the Isolating Device in the Open Position with a
Lock or Other Suitable Means :

Step (2) : ( Proving Unit )
Prove the Correct Operation of a Suitable Voltage Detection Instrument , See Note (v) Guidance on Voltage Detection Instruments is given in
HSE Guidance Note GS-38 – Electrical Test Equipment for use by Electricians : against source ,

Step (3)
Using a Voltage Detection Instrument , Check that there is No Dangerous Voltage Present on any Circuit Conductor to be
Worked on , it is Important to Confirm that Conductors’ are Not Energized , Example ; due to a Wiring Fault , Check Terminal
Voltage between : (1) - ( Earth & Phase ) (2) – ( Neutral & Phase ) (3) – ( Earth & Neutral ) ,

Notes :
(a) in practice the equipment being worked on is likely to be remote from the consumer unit , example ,
A socket-outlet located remotely from the means of isolation , in this case it is necessary to check
that all the sockets-outlet contact terminals are “ Dead “
(b) when checking for a voltage between an earth terminal and live ( including neutral ) terminals ,
The test probe should make contact with the earth terminal first , to reduce the risk of the remaining
Probe becoming live ,

Step (4)
Prove the voltage detection instrument again against the known source to check that it was functioning correctly
When the circuit(s) were tested for the presence of voltage .

Notes :
(1) The Electricity at Work Regulations 1989 , require precautions to be taken against the risk of death or personal injury
from Electricity at Work activities Regulations ( 12 ) requires that , where necessary to prevent Danger : a suitable means is
available for cutting off the supply of Electrical Energy to any Electrical Equipment ,

Proving Dead Isolated Equipment or Circuits :

It is Important to ensure that the correct point of Isolation is Identified before Proving Dead ,
Following Isolation of Equipment or Circuits and before starting work it should be proved that the Parts to be worked on and those nearby , are Dead , it should never be Assumed that Equipment is Dead because a Particular Isolation Device has been Placed in the OFF Position ,

 

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In the Case TT Systems : 2392-10 ( this will come up on the 17th Edition , -&- )

According to the International Standard IEC 60364 , for TT Systems the Characteristic’s of the Protective Device and the Circuit Resistance shall fulfil the following Requirements : ( Ra x Ia ≤ 50V )
Where :
( Ra ) is the Sum of the Resistance in Ω of the local Earth System and the Protective Conductor for the Exposed Conductive Parts ,
( 50 ) is the Maximum Safety Touch Voltage Limit ( It can be 25v in Particular Cases like Construction Sites , Agricultural Premises , etc . )
( Ia ) is the Current Causing the Automatic Disconnection of the Protective Device within the Maximum Disconnecting Times Required IEC 60364-41 :
-- 200mS for Final Circuits Not Exceeding 32A ( at 230 / 400 AC )
-- 1000mS for Distribution Circuits & Circuits over 32A ( at 230 / 400 AC )

The Compliance with the above rules shall be Verified by :
(1) Measurement of the Résistance ( Ra ) Regs : BS – 411.5.3. ↔ of the local Earth System by Loop Tester or Earth Tester .
(2) Verification of the Characteristics’ and / or the Effectiveness of the RCD Associated Protective Device ,

Generally in TT Systems , RCDs shall be Used as Protective Device and in this Case , ( Ia ) is Rated Residual Operating Current ( I∆n ) ,
For Instance in a TT System Protected by a RCD the Max ( Ra ) Values are :

Rated Residual Operating :
………Current ………………….. 30 ----- 100 ----- 300 ----- 500 ----- 1000 ----- mA
………. ( Ra )
( with touch voltage of 50V ) … 1667 ----- 500 ----- 167 ----- 100 ----- 50 ----- Ω
………. ( Ra )
( with touch voltage of 25V ) … 833 ----- 250 ----- 83 ----- 50 ----- 25 ----- Ω

Practical Example of Verification of the Protection by RCD in a TT System According to the International Standard IEC 60364 ,

The Standard Describes two methods for Testing the Résistance ( Ra )

- Volt-Ampere Method , Using Classical Earth Résistance Testers or the most Complete Multifunction Testers by sticking Two Auxiliary Earth Electrodes into the Ground . ( R – PE ) ( RCD 30 mA )

Fault Loop Impedance Method ( Loop Tester ) Regs BS- 6132.9 : the IEC 60364-6 Describes a Safe and easy Method to Test Earth Résistance
Where in a TT System , the Location of the Installation ( e.g. in Towns ) does Not Practice allow the two Auxiliary Earth Spikes to be Inserted into the Ground ,
This Method consists of the Measurement of the Fault Loop Impedance with a Loop Tester or a Multifunction Tester , in a TT Systems
Will in Practice give the Earth Résistance , ( RCD 30 mA )

For these Example the Max Permissible Value is 1667Ω ( RCD = 30mA and Contact Voltage Limit of 50V )
The Instruments’ Reads 12.74Ω : thus the Condition ( Ra ≤ 50 / Ia ) is Respected , However , considering that the RCD is Essential for Protection , it must be Tested as Follows :

Operation of Residual Current Devices ( RCDs ) in TT System :
Given that when the Protective Device is an RCD , ( Ia ) is Typically ( 5 ) times the rated Residual Operating Current ( I∆n ) then the RCD must be Tested Using RCD Testers or Multifunction Testers Recommending that the Disconnecting Times Required in IEC 60364-41 are Confirmed ,

The RCD Testers or Multifunction Testers can Perform the Tests for Single-Phase and Three-Phase RCDs by Measuring the Tripping Time , in TT System at 230 / 400V , the Tripping Time Measured by an RCD Tester or a Multifunction Tester shall be Lower than the Maximum Disconnecting Times as Defined by IEC 60364-41 that are :

- 200 mS for Final Circuits Not Exceeding 32A :
- 1000 mS for Distribution Circuits & Circuits Over 32A :

It is also Good Practice to Consider even more Stringent Trip Time Limits , by Following Standard Values of Trip Times at ( I∆n ) Defined by IEC 61009 ( EN 61009 ) and IEC 1008 ( EN 61008 ) These Trip Time Limits are listed in the Table Below :

Type of RCD …………………………………… Test at I∆n
General ( G) …………………………… 300mS Max . allowed value :
────────────────────────────────────────── ( Regs , BS – p-243 ,
General ( S ) …………………………… 500mS Max . allowed value :
………………………………………….. 130mS Min . allowed value :

Note : These Tripping Time Values are Applicable to RCDs Correctly Installed According to the Manufacturer Specifications :

( Old ) General Purpose RCDs to BS-4293 : Operating time less than 200mS : Remember ↔ ↔ ( BS- )
RCDs to BS-EN 61008 & BS-EN 61009 , Operating time below 300mS : Remember ↔ ↔ ( BS-EN )

Remember ↔ ↔ Note 2 Where ( Ra ) is Not known , it May be Replaced by ( Zs ) Regs : 411.5.3 )
411.5.3 ) (ii) Ra x I∆n ≤ 50V , ( Ze = Ra , electrode : Max permitted is 1666Ω , based on Not allowing the Voltage to Rise above ( 50V )

For IT Systems : IEC ←← Our Cousins Over the Seas Regulations’ 2392-10 / 2391-10

Compliance with the rules of IEC 60364-4-41 shall be Verified by Calculation or Measurement of the Current in case of a first Fault at the Line Conductor or at the Neutral :
Where similar conditions to TT or TN- Systems Occur , in the event of a second Fault in another Circuit , Verification is made as for TT or TN- systems as described above ,

Note : During the Measurement of the Fault Loop Impedance , it is necessary to establish a connection of negligible Impedance between Neutral Point of the System and the Protective Conductor Preferably at the Origin of the Installation or ,
Where this is Not Acceptable , at this Point of Measurement ,

Measurement of the Earth Electrode Résistance :
The International Standard IEC 60364-6 Provides Information Regarding the Measurement of the Résistance of an Earth Electrode for TT, TN and IT Systems , this Measurement shall be made by the Volt-Amperometric Method Using Two Auxiliary Earth Electrodes ,
The Instrument that covers , this Requirement is the Earth Tester : ( Measurement of the Earth Electrode Résistance )

( Earth Electrode , under Test ) 3 – Leads Used , 0ne on Earth Electrode
( Auxiliary Earth Electrodes , ) 0ne on each Aux Electrode ,

Note : The Auxiliary Earth Electrodes must be Placed at Sufficient Distance from the Earth Electrode Under Test in Order to
Avoid Overlapping of the Résistance Areas of the Electrodes ,

Polarity & Phase Sequence Tests :

Where the Standard Prohibits the Use of Single-Pole Switching Devices for the Neutral Conductor ,
A Test shall be made to Verify that all such Devices are Used Only for Line Conductor(s) ,
Where the Rules Require Double Pole-Switches , a Test shall be made to Verify that the Poles of such Devices are Connected
Correctly to the Appropriate Conductor ,

In the case of Multiphase Circuits it shall be Verified that the Phase Sequence is Maintained ,
In Particular a Test shall be made to Verify that the Devices ( i.e. Motors ) are Connected in the Correct Phase Sequence by a Phase Rotation Tester ,
Two Example : a Polarity Test Determine the Phase Conductor Using Digital Multimeter as a Voltmeter ,
( “ DEAD TEST “ Multimeter : One Lead on Phase Conductor / Other Lead on Earth Terminal : ( PE )
( Motor 3-Phase ) 3 – Leads , 1 / L1 , 1 / L2 , 1 / L3 , ( Remember Contacts are Open ,

Functional Tests :

Assemblies , such as Switchgear and Control gear Assemblies , Drives , Controls , and Interlocks , shall be Subjected to a Functional Test to Show that they are Properly Mounted , Adjusted and Installed in Accordance with the relevant Requirements of the IEC 603664 , Protective Devices shall be Submitted to Functional Tests , if Necessary , in Order to Check if they are Properly Installed and Adjusted ,

The fundamental rule of protection against electric shock, according to IEC 61140, is that
hazardous-live-parts must not be accessible and accessible conductive parts must not be
hazardous live, neither under normal conditions nor under single fault conditions.

 

[castlon11]

“ Rcd's “


Surface run cables do not require RCD protection. OSG p22

This statment conflict's with so many other regulations when taken out of context.

Other than this, very nice post, thanks

 

[amberleaf]

Additional Protection : ( Solar Photovoltaic ( PV ) Regs p-22

Solar Technology recommends always installing an RCD as additional protection in order to achieve the
highest possible degree of safety. It can also offer the function of an all-pole disconnecting switch, which is frequently required due to other reasons or regulations.
( South - 30º / 20V per-panel )
Remember Chaps : if your working on Mains ( 712.410.3 ) what the 17th is telling you is ? that if your working on ( PV )
After Isolation the ( DC ) is LIVE ←← ( This will come Up 17th -&- )
AC : day / Light On / Off , DC : Night Time Off / On
They will ask about the DC :side ( DC Side Class II ) WHEN Main Power is Isolated !! you will have to Isolate the DC Side as well ,
- Mains through an Isolation Switch ↔ ( a Must Warning Labels must be Placed ) ↔ Inverter > AC / DC , through an Isolation Switch on the DC Side ( if Used MCB ( B / Type )

( This will be Handy for , 17th Edition -&- )

Bath & Shower Rooms
All Electrical Equipment must be accessible for operation, Inspection & Testing , maintenance and repair. 132.12 :
Zone 0
Zone 0 for a bathroom is the area inside the bath. , 701.32.2
Zone 0 for a shower room is the area inside the shower basin. If there is no shower basin, zone 0 is 10cm high from the finished floor level and extends to 1.2m around the fixed shower head. 701.32.2
Electrical Equipment installed within zone 0 must be at least IPX7. 701.512.2
Only switches that are built into fixed Electrical Equipment and the insulated pull cords of pull cord switches are permitted in zone 0. No other switches or accessories are allowed. 701.512.3
Only SELV equipment not exceeding 12v ac or 30v dc is permitted in zone 0. The SELV equipment must be fixed and permanently connected with the transformer and isolator outside zones 0, 1 & 2. 701.55
Zone 1
Zone 1 for a bathroom is the same width as zone 0 (the width of the bath) extending to 2.25m above the finished floor level. 701.32.3
Zone 1 for as shower room is 2.25m from the finished floor level or the height of the fixed shower head from the finished floor level if more than 2.25m, and the width of the shower basin. If the shower has no basin then zone 1 extends to 1.2m around the fixed shower head. 701.32.3
If the space under the bath or shower basin is accessible without the use of a tool it is classed as zone 1, otherwise it is not considered to be a zone. 701.32.3
Zone 1 is separate from zone 0. 701.32.3
Electrical equipment installed within zone 1 must be at least IPX4 701.512.2
Only switches that are built into fixed electrical equipment, the insulated pull cords of pull cord switches and switches of SELV circuits not exceeding 12v ac or 30v dc are permitted in zone 1. The SELV transformer and isolator must be outside zones 0, 1 & 2. No other switches or accessories are allowed. 701.512.3
Showers & shower pumps, extractor fans , electric towel rails, whirlpool units, water heaters, lights and SELV or PELV equipment not exceeding 25v ac or 60v dc are permitted in zone 1. All equipment must be fixed and permanently connected , The SELV or PELV transformer and isolator must be outside zones 0, 1 & 2. 701.55
Zone 2
Zone 2 for a bathroom is the same height as zone 1 (2.25m) extended to 0.6m around the bath. 701.32.4
Zone 2 for a shower room is the same height as zone 1 extended to 0.6m around the shower basin. If there is no shower basin zone 2 is replaced by zone 1 extended to 1.2m around the fixed shower head. 701.32.4
Electrical equipment installed within zone 2 must be at least IPX4 excluding BS EN 61558-2-5 shaver supplies where direct spray from a shower will not occur. 701.512.2
Only switches that are built into fixed Electrical equipment the insulated pull cords of pull cord switches, BS EN 61558-2-5 shaver units and socket outlets and switches of SELV circuits not exceeding 12v ac or 30v dc are permitted in zone 2. The SELV transformer and isolator must be outside zones 0, 1 & 2. No other switches or accessories are allowed. 701.512.3
BS-7671 does not list permitted current using equipment for use in zone 2.
The extent of the zones in a bath or shower room can be limited by floors, ceilings and walls. For more detailed information see BS-7671 diagrams 701.1 & 701.2. Any electrical equipment installed on the surface of floors, ceilings and walls that limit a zone is subject to the requirements of that zone. 701.32.1
Electrical equipment that is exposed to water for cleaning must have a minimum degree of protection of IPX5 701.512.2

All circuits in a bath or shower room must be protected by a 30ma RCD. p6, 701.411.3.3 ,
Supplementary bonding is not required if all the extraneous conductive parts of the installation are connected to the main equipotential bonding. p-166 , 701.415.2
230v socket outlets are permitted 3m beyond the horizontal outside edge of zone 1. p-167, 701.415.3 ,
Circuits protected by electrical separation can only supply one item of equipment (excluding electric floor heating ) or one single socket. 701.413, 701.753
Electric floor heating must have a metal enclosure or sheath or a fine mesh metallic grid connected to the cpc of the supply circuit (SELV ) supplies excluded). 701.753
SELV and PELV enclosures in zones 0, 1 & 2 must be at least IPXXB or IP2X and the horizontal surface must be at least IPXXD or IP4X if accessible. Live parts must be covered by insulation that cannot be removed without force. If enclosures have to be opened for maintenance, the openings must be as small as possible with a warning that live parts can be touched. Unintentional touching of live parts must not be possible. 701.414.4.5
External influences , electrical equipment shall have at least the following degree of protection according to BS-EN 60529: (i) Zone O , IPX8 (ii) Zone 1 , IPX4 , IPX5 , where water jets are likely to occur for cleaning purposes , (iii) Zone 2 , IPX2 , for indoor locations , IPX4 for outdoor locations , IPX5 , where water jets are likely to occur for cleaning purposes , 702.512.2 .

Junction boxes , A junction box shall not be installed in zone O or 1 , but in the case of SELV circuits it is permitted to install junction boxes in Zone 1 , 702.522.24 ,

Sample Questions – 2392-10
Fundamental Inspection , Testing & Initial Verification – paper ( 4 )

1-A , 2-D , 3-C , 4-C , 5-C , 6-A , 7-A , 8-D , 9-B , 10-A , 11-B , 12-D , 13-C , 14-A , 15-B , 16-C , 17-D , 18-B ,
19-A , 20-D , 21-A , 22-D , 23-A , 24-C , 25-D , 26-B , 27-B , 28-B , 29-D , 30-D ,

Your Score should be 30 out of 30 :

Earth Electrode Résistance : GN-3 ( 2392-10 . Q/A some where a long the line some will come up , -&-

Measurement by Standard Method

( 612.7 ) When measuring earth electrode résistance to earth where low values are required ,
( 542.1 ) As in the earthing of the Neutral point of the transformer or generator , test method ( 1 )
( 542.2 ) below may be used ,

Instrument : Use an Earth Electrode Résistance Tester for this Test , Section 4.6

Earth Electrode Résistance Testers :
This may be a four-terminal instrument ( or a three-terminal one where a combined lead to the earth electrode would not have a significant Résistance compared with the Electrode Résistance ) so that the Résistance of the test leads and temporary spike
Résistance can be eliminated from the test results ,

Test method (1)
Before this test is undertaken , the Earthing Conductor to the Earth Electrode must be “ Disconnected “ either at the Electrode or ←← at the Main Earthing Terminal to ensure that all the Test Current Passes through the Earth Electrode Alone , ←←
This will leave the “ Installation Unprotected against Earth Faults “ , ←←

SWITCH OFF SUPPLY BEFORE DISCONNECTING THE EARTH : ←←←

( 542.2.2. ) The Test should be carried out when the ground conditions are least favourable , such as during dry weather ,

The test requires the use of two temporary test spikes ( Electrodes ) and is carried out in the following manner ,

Connection to the earth electrode is made using terminals C1 and P1 of a four terminal earth tester .
To exclude the résistance of the test leads from the résistance reading , individual leads should be taken from these terminals and connected separately to the electrode . if the test lead résistance is insignificant , the two-terminals may be short-circuited at the tester and connection made with a single test lead , the same being true if using a three-terminal tester . connection to the temporary spikes is made as

Test Instrument : temporary test electrodes 3-Test Leads , ( Green .C1 ↔ *─ Link out .P1 *─ ) ( Black . P2 *─ ) ( Red . C2 *─ )

AFTER COMPLETION OF THE TESTING ENSURE THAT THE EARTHING CONDUCTOR IS RECONNECTED : ←←←

 

[amberleaf]

TN-S System ( Single Phase ) Testing for ( Ze ) : What Could Happen !!!!!

One of the most Fundamental Differences’ between the Testing on a Initial Verification and a Periodic is that Testing for Initial Verification
Is to Certified that the Installation Complies with BS-7671

Where as a Periodic Report provides an Assessment of the Condition of the existing Installation , the reason for doing the ( Ze ) Testing now before Continuing with our Inspection , if there No Earth Facilities for this Installation then we have a Dangers Situation and we would have Severe Limitations on the other Tests , Continuing with the Tests would only prove Inaccurate
Readings and Only be Dangers to undertake ,

TN-S System ( Single Phase )
Supply : ↔ Source of Energy → │ → Installation

L , N , E ↔ Nil ↔ Exposed Conductive Parts :

Note: Each circuit may have more than one reason for additional protection by 30mA RCD e.g.: firstly because of the equipment i.e.: a socket outlet and secondly because of the cable installation method. Additional protection is provided as additional protection. It does not obviate
the need for circuit protection by circuit breakers or fuses.

Regulation 411.3.3 socket outlets with a rated current not exceeding 20A that are for general use by ordinary persons (exemption may be permitted).

* Regulation 701.411.3.3 Additional protection shall be provided for all circuits of the location by use of one or more 30mA RCD.
* Regulations 522.6.6 : 522.6.7 : 522.6.8 cables concealed in a wall or partition at less than 50mm depth and without earthed mechanical protection e.g. conduit.

* Regulation 314.1 Every installation shall be divided into circuits as necessary to avoid danger and inconvenience in the event of a fault, take account of danger that may arise from the failure of a single circuit such as a lighting circuit,
reduce the possibility of unwanted tripping of RCDs etc.


* Regulation 314.2 Separate circuits to be provided for parts of the installation that need to be separately controlled in such a way that those circuits are not affected by the failure of other circuits.

* Regulation 560.7.1 Chapter 56 circuits for safety services shall be independent of other circuits.
In addition Chapter 51 requires designers/installers to take account of all relevant British Standards and manufacturers instructions. For example BS5839

Part 6 is the British Standard for fire detection and alarm systems in dwellings. It states that power supplies to Grade D smoke alarms should be an independent circuit at the consumer unit, or a separately electrically protected local lighting circuit.

( With - 30mA RCDs Taking into account 3.14.1 : 3.14.2 : )

Domestic Inspection & Testing : ( 2392-10 , New Installation , Not been Energized yet )
Continuity of Radial Circuit Protective Conductors’ :
Dead Test ↔ GN-3 “ Test Prior to the Installation being Energized “

When you look at the Test Results Section on the Installation Certificate , “ Schedule of “ Schedule of Test Results “ : ( All Circuits . At Least One Circuit to be Completed ) You can see that Each of the Circuits is a Value of “ Big “ ↔ ( R1 + R2 ) Total Résistance of the Line & CPC Conductors or ( R2 ) just the Résistance of the CPC , is Required to be Recorded
( R2 ) ↔ is Generally Used for Periodic Inspection Reporting
You are Using the ( R1 + R2 ) Test Method : ←

They are a Number of Advantages to this Test Method , first we get the Information to Directly fill in the ( R1 + R2 ) Colum on the Test Schedule , ( 2 ) Polarity is Verified , and (3) the Method may be more Convenient than the Wander Lead method , and finally by Measuring the ( R1 + R2 ) for each Circuit we can Later Determine the Circuit Earth Loop Impedance ( Zs ) where Necessarily , so avoid the need to Perform Testing on Exposed Live Conductors , Example at Lighting Points

( 612.2.2 ) Continuity / Polarity :
(1) Here is a Cable Supplying the Upstairs Lighting Circuit , To do ( R1 + R2 ) Test , the Line & CPC Only , Together Into a Connector Block :

(2) Remember to Disconnect the Main Protective Bonding Conductor Effecting our Reading

You’ll have to go to Every Lighting Point on this Lighting Circuit and take a Continuity Reading : between the Line / CPC Conductors
With the Résistance off Test Results Null-Out ,

Your Going to take a Reading between the “ CPC “ and the “ Switch Line at the Ceiling Rose
Switch is “ ON “ Getting a Reading off ( 0.70Ω )

“ Polarity “ Can be Confirmed by Turning the Switch “ OFF “ ( you will get an Open Circuit if “ Polarity “ is Correct you have ( > 999.9 )
Don’t forget with a Two-Way and Intermediate Lighting Arrangement it will be necessary to repeat the “ Polarity “ by Operating all other Switches in turn
(3) One Lead on CPC - Insulated Crocodile Clip Green : ( the Furthest Part on the Circuit ) ← -&-
You’ll get the Highest Reading at this Point ( R1 + R2 ) -&- (4) Lead on Live / Switch Wire : Insulated Crocodile Clip , Brown
(5) Instrument on Test : you will be Recording on the Test Certificate : “ Schedule of Test Results “ Test Results ,
( All Circuits At Least One Column to be Completed ) ↔ ( R1 + R2 ) Box ↔ ( 0.8Ω )
You’ll now have to Remove the Connector Block back at the Consumer Unit : ( CCU ) for this Circuit ,
Don’t fall into the “ Trap “ off Carrying on with the Insulation Résistance Test for this Circuit because to Carry Out an
Insulation Résistance Test Correctly the Protective Bonding Conductors and all off the Circuit Protective Conductors will
Have to be Connected back Onto the Earthing Terminals , So it makes Sense to Carry on with the Continuity Tests On the Other Circuits
Before you do the Insulation Résistance Tests !!!!!!

“ Remember “ All the Main Protective Bonding Conductors Disconnected to Reduce the likely hood of Parallel Paths Effecting our Reading , -&-

“ Schedule of Test Results “

Remember : Ring-Final Circuits Only ( you only Use Little ( r1 ) Measured End to End Line , ← Loop . -&-
……………………………………….. ( you only Use Little ( r n ) Measured End to End , Neutral ← Loop . -&-
……………………………………….. ( you only Use Little ( r2 ) Measured End to End , CPC ← Loop . -&- ( End to End )


GN-3
Polarity :

The Polarity of all Circuits must be Verified before Connection to the Supply , with Either : GN-3 ( 612.6 ) -&-
An Ohmmeter or the Continuity Range of an Insulation and Continuity Tester :

Instrument : Use a Low-Résistance Ohmmeter for these Tests ,
( 612.2.1 ) The Instrument Used for low-Résistance Tests may be Either a Specialised low-Résistance Ohmmeter,
Or the Continuity Range of an Insulation and Continuity Tester , The Test Current may be d.c or a.c . it is Recommended that it be Derived from a Source with No-Load Voltage between 4V & 24V , and a Short-Circuit Current Not Less than 200mA ,

The Measuring Range should Cover the Span ( 0.2Ω to ( 2Ω ) with a Resolution of at least ( 0.01Ω ) for Digital Instruments ,

Instruments to BS-EN 61557-4 will meet the Above Requirements’ :

Ill be Shot for This !!! See you in Siberia “ I feel that Some Tutors do Not Teach the Right Things , Need to Know , my P45 ,
( Empty Barrels Make the Most Noise , )
( if you Make Everything Idiot Proof , Evolution will just Make a Better Idiot )
PS – is this Helping , you Chaps Out there , Amber

 

[amberleaf]

Schedule of Inspections : GN-3 2391-10 / 2392-10 ,

The Client ,
Certificates & Reports GN-3

( 631.1.) Following the Initial Verification of a New Installation or Changes to an Existing Installation ,
( 632.1.) an Electrical Installation Certificate , together with a Schedule of Inspections and a Schedule of Test Results ,
Is Required to be given to the Person Ordering the Work . in this context , “ Work “ means the Installation work ,
Not the work of carrying out the Inspection ( 631.2 ) and Test , likewise , following the Periodic Inspection and Testing of an Existing Installation ,
( 634.1 ) a Periodic Inspection Report , together with a Schedule of Inspections and a Schedule of Test Results , is Required to be given to the Person Ordering the Inspection ,

Sometimes the person Ordering the Work is Not the User , in such cases it is Necessary for the User ( e.g. Employer or Householder )
To have a Copy of the Inspection and Test Documentation . it is Recommended that those Providing Documentation to the Person Ordering the Work Recommend that the Forms be Passed to the User Including any Purchaser of a Domestic Property :

Electrical Installation Certificate : GN-3

Regulation ( 631.1 of BS-7671 Requires that, Upon Completion of the Verification of a New Installation ,
Or Changes to an Existing Installation , an Electrical Installation Certificate based on the Model given in Appendix 6 of BS 7671 , shall be Provided , Section ( 632 ) Requires that :
(1) the Electrical Installation Certificate be Accompanied by a Schedule of Inspections ( 632.1 )
And a Schedule of Test Results , These Schedules shall be based upon the models given in Appendix 6 of BS-7671 :
(2) the Schedule of Test Results shall Identify every Circuit , including its related protective ( 632.2 ) device(s) ,
And shall record the results of the Appropriate tests and measurements detailed in chapter 61 ,
(3) the Electrical Installation Certificate shall be compiled , signed / authenticated by ( 631.4 )
A competent person or persons stating that to the best of their knowledge and (632.3 )
Belief the Installation has been designed , constructed , Inspected and tested in accordance with BS-7671 , any permissible deviations being listed ,
(4) any defects or omissions revealed by the Inspector shall be made good and ( 632.4 ) Inspected and Tested again before the
Electrical Installation Certificate is issued :

Initial Inspection & Testing : GN-3

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 ,

Periodic Inspection : GN-3

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 and
Schedule of Test Results : should Accompany the Periodic Inspection Report :

Notes : on completion and guidance for recipients are provided with the form ,

Schedule of Test Results : GN-3 2391-10 / 2392-10 ,

The Client ,
Certificates & Reports GN-3
( 631.1.) Following the Initial Verification of a New Installation or Changes to an Existing Installation ,
( 632.1.) an Electrical Installation Certificate , together with a Schedule of Inspections and a Schedule of Test Results ,
Is Required to be given to the Person Ordering the Work . in this context , “ Work “ means the Installation work ,
Not the work of carrying out the Inspection ( 631.2 ) and Test , likewise , following the Periodic Inspection and Testing of an Existing Installation ,
( 634.1 ) a Periodic Inspection Report , together with a Schedule of Inspections and a Schedule of Test Results , is Required to be given to the Person Ordering the Inspection ,

Sometimes the person Ordering the Work is Not the User , in such cases it is Necessary for the User ( e.g. Employer or Householder )
To have a Copy of the Inspection and Test Documentation . it is Recommended that those Providing Documentation to the Person Ordering the Work Recommend that the Forms be Passed to the User Including any Purchaser of a Domestic Property :

Electrical Installation Certificate : GN-3

Regulation ( 631.1 of BS-7671 Requires that, Upon Completion of the Verification of a New Installation ,
Or Changes to an Existing Installation , an Electrical Installation Certificate based on the Model given in Appendix 6 of BS 7671 , shall be Provided , Section ( 632 ) Requires that :

(1) the Electrical Installation Certificate be Accompanied by a Schedule of Inspections ( 632.1 )
And a Schedule of Test Results , These Schedules shall be based upon the models given in Appendix 6 of BS-7671 :
(2) the Schedule of Test Results shall Identify every Circuit , including its related protective ( 632.2 ) device(s) ,
And shall record the results of the Appropriate tests and measurements detailed in chapter 61 ,
(3) the Electrical Installation Certificate shall be compiled , signed / authenticated by ( 631.4 )
A competent person or persons stating that to the best of their knowledge and (632.3 )
Belief the Installation has been designed , constructed , Inspected and tested in accordance with BS-7671 , any permissible deviations being listed ,
(4) any defects or omissions revealed by the Inspector shall be made good and ( 632.4 ) Inspected and Tested again before the
Electrical Installation Certificate is issued :

Initial Inspection & Testing : GN-3

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 ,

Periodic Inspection : GN-3

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 and
Schedule of Test Results : should Accompany the Periodic Inspection Report :

Notes : on completion and guidance for recipients are provided with the form ,

Requirements for Inspection & Testing : GN-3

General Procedure
( 134 ) Where Diagrams Charts or Tables are Not available , a Degree of Exploratory Work may
( 611.3 ( xvi ) be Necessary so that Inspection and Testing can be carried out safely and effectively. ( 514.9 ) A survey may be Necessary to indentify Switchgear , Controlgear and the Circuits they Control ,

Note : should be made of any known changes in environmental conditions , building structure , and alterations or additions
Which have affected the suitability of the wiring for its present load and method of installation ,

( 610.1 ) During the inspection , the opportunity should be taken to identify dangers which might
( 621.3 ) Arise during the testing , Any location and equipment for which safety precautions may be necessary should
Be noted and the appropriate step taken ,

Periodic tests should be made in such a way as to minimise disturbance of the installation and inconvenience to the user,
Where it is necessary to disconnect part or the whole of an installation in order to carry out a test , the disconnection should be
Made at a time agreed with the user and for the minimum period needed to carry out the test , Where more that one test necessitates a disconnection, where possible they should be made during one disconnection period ,

( 612.3.2 ) A careful check should be made of the type of equipment on site so that the necessary
( 612.3.3 ) precautions can be taken , where conditions require, to disconnect or Short-Out Electronic and other equipment
Which may be damaged by testing , Special care must be taken where control and protective devices contain electronic components ,

( 514.9 ) if the inspection ans testing cannot be carried out safely without diagrams or equivalent information , Section 6 of the Heath ans Safety at Work etc , Act 1974 can be interpreted to require their preparation .

 

[amberleaf]

16th / 17th

Edition Required local Supplementary Bonding be provided connecting together all exposed and extraneous conductive parts in the zones.
This is no longer required in this location provided the following conditions are met :
* All Final Circuits of the location comply with the Automatic Disconnection Requirements According to Regulation 411.3.2 :

* All Circuits are RCD protected in Accordance with 701.411.3.3

* All Extraneous-Conductive Parts of the location are Effectively Connected to the Protective Equipotential Bonding according to

regulation 411.3.1.2 ( Previously termed Main Equipotential Bonding :

-&- Ask you about Earthing / Protective Conductors , and all that look up Regs , p-32 ←←←←←←
16th Old Main Equipotential Bonding ↔ ( New 17th – Main Protective Bonding Conductor ) -&-
16th Old Supplementary Bonding ↔ ( New 17th – Supplementary Protective Bonding Conductor(s) where required : -&-

MINOR ELECTRICAL INSTALLATION WORS CERTIFICATE : GN-3 - 2392-10

Part 3 : Essential Tests :

The relevant Provisions of part 6 ( Inspection & 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 earthen terminal :
(2) Measure the insulation résistance 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 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 , also Regs , ( 633.1 )

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 .

Part 2 : Installation Details :
(2) The method of fault protection must be clearly indentified , e.g. Automatic Disconnection of Supply ( ADS )
(4) if the existing installation lacks either an effective means of earthing or adequate main equipotential bonding conductors,
This must be clearly stated see Regs , ( 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 ,

Isolation of Supply : GN-3

The Requirement of Regulation (14 ) of the Electricity at Work Regulations 1989 regarding working on or near live parts must be Observed during Inspection of an Installation ,

In Domestic type premises the whole Installation can be readily isolated for inspection ,
But with most other Installations it is Not-Practicable and too disruptive to isolate the whole Installation for the amount of time that is required for a comprehensive inspection , Much of the inspection in such premises has to be done whilst the Installation is in operation ,

Main switch panels can rarely be isolated from the supply for long periods; similarly, the disruption that may be caused by isolating final circuit distribution boards for long periods often cannot be tolerated ,

Distribution boards should be isolated separately for short periods for the internal inspection of live parts and examination of connections ,

Where it is necessary to inspect live parts inside equipment , the supply to the equipment must be disconnected ,

In order to minimise disruption to the operation of premises , the appropriate supplementary testing should be applied at the same time as the inspection ,

Accessories & Switchgear :
It is recommended that a random sample of accessories and switchgear is given a ( 611.3 ) (v)
Thorough internal visual inspection of accessible parts to assess their electrical and ( 611.3 ) (vi )
Mechanical condition , where the inspection reveals :

(1) results significantly different from results recorded previously
(2) results significantly different from results reasonably to be expected :
(3) adverse conditions , e.g. fluid ingress or worn or damaged mechanisms ,

The inspection should be extended to include every switching device associated with the installation under inspection unless there
Is clear evidence of how the damage occurred ,

Generally , it is not appropriate to apply sampling to socket-outlets and items of Class I equipment :

 

[amberleaf]

Direct Measurement of ( Zs ) :

Direct measurement of Earth-Fault Loop Impedance is Achieved by Using of an ( Earth-Fault Loop Impedance Tester )
( Instrument Designed Specifically for this Purpose ) Instrument Operates from the Mains and therefore can Only be Used on a Live Installation :

The Instrument is fitted with a Standard “ 13Amp Plug “ ( BS-1363 : Class I Equipment : BS-1362 : Cartridge Fuse : Regs: p-229 )
By Plugging the Instrument into a Suitable Socket-Outlet
Test Leads must Comply with GS-38 : Fused , 4mm / 2mm , for taking Measurement at other points on the Installation ,

In Order to Eliminate any Parallel Paths , 17th The Main Protective Bonding Conductors are Disconnected for the Duration of this Test ,
This will ensure that the reading is Not Distorted by the Presence of Gas or Water Service Pipes acting as part of the Earth return path ,
( Precautions Must be Taken , however , to Ensure that the Main Protective Bonding Conductors are Reconnected after Test ,

Earth-Fault Loop Impedance Testers are connected directly to the Circuit being tested and care must be taken to prevent danger ,
If a break had occurred anyway in the Protective conductor under test, then the whole of the earthing system could become live
It is essential therefore that Protective conductor continuity tests be carried Out Prior to the Testing of Earth-Fault Loop Impedance ,
( Communication with Other Users of the Building and the use of Warning Notices and barriers is essential ,

Measurement of ( Ze )

The value of ( Ze ) can be measured using an Earth Fault Loop Impedance Tester at the Origin of the Installation .
However , as this requires the removal of covers and exposure of live parts , Extreme care must be taken and the operation
must be supervised at all times, The Instrument is Connected Using Approved leads and probes between the Phase Terminal of the
supply and the means of Earthing with the Main switch Open or with all Sub-Circuits Isolated .
in order to remove the possibility of Parallel Paths, The means of Earthing must be Disconnected from Main Protective Bonding Conductors
for the Duration of the Test ,
with the Instrument correctly connected and the Test Button pressed , the Instrument will give a direct reading of the value of ( Ze )
Remember to Re-Connect all Earthing Connections on Completion of the test ,

Earth-Fault Loop Impedance :

When Designing an Installation , it is the Designers responsibility to ensure that , if a Phase-to-Earth Fault develop ,
The protection device will operate safely and within the time specified by BS-7671 :
Although the designer can calculate this in theory , it is not until the Installation is complete that the calculations can be checked ,

It is Necessary therefore to Determine the Earth-Fault Loop Impedance (Zs) at the Furthest Point in each Circuit and to Compare the Readings Obtained with Either the Designers Calculated Values or the Values Tabulated in BS-7671 :

The Earth Fault Loop is of the following Elements :

* The Phase Conductor from the Source of the Supply to the Point of the Fault :
* The Circuit Protective Conductor :
* The Main Earthing Terminal and Earthing Conductor :
* The Earth Return Path ( Dependent on the Nature of the Supply , TN-S , TN-C-S , etc :
* The Path through the Earthed Neutral of the Supply Transformer :
* The Secondary Winding of the Supply Transformer :

The Value of Earth-Fault Loop Impedance :
* Direct Measurement of ( Zs )
* Direct Measurement of ( Ze ) ( Ze ) at the Origin of the Circuit and Adding to this the value of ( R1 + R2 ) Measured during Continuity Tests , ( Zs = Ze + ( R1 + R2 )
* Obtaining the value of ( Ze ) from the Electricity Supplier and Adding to this the value of ( R1 + R2 ) as above ,
However , where the value of ( Ze ) is obtained from the Electricity Supplier and is not actually measured ,
A Test must be Carried out to Ensure that the Main Earthing Terminal is in Fact Connected to Earth Using an Earth Loop Impedance
Tester or an Approved Test Lamp :

Measurement by Standard Method : Method Using the Two ( Methods 1 / 2 ) 2392-10 / 2391-10 ,

The Test Requires the Use of Two-Temporary Test Spikes ( Electrodes )

E : = the Electrode in the Ground Under Test , ( C1 / P1 ) Link ,
C2 : = a Temporary Test Spike / Electrode ,
P2 : = a Temporary Test Spike / Electrode ,

> Test Method 2 : < GN-3 : ←←←←←

This is an Alternative Method : Earth Electrode for RCD ,
If the Electrode Under Test is being used in Conjunction with a Residual Current Device
The following Method of Test may be Applied as an Alternative to the Earth Electrode Résistance Test Described ,
In these Circumstances , Where the Electrical Résistances to Earth are relatively high and precision is Not-Required ,
An Earth Fault Loop Impedance Tester may be Used :

Earth Fault Loop Impedance Tester : GN-3 ←←←←←
These Instruments Operate by Circulating a Current from the Line Conductor into the Protective Earth ,
This will raise the potential of the protective Earth System ,

To Minimise Electric Shock Hazard from the potential of the protective conductor , the Test Duration should be within Safe Limits :
This means that the Instrument should Cut Off the Test Current after ( 40mS ) or a time Determined by the Safety Limits Derived
From the Information Contained within DD IEC/TS 60479-1 , if the Voltage Rise of the Protective Conductor Exceeds ( 50V ) during the Test ,

Test Method (1) 2392-10 : -&- I got this One , ←←←←← -&-
Before this Test is Undertaken , the Earthing Conductor to the Earth Electrode must be Disconnected Either at the Electrode or
At the Main Earthing Terminal , this will Ensure that all the Test Current Passes through the Earth Electrode Alone ,
However , as this will leave the Installation Unprotected against Earth Faults :

Switch Off the Supply Before ↔ Disconnecting the Earth , ←