***Useful Information for Apprentices***

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After Midnight . 2.05 minutes

• Which of the following is not classed as a legal document ( BS-7671 )
* perhaps the one we use most often .
• The correct British Standard identification number for a 6A type B miniature circuit breaker is ( BS-EN 60898 )
* The most common written on test sheets .
• The term reasonably practicable means ( Weighing a risk against the trouble . time & money needed to control it ) ◄ -&-s
* Should do everything we can . ◄◄◄
• BS-7671 Requirements for electrical installations sets out to protect ( Persons . property & livestock )
* Every Man . Woman . Cow & where they live . etc ….
• BS-7671 Guidance Note 3 covers ( Inspection & testing )
* A very useful one to have in the van .
• What other British Standard covers . earthing & lighting protection ( BS-6651 )
* you either know it or you don’t .
• The term system means !!!
* The start . middle & end .
- Any conductor in a system which is intended to carry electric current in normal conditions , or to be energised in normal conditions .
- Anything used . intended to be used or installed for use . to generate . provide . transmit . transform . control or use electrical energy .
- A conductor of electrical energy .
- An electrical system in which all the electrical equipment is . or may be . electrical connected to a common source . ●
• Which one of the following is covered by additional special regulations not in BS-7671 ( Storage of petroleum ) !! The big Bang Theory “
* The most dangerous .
• Which part of the Electricity of Work Regulations covers competency ( part 16 )
* What sort of hint , it’s part 16 .
• The Electricity at Work Regulations states with regards to working on live conductors ( Should be avoided in all circumstances’ unless otherwise unavoidable )
* We shouldn’t and we know it . but sometimes .
• BS-7671 is divided into how many parts ( 7 parts )
* 7 main parts .
• Which part of the Electricity at Work Regulations covers Earthing ( part 8 )
* What sort of hint . it’s part 8
• if an item of equipment conforms to BS-EN standards it means ( it conforms to European standards )
* EN is short for .
• What other British Standard covers Fire detection & Fire alarm systems ( BS-5839 )
• Which one of the following is covered by additional special regulations ( lightning protection )
* BS-6651 covers the installation as well .
• BS-7671 The IEE wiring regulations covers al of the following except one that has additional regulations ( lightning protection )
* BS-6651 covers this type of installation .
• Which of the following is classified as a legal document ( the Electricity at Work Regulations )
* The big electrical document issued by the Government .
• Which part of the Electricity at Work Regulations covers the installation & protection of conductors ( )
* Part 7 .
• Emergency lighting is covered by BS-7671 and what other BS regulation ( )
* BS 5266 .
s/20

 

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After Midnight . 2.05 minutes (2)

• The regulations define Extra Low Voltage as ( 50V a.c. )
* Not quite that low but still .
• Guidance on the correct selection . use & inspection & testing of electrical installations can be found in ( BS-7671 )
* Part 6 .
• The statutory regulations that cover people working on electrical installations are ( the Electricity at Work Regulations )
* To much .
• The term absolute means ( Must be met regardless of cost )
* Absolutely absolutely .
• BS-7671 IEE Wiring Regulations apply to ( Electrical contracting )
* What do we do every day .
• The BS number for standard 13A socket outlet system is ( BS 1363 )
* Not the breakers or plug top fuses .
• Additional information when working with large motors can be taken from ( Manufacturers data charts )
* Some produce a lot of additional useful information .
• The correct table showing maximum fixing & clipping distance can be found ( The O/S/G.)
• A wiring diagram shows ( The actual connection of conductors )
* how things connect together perhaps .
• When preparing a quotation for an installation . the best item to use are ( Layout drawings and take off sheets )
* What and where .
• One method of ensuring that site drawings are easy to interpret to interpret by all parties is by using ( BS-EN 60617 symbols )
* The defacto symbols standards .
• The progress of an installation can be best monitored by ( Work & time sheets )
* What’s happened and when .
• When items are delivered to site . they should be checked against the ( Delivery note )
* Obvious one . clues in the question .
• Progress on a large electrical installation can be best organised by ( Bar chart )
* One to the next to the next ……. Pint !!
• An exploded view diagram from manufacturers shows ( Complex components split apart )
* if it’s hard to understand .
• Symbols used in electrical installation design can conform to ( BS-EN 60617 )
* The European Standard .
• When preparing to begin an installation . a list of materials will be drawn from the ( Drawings & specification )
* Count and check .
• On completion and handover of an installation . the client should receive ( An operations manual )
* So that the installation can be used .
• Which of the following information is not provided on a layout drawing ( Cost of the installation )
* Where . what . how big but not .
• In situ measurements can be taken ( By measuring quantities on site )
* In situ means in Place .
• Complex electrical systems may be better understood by referring to ( Manufacturers manuals )
* They may contain useful extra information .
• Day work is ( Additional work carried out outside of the main contract )
* Extra .
• Which of the following is necessary for an electrician to install equipment on a construction site ( Drawings & diagrams )
* Where and what do we install .
• What documents lays out in detail the requirements of an electrical installation before it starts ( Specification )
* Big written document with loads of information .
• At the end of a working week . an electrical operative should complete a ( Time Sheet )
* Allows costs to be forwarded to a job .

How’s about Big thanks You.s Amber.

 

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After Midnight . 2.05 minutes (3)

• An RCD installed as additional protection for socket outlets should be rated at ( 30mA )
* Touched voltage applies here .
• Large armoured cables are most suitably installed in ( Ladder racking installations )
* Big special type of tray .
• The interior of a bathtub is classified as ( Zone O )
* Nothing )
• An earthing system called TN-C-S is also known as ( A PME system )
* More than one Earthing point .
• Contactors are commonly used on ( Motor control circuits )
* Think of direct online starter .
• Socket outlets on a construction site not protected by SELV should have additional protection via a ( RCD )
* How do we add protection to a circuit that is already protected by an MCB .
• Simple control of a central heating system be achieved by using a ( Thermostat )
* A lot of houses have these for their systems .
• Main factors that would influence the choice of wiring systems are ( Ambient temperature and Mechanical damage )
* Environment and external influences .
• A simple wall mounted room thermostat operates by using a ( Bi – metallic strip )
* A piece of metal that bends when it gets warm
• if the calculated voltage drop at the load was unacceptable . what is one action you can take ( )
* Less résistance .
* Increase live conductor sizes . ••••
* Increase the voltage at the supply .
* Increase earthing conductor size .
* Decrease CPC size .
• Underfloor pressure pads are commonly used in ( Security systems ) “ “Not underfloor Heating “ ”
* When people step in places they should,t be .
• One advantage of proprietary cables such as FP200 compared to MIMS is ( Quicker to install )
* No better protection but no specialism required .
• If an electrical circuit supplies equipment outside the Equipotential Zone a ( RCD must protect the circuit )
* Think of what protects us outside the Equipotential Zone .
• Which earthing system can use the outer sheath as an incoming earth ( TN-S )
* Both separate .
• Magnetic door contacts placed at the top or bottom of door frames are used in ( Security systems )
* When a door is opened that should,t be .
• A 4mm2 conductor has a design current of 20A and a length of 20 meter. If the voltage drop is 11mV/A/m what is the voltage drop at the terminals’ ( 4.4V )
* Remember the formula mV/A/m x Ib x I divided by 1000 .
• A radial circuit is protected by a 30A semi enclosed fuse . what is the tabulated current carrying capacity of the cable supplying the circuit assuming no other correction factors apply ( 41.4A )
* Remember . it’s protected by a BS-3036 fuse .
• PVC conduit should be avoided outdoors because ( UV rays can damage the construction )
* The sun is very damaging .
• In a high moisture environment . what would be the preferred choice of wiring system ( PVC/PVC cable in trunking )
* Remember . conducting & corrosion .
• A component designed to operate an item of electrical equipment under normal conditions is known as ( A switch )
* We use one every day .
• Installations that require minimal disturbance of building fabric are best installed in ( Bare MIMS cable )
* some jobs specify this . especially rewires of old properties .
• The purpose of a protective device at the origin of the circuit . ( Protects the circuit conductors and cable ) ◄
* Doesn’t necessarily protect us .
• What supply system uses the neutral conductor as an Earth ( TN-C-S )
* PEN or PME .
• A lighting circuit is controlled by two 2-Ways and Intermediate switches . this is known as ( Functional switching ) ◄
* Everyday type of switching .
• An Edison screw lampholder should have its centre pin connected to the ( Line conductor )
* it’s the part that makes it Glow .
• An increase in the ambient temperature will result in ( Decrease in the current carrying capacity of a conductor )
* The higher the heat . the lower the current capacity .
• The installation of fibre optics and Cat 5e cables requires ( Specialist knowledge & Training )
* Do you know what you are doing .
• A 1.5mm2 conductor has a design current of 4A and a length of 10 meters . if the voltage drop is 29mV/A/m what is the voltage drop at the terminals ( 1.16V )
* Remember the formula mV/A/m x Ib x I divided by 1000 .
• The IEE regulations advise that construction site should be tested ( Every three months )
* Quite frequently .
• Three fluorescent fittings rated at 60W each will draw how much current ( 1.4A )
* Don’t forget the discharge part of things .
• When installing PVC conduit in areas of fluctuating temperatures ( Expansion joints should be used )
* What happens when things get hot and cold .
• Maintained emergency lighting ( is switched as a normal part of a circuit and lights in the event of power failure ) ◄
* Those little Red LED fittings you see dotted about .
• A 10kW shower in a normal domestic situation will draw how much current ( 43.5A )
* The good old power formula .
• Isolators are designed to operate under ( No load conditions ) ◄
* Not when they are on .
• An earth fault current will flow in a installation when ( A line conductor comes into contact with an exposed conductive part )
* The earth fault loop path
• The type of control system used in conjunction with heating & ventilation systems is known as ( Environmental control )
* it’s all around us .

 

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Assessment of general characteristics’ " Lerning curve "

• Fault protection protects against ( Electric shock under fault free conditions )
* Not necessarily in contact with an electrical system .
● ( Fault Protection : p/24 ) Protection against electric shock under single-fault conditions :::::::::::::: 17th Ed .

• Current carrying capacity is defined as ( The maximum amount of current carried by a conductor under specified conditions )
* The amount of current .

• A neutral can be defined as a ( Live conductor ) ◄◄
* is it protective ? . is it a live .

• An example of a Band 1 circuit might be ( A telephone cable installed in a domestic property )
* is it protective ? is it a Line ? ( With Telephone Line !! does not Mean Line/Live conductor as in Power 230V ) p/31

• A circuit protective conductor is ( A protective conductor providing a connection between exposed parts and the main earth terminal )
* CPC is commonly called earth but what part of earth .

• SELV denotes an extra low voltage system that is ( Electrically separated from the general mass of earth )
* What does the S stand for .

• A bonding conductor is ( A protective conductor providing Equipotential bonding )
* Connects to the services ………….. Etc.

• A final circuit is defined as the wiring between the ( Distribution board 2391 / 2392-10 . Consumer Unit and current using equipment )
* Final as in …. Last bit.

• An earth conductor is ( A protective conductor connecting the main earthing terminal of an installation to an earth electrode or other mean of earthing .
* The main baby .

• A double insulated hand held electric drilling machine is known as ( Class 11 equipment )
* Think about where you see the symbol .

• An example of a Band 11 circuit might be ( take you best shot ?? Ring ) p/31
* is it protective ? is it a Line ?

• The following are all reasons for dividing a circuit except ( Allow for future expansion within the electrical installation )
* One requires more than just room in an installation .

• Which of the following is considered an external influence according to part 5 ( Ambient temperature )
* Usual influence .

• Every installation shall be divided into circuits to ( Reduce electromagnetic interference )
* Stop the influence within circuits .

• Which of the following forms part of the assessment of general characteristics ( Maintainability )
* Look in part 3 .

• Any overcurrent protective device installed at the Origin of a circuit must have a breaking capacity of ( Equivalent or more to the prospective short circuit current ) ◄◄
* What causes the maximum current to flow under fault conditions .

• Correct coordination between conductors and overcurrent protection device is achieved when ( In is not less than Ib ) ◄◄
* Do you want the breaker to trip when full load is applied .

• Which of the following forms part of the assessment of general characteristics ( External influences )
* Look at pat 3 .

• When classifying an area for external influences . the code given to an are that had a high ambient temperature would be ( AA )
* Appendix 5 .

• it is recommended when calculating the demand for discharge lamps a multiplying factor should be applied . what is the factor ( 1.8 ) ◄◄
* it takes into account starting currents .

• An overload current could arise when ( Excessive mechanical load is applied to an electric motor .)
* Overload occurs in normally healthy circuits .

• Installation should be arranged so as to avoid danger in the event of a fault . and to facilitate safe operation . inspection . testing & maintenance . one method of complying with this is to ( Divide the installation into Band of circuits )

• Which of the following is not considered an external influence according to part 5 ( Machinery & Plant )
* An external influence not from human origin .

• Which of the following does not fall under compatibility ( Unbalanced loads ) (iii)
* Look up 331 .

 

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After Midnight . 2.05 minutes (4)

• MIMS cable clipped direct to the structure of the building is most effectively fixed using ( P clips )
* All round clips for integrity .
• When installing metal trunking system ( Earth continuity tags must be used )
* Don’t forget that metal conduits to .
• The prevention of electric shock on a construction site can be most effectively reduced by ( Using a battery tool )
* Totally separated from electric source .
• Minimum bending radii for conduit is necessary to ( Ease drawing in reduce stress on conductors )
* So it doesn’t squeeze the cables at one point
• The most accurate method of installing very short vertical SWA cable runs is using a ( Plumb bob )
* Simple old fashioned device .
• Forming 90° bends in steel conduit can be more accurately achieved by using ( A bending machine )
* Present tool .
• The first test to be carried out on a completed lighting circuit is ( Continuity CPC )
* The most important one .
• The most accurate method of installing long horizontal conduit runs is using a ( Laser level )
* Set it up and follow the dots .
• Lengths of SWA installed in a large warehouse can be best fixed using ( Girder clips )
* A large warehouse is unlikely to have a ceiling .
• During the installation stage , conduit should be deburred with a ( Reamer )
* Sometimes also called deburrer .
• When using the R1 + R2 method for determining continuity of CPC . we can commonly also perform the ( Polarity )
* Does it work correctly .
• The most suitable fixing device for conduit to be embedded into the structure is ( Crampets )
* Cheap but effective method .
• A lighting circuit has had it’s continuity of CPC tested using the wander lead method . how is this ( R2 )
* Like the star wars Robert . but without the D2 but …………
• After completion of work on a construction site . you should ( Leave the site clean & tidy & store materials & tools in a safe . secure place )
* Safe & secure .
• The most common fixing method for clipping SWA direct is ( Cleats )
* Like clips for armoured .
• Before and during the carrying out of an insulation résistance test . it is necessary to ( Just some off )
- Operate any two way & intermediate switches in lighting circuits .
- Remove lamps from lighting circuits .
* A few things to remember .
• When manufacturing a 90° bend in steel trunking . the most effective tools for making the trunking are a ( Tri square with set 45° angle & scribe )
* A 90° bend is fabricated by splitting the angle in two .
• After performing a lamp change on an installation what should you do with the old lamps ( Return them to a suitable disposal facility )
* Ready for moving on .
• Any left over waste materials on a construction site must ( Be stored in suitable containers of site )
* Ready for moving in .
• Space factors are recommended by BS-7671 to ( Allow dissipation of conductor heat )
* A lot of cables can generate a lot of .
• When fixing large switchgear to concrete walls . the most effective devices are ( Masonry bolts )
* The big bolts .
• The most common fixing method for surface fixing to plasterboard is ( Spiral fixings )
* Windy fixings make their own hole .
• The most common fixing method for conduit systems are ( Spacer bar saddles )
* Standard saddles .
• Why is it necessary to perform a continuity of CPC test on a completed circuit before all the other tests ( Each subsequent test relies on the integrity of the CPC ) ◄◄
* What are the next tests . will they work properly .
• An insulation résistance test is necessary to ( Confirm the integrity of the insulation )
* Check the résistance of the insulation perhaps .
• The most effective tool for removing burrs within trunking is ( A file / Deburrer )
* A good old fashioned tool used for metal .
• Before beginning work on an electrical circuit ( It should be isolated and locked off ) ◄◄
* Safety first always .
• If a hole is to be made in the building fabric to allow trunking to pass through ( Suitable arrangements should be made to prevent the spread of Fire ) ◄◄
* Don’t let it spread .
• Any portable equipment used on a construction site should ( Be checked before & after use for damage )
* Safety first always .
• A fuse protecting the plug top . must conforms to ( BS-1362 )
* The only plug top one there is .
• Conduit runs should have boxes installed regularly to ( Enable easier drawing in of cables )
* Don’t drag them through too far .

• The most accurate tool to mark steel trunking for cutting is ( A Scribe )
* Get the most thinnest line to follow you’ll be aright .
• When installing electrical equipment in the basement of an industrial installation . what should we take into account .( Rodent damage )
* What can cause a lot of damage .
• Steel conduit used for lighting runs is to be connected to trunking for the longer runs . what is the best method of terminating the conduit into the trunking ( Brass bush & coupler )
* Typical method .
• A stop button is used to protect a motor circuit . what is important about this type of circuit ( It must be impossible to re energise unintentionally )
* Reset the button . what don’t we want to happen .
• Distance saddles might be used in area ( of high condensation )
* They move the conduit further off the wall .

 

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201-2

• Which of the following would not involve electrotechnical activities ( Automotive wiring companies )
* They are specifically left out of the regs :
• Reference to maintained and non-maintained systems are made ( Emergency lighting installations )
* Some come on normally . others in mains failure .
• What system can control heating and ventilation a construction via a series of sensors . ( Building management system )
* Looks after the whole ………
• A tender to apply to undertake work is normally completed by the ( Estimator )
• A component installed to detect increases in temperature is known as a ( Heat detector )
* Remember there are 2 distinct types .
• Category 6E cabling used in transmission of ( Data )
* Transmits signals .
• A standard ring final socket outlet system is known as a ( Power installation )
* Transmits electricity for general use .
• The jointing of high voltage cables is usually used in ( Distribution networks )
* Moving electricity from one building to another .
• High voltage cable jointing is usually carried out by ( Regional electricity companies )
* Supply companies .
• The industry body that represents employers in electrical contracting is the ( ECA )
* Electrical contracting ……….
• A foreman ( Runs the day to day operations on a construction site )
* Should be making sure you do your job correctly .
• Fibre optic cabling is used in transmission of ( Data )
* Transmits signals via light .
• A system installed to detect the presence of unwanted personnel is known as a ( Security installation )
* Sometimes called burglar alarms .
• The industry body that represents and negotiates on behalf of employees in the electrical contracting industry is the ( JIB )
* Sort out your wages rates .
• A series of pumps and machinery are to be linked together to perform various duties towards the same outcome . this would be known as a ( Control system )
* Everything is ---------- by a single system .
• An estimator is responsible for ( Pricing a potential installation )
* Estimating how much .
• A large industrial panel feeding a large factory has several components installed to monitor voltage . current & power consumption . this is known as . ( Instrumentation )
* Items used to measure thing are called ………..
• A system installed to detect flames or smoke is known as a ( Fire alarm installation )
* easy one here .
• A contracts manager ( Oversees an installation build from start to finish )
* Quite high up in the chain .
• A high voltage supply is normally installed by ( The regional supply authority . )
* Transmission * distribution .

 

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Inspection & Testing – 6

• A polarity test is conducted to verify that ( Every fuse and single pole device is connected in the line conductor only )
* Things work and are protected
• When installing 3-Phase equipment . what additional test should be carried out ( Phase sequence test )
* Maybe the motor spins the wrong way .
• A legible chart . diagram or table relating to the installation should provide information relating to ( The identification of circuit protection )
* Can easily locate the …… in event of fault . maintenance etc .
• An earth fault loop impedance test performed on a ring final circuit will record ( The résistance of the line conductor . protective conductor & external loop impedance )
* Kit . bang . Kaboodle .
• The minimum value of insulation résistance test performed on a PELV installation is ( 0.5MΩ )
* Look up part 6 . SELV –PELV : 250V d.c. ≥ 0.5MΩ . Table 61 .
• An electrical installation certificate must indicate responsibility for the installations ( Design . construction . inspection & testing )
* Start . middle & end perhaps .
• A polarity test should be carried out ( Before the installation is energised )
* Pre or post is the question . or maybe dead or live ?
• The minimum value of insulation résistance test performed on 230V a.c. installation is ( part 6 )
* Look up part 6 . Table 61 . 500V d.c. ≥ 0.1MΩ .
• A minor works certificate should be issued where ( An alteration not requiring an additional circuit needed . )
* Small works .
• An insulation résistance test performed on a PELV installation should be capable of producing a test voltage ( 250V d.c. )
* Part 6 .
• An electrical installation certificate should be signed by ( A competent person )
* Know what you’re doing do we Sis .
• An insulation résistance test is conducted to verify that ( There is no breakdown of the conductor insulation )
* Pretty obvious .
• Before conducting an insulation résistance test you should ( Ensure that all voltage sensitive devices are taken are disconnected )
* Think about the voltage you are putting through .
• A periodic inspection report would be carried out on ( An existing property ) this Q) would be asked by -&-s 2392-10 .
* Over a period of time .
• Four of the tests on a completed installation required by BS-7671 are ( 2 . 3 . 1 . 4 )
1) Insulation résistance .
2) Continuity of protective conductors’ .
3) Continuity of ring final circuits .
4) Polarity .
Which of the following shows the correct sequence of these tests .
* Think about the sequence and what needs to come first .
• An insulation résistance test performed on a 50V a.c. SELV installation should be capable of ( 250Vd.c. )
* Look up part 6 .
• The frequency of a periodic inspection report on an older installation depends upon ( The type . use & operation of the installation )
* A rarely used building or a frequently used.
• The minimum value of insulation résistance test performed on a SELV installation is ( 0.5MΩ )
* Look up part 6 .
• Which one of the following items is included in the checklist during the initial verification of an ( Presence of diagrams & instructions )
* Something to help find your way around .
• Before conducting an insulation résistance test you should ( Ensure that all lamps are removed )
* What might confuse the readings .
• No alteration . temporary or permanent . shall be made to an existing installation unless the ( The existing equipment is adequate for an additional load )
• A test of continuity at each socket outlet of a ring final circuit is carried out to ensure that ( That the Ring is not Interconnected )
* What are the associated dangers .

 

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Unit 2 :
Inspection & Testing & Commissioning .

1) List three widely used types of : ( it’s the Meaning of the Word -&-s always get’s you On )
a) Wiring system .
b) Wring enclosure .

Solution :- ( any 3 )
a) Micc cable .
PVC/SWA cable .
XLPE/SWA cable .
PVC twin & earth cable .
Fire retardant cable .

b) PVC trunking . ( any 3 )
Steel trunking .
PVC conduit .
Steel conduit .
Ducting .

2) When making an Area Safe to Work in :
a) List three Procedures to be taken before commencing work .
b) Describe the permit to work procedure .

Solution :-
a) Use barriers & tapes to cordon off an area .
Place warning signs in appropriate positions .
Isolate equipment from the supply .

b) The permit to work is a formal procedure in the form of written authorisation used to control work in potentially hazardous areas .

3) When carrying out large contracts .
a) List three parties likely to be concerned .
b) State the purpose of a site record .

Solution :-
a) Client .
Contractor .
Supplier .
Consultant .
Sub-contractor . ( any 3 )

b) Provides a continuous . updated record of all activities on site .

4) Describe the use of the following in monitoring the progress of a contract .
a) a Bar chart .
b) a Site diary .
c) Variation orders .

Solution :-
a) To display progress of different parts of a contract graphically .
b) A daily record of events on site .
c) Variation orders are requests for extra work or change to a contract and must be given in writing . the issue of variation orders may affect the main contract progress .

5) With reference to the application and use of residual current devices ( RCD )
a) list three situations where RCD protection is required .
b) State the primary function of an RCD .
c) Describe the term nuisance tripping . **

Solution :-
a) For sockets installed on TT earthing systems . For sockets outlets likely to supply portable equipment used out doors .
where satisfactory values of ( Zs ) cannot be achieved .
b) To limit the severity of electric shock .
c) When tripping occurs due to small leakage currents that do not constitute a real fault . **

 

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Learning Curve Only

Q ) Which is the preferred method of Protection on the D.C. side of a Photovoltaic Power Supply . ?????? ( PV ) 17th Ed .

1) Class 11 or Equivalent Insulation. ( Take your best Shot )
2) Placing Out of Reach .
3) Non-conducting location .
4) Earth free local Equipotential Bonding .

( p/200 – 712.412. )
17th Ed . Protection by the Use of Class 11 or Equivalent Insulation shall preferably be Adopted on the ( D.C.) Side .
PS. This is the Only Book that gives you the Answer’s to your Qs .

This is Just to make you aware of the Q/As that -&-s will as you one day . Amber. ( what is a Motor/Caravan – Touring/Caravan ) it’s the Wording .
p/209 - PS . Electrical Installations in Caravans & Motor Caravans .

Q) The Maximum Interval between Periodic Inspection of a Touring Caravan is ??????
At this time your Scratching your Head . !! ( Fig . 721 – p/211 – Bottom of / Periodic Inspection
Preferably not less than Once Every Three Years . & Annually if the Caravan is Used Frequently ………… etc .

 

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Q ) Regional Electricity Companies are Reluctant to Provide which of the Following to Construction Sites .??

a ) PME Supply . 704.411.3.1.
p/181 : A TN-C-S system shall Not be Used for the Supply to Construction Sites . Except for the Supply to a Fixed Building of the Construction Sites .
( PME : Protective Multiple Earthing )

1) The ( ESQCR ) Prohibit the use of a TN-C-S system for the Supply to a Caravan or Similar Construction .
2) Not Allowed in Certain Location’s i.e. Petrol Station’s .

b) TT Earthing System .
c) Single Phase Supply .
d) Three Phase Supply .

( PME ) Important to Ensure that the Neutral is Kept at Earth Potential by Earthing it at Many Points Along it’s Length / Hence “ Multiple Earthing “

An RCD that is Installed for Protection Against the Risk of Fire must be ?? -&-s
p/113 – 532.1 .
* The RCD shall be Installed at the Origin of the Circuit to be Protected .
Origin of an Installation . p/27
* The Position at which Electrical Energy is Delivered to an Electrical Installation .

 

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During a Test on an Installation . the Following Readings were Obtained : -&-s
( 20MΩ . 8kA . 22mS )
List the Instruments which gave these Readings . ??

i) Insulation Résistance 20MΩ .
ii) Prospective Short Circuit Current Tester . 8kA ( PSSC )
iii) RCD Tester . 22mS

One would use a Multimeter . 17th Edition . Nowadys

 

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Learning Curve :-

Q) The Test for the Continuity of CPC in a Radial Circuit feeding One Socket Outlet uses a Temporary Link and a Milli-Ohm meter .State !!
i) Where the Temporary Link is Connected .
ii) Where the Milli-Ohmmeter is Connected .
iii) What the Meter Readings Represents .

1) Between ( L ) & ( E ) at the Consumer Unit .
2) Between ( L ) & ( E ) at the Socket Outlet .
3) This Value is ( R1 + R2 ) for the Circuit..

Q) The Following Readings were Obtained during the Initial Tests on a Healthy Ring Final Circuit .
L1 – L2 / 0.8Ω : N1 – N2 /0.8Ω : CPC 1 – CPC -2 / 0.8Ω

a) What Readings would you Expect :-
i) Between L & N Conductors at each Socket Outlet ?
ii) Between L & CPC at each Socket Outlet ?
iii) What the L to CPC Reading Represents ?

● 0.4Ω
● 0.4Ω
● ( R1 + R2 ) for the Ring

 

[amberleaf]

The Relationship between the Primary & Secondary Voltages
( and the Number of Turns in the Coil )

Primary ( Input ) Voltage = Number of Turns Primary Coils . ( 230V ~ 2000 Turns )
Secondary ( Output ) Voltage = Number of Turns Secondary Coils . ( 100 Turns ~ Output Voltage )
So Output Voltage = Input Voltage x Number of Turns in Secondary in Secondary Coil :-
Number of Turns in Primary Coil .

Vs = 230V x 100T ÷ 2000T = 11.5V

In Symbols : Vp/Vs = Np/Ns & Vs = Vp x Ns /Np .

Learning Curve :
* Power Station Alternators Generate A.C. at a Voltage of 25kV.
Can Produce a Current of Up to 20kA .

The Power Generated by an Alternator can be Calculated From :-
P = I x V . ( 20000A x 25000V = 500000000W ) = 500MW

* if an Alternator has an Output of 500MW at 25kV . & the Voltage is Stepped up to 400kV . the Current will Be :-
I = P/V ( = 500000000W ÷ 400000V = 1250A = 1.25kA )

 

[amberleaf]

Alternating Current :

Alternating Current ( a.c. ) is a flow of electrons . which rises to a maximum value in one direction and then falls back to Zero before repeating the process in the opposite direction . in other words . the electrons within the conductor do not drift : flow : in one direction . but actually move backwards & forwards

The journey taken . i.e. starting at Zero . flowing in both directions and then returning to Zero . is called a Cycle . the number of Cycles that occur every second is said to be the Frequency and this is measured in Hertz ( Hz )

* Impedance : Total Opposition to Flow of a.c. in a Circuit . Combining “ Résistance . Inductance “ and “ Capacitance “ Measured in Ohms ( Ω ) Symbol ( Z )
* Inductance : Opposition created by a Changing “ Current “ in a Magnetic Field which induces a “ Voltage “ to Oppose Change in Current . either within a Circuit ( Self- Inductance ) or a Neighbouring Circuit in the same Magnetic Field ( Mutual Inductance ) Measured in Henrys ( H ) symbol L
* Inductive Circuit or Load : Containing Components with Windings . e.g. Motor . Generator or Transformer . which have Inductance .
* Inductive Reactance : Opposition to Flow of a.c. Produced by an Inductor . Measured in Ohms ( Ω ) Symbol XL
* Inductor : Component Introduced into a Circuit to Provide Required amount of Inductance .
* Hypotenuse : Side un a Right-Angle Triangle Opposite to the Right Angle ( Also . Sine . Cosine . Pythagoras “ Theorem )
* True or Active Power : Power Consumed by a Resistor , Dissipated as Heat and Not Returned to the Source ( also . Apparent Power . Reactive Power )

* Phase Voltage : “ Voltage “ Measured across a Single Component in a Three Phase Source or Load .
* Line Voltage : “ Potential Difference “ between any Two-Phase Conductor’s between Source and Load in a Three-Phase Electrical Circuit .

 

[amberleaf]

The AM 2 or Achievement Measurement 2 is a Completely External & Independent Assessment of Abilities to Complete an Apprenticeship .

Special Installation or Locations : 17th Editon .

• The maximum length of an extension cord used on a caravan site to connect to socket outlets should be ( 25m ) Fig 708 – p/192 NOTE:
( The Wording “ connect to socket outlets . 721.55.2.6. (ii) p190 / Caravan site wiring Only )
* Part 7 .
• Zone 1 in the bathroom is the ( Area directly above the bath or shower up to 2.25m above finished floor level ) 701.32.3 (i)
* Not quite the extreme end .
• External influences when designing an installation for a marina would include ( Contact of the body with earth potential )
( External influences : 709.512.2.)
i) Presences of water .
ii) Reduction in body résistance . •
iii) Contact of the body with earth potential •
* if the mass of earth is considered ( 0V ) then the sea must also .

• Photovoltaic equipment should always ( Be considered to be energised on the d.c. side ) Section 712 .
* Let there be light …. All the time .
• In agricultural situations . self supported suspension cables should be ( At a height of at least 6m ) 705.522 . (iii)
* Part 7 .
• What is the minimum protection afforded electrical equipment if installed on a Jetty in a marina ( IPX4 ) 709.512.2.1.1. Minimum !! IPX4/IPX5/IPX6.
Water Splashes ( AD4 ) [ Watch the wording !! JettyWharf , Pier . Pontoon . ( the most use IP Rating is IPX4/IPX2 .17th Edition )
* Part 7 .
• Underground distribution cables installed/buried in caravan parks that run under pitches or where pegs may be placed should be installed at a minimum depth of ( At a depth of 0.6m with Additional Mechanical Protection ) 708.521.1.1.
* Part7 .
• Amusement parks & fairground premises should use RCDs to protect all the following except ( SELV circuit . Hint 740.415.1. Additional Protection RCDs )
* Some things just don’t have an earth you know

(T) Inspection & Testing : 740.6. ( Learning Curve )
The Electrical Installation between its Origin & any Electrical Equipment shall be Inspected & Tested after each Assembly on Site .
Note : Internal electrical wiring of roller coasters . electric dodgems & similar equipment are not considered as part of the Verification .
Note : In special cases the number of the Tests may be Modified according to the Type of Temporary electrical installation .

Useful Junk : Amusement Parks & Fairground Premises
The Electricity at Work Regulations 1989 : Design Erection & Verification Electrical Installation in Fairgrounds . YES.

• The specified IP rating for areas with Zone 2 within a bathroom is ( IPX4 . 701.512.2.) In Zone 1 & Zone 2 : IPX4 )
* Not as extreme as Zone 1 or the same .
• A mobile unit should have a connection between the ( Vehicle Chassis & main protective bonding terminal ) 717.411.3.1.2.
* General mass of vehicle .
• Heating units designed to be use underfloor should have a minimum IP rating of ( IPX7 ) 753.512.2.5.
* Specially waterproof .
• Ceiling heating systems temperature shall not exceed ( 80°C )
* Specific section of the Regulations .

( 753.423 Protection against Burns )
In floor areas where contact with Skin or Footwear is possible , [Restricted] the surface temperature of the floor shall be limited ( for Example 35°C )
PS. This is Important – for [Part–P] etc.
753.424.1.1. To avoid the overheating of floor or Ceiling heating systems in buildings . one or more of the following measures shall be applied within the Zone where heating units installed to limit the Temperature to a Maximum of ( 80°C )

• In agricultural premises . final circuits Not Exceeding 32A should be protected by ( 705.411.1. (i) – 30mA – 40mS )
* The usual .
( Watch the Wording on this : (i) Not Exceeding (ii) More Than ) trip up One -&-s
• Electrical equipment installed in Zone O in a swimming Pools should be rated at ( External Influences /Electrical Equipment : IPX8 ) 702.512.2.
* Extreme . ( The Wording - Swimming Baths / Swimming Pools )
• A socket outlet or plug on a mobile vehicle installation should ( 717.55.1. Plugs& Connectors . BS-EN 60309-2 ) p/205
* Industrial . all the way !!
• Socket outlets supplying caravan pitches should be ( To BS-EN 60309-2 & IPX4 in accordance with BS-EN 60529 ) 708.553.1.8. p/191
* Industrial types .
• In a room containing a sauna , what additional protection is required ( RCD )
* The Godfather of additional protection .

This One is a Good Learning Curve : 703.411.3.3.
Additional protection shall be provided for all circuits of the Sauna , by the use of one or more RCDs having the characteristics specified in Regulation 415.1.1. RCD protection need NOT BE PROVIDED for the Sauna Heater unless such protection is Recommended by the Manufacturer , ◄◄

 

[amberleaf]

17th Edition :
Phase Conductor : see Line Conductor .!
Line Conductor : A Conductor of an a.c. system for the Transmission of Electrical Energy Other than a Neutral Conductor . A Protective Conductor or a PEN Conductor . The Term also means the Equivalent Conductor of a d.c. System unless Otherwise Specified in the Regulations .

( a PEN Conductor Combines both Protective Earth & Neutral Functions )

On a Low Voltage Domestic Supply to a House you get a Line which is alive and a Neutral which is the Return Wire .
Neutral Conductor : Live Conductor .

~ All Conductors Except the Circuit Protective Conductor are Classed as Live Conductors . in Practice the Neutral is Very near to Earth Potential & therefore sometimes Thought of as Not a Live Conductor . [ Wrong ]
( But if there is a Fault in the Circuit the Neutral can become Live as can Earth ) [ Current Flowing through a Résistance = Voltage ]

 

[amberleaf]

mA [ Milliamp = One thousandth of an Amp ]
km [ Kilometre = One thousand metres ]
µv [ Microvolt = One millionth of a volt ]
GW [ Gigawatt = One thousand million Watts .
kW [ Kilowatt = One thousand Watts ]

Alternating Current Circuit Calculations :
In D.C. Circuit is Limited by Résistance .
In A.C. Circuit’s the Current is Limited by Impedance ( Z ) Résistance & Impedance are Measured in Ohms .

For this Calculation . Ohms Law is Used and ( Z ) is Substituted for ( R )
( U/Z = I or Voltage ( U ) ÷ Impedance [ Ohms ]
= Current [ Amperes ]

• The Voltage Applied to a Circuit with an Impedance of 6Ω . is 200 Volts . Calculate the Current in the Circuit ?
[ U/Z = I ] 200 ÷ 6 = 33.33A .
• The Current in a 230V Single Phase Motor is 7.6A . Calculate the Impedance of the Circuit ?
[ U/I = Z ] 230 ÷ 7.6 = 30.26Ω
• A Discharge Lamp has an Impedance of 265Ω and the Current Drawn by the Lamp is 0.4A . Calculate the Voltage ?
[ Z/I =U ] 265 x 0.4 = 106 Volts .
• The Current through an Impedance of 32Ω is 8A . Calculate the Voltage Drop across the Impedance ?
[ U = I x Z ] = 8 x 32 = 256V .
• The Current through an Electric Motor is 6.8A at 230V . Calculate the Impedance of the Motor ?
[ U = I x Z ] ( Transpose for Z ) ↔ Z = U/I . = 230 ÷ 6.8 = 33.82Ω .
• An A.C. Coil has an Impedance of 430Ω . Calculate the Voltage if the Coil Draws a Current of 0.93A ?
[ U = I x Z ]
= 0.93 x 430 = 400V

* Calculate the Inductive Reactance of a Coil which has an Inductance of 0.03 henrys when Connected to a 50Hz Supply ?
[ XL = 2πfl ] = 2 x 3. 142 x 50 x 0.03 = 9.42Ω .
* Calculate the Inductive Reactance of a Coil . when Connected to a 60Hz Supply ?
[ XL = 2πfl ] = 2 x 3. 142 x 60 x 0.03 = 11.31Ω . it can be seen from this Calculation that the Frequency Increases the Inductive Reactance will also Increase .
* An Inductor is Required to Cause a Voltage Drop of 180 Volts when a Current of 1.5Ais Passed through it at a Frequency of 50Hz :- Calculate the Value of the Inductor ?
[ UL = I x XL ( this is Ohms Law with Inductive Reactance instead of Résistance )
Transposed : [ U/I = XL ] 180 ÷ 1.5 = 120Ω . XL = 2πfl ↔ 120 = 2 x 3. 142 x 50 x L .
Transposed : 120 -------- ( 2 x 3. 142 x 50 ) = 0.381H . [ On Calculator enter 120 ÷ ( 2π x 50 ) = answer 0.382H )

PS. A Big Thank You would be Nice Amber

 

[Spudnik]

In response to Ambers signing off above, it would be appreciated if all who read the thread use the "Thanks" button, even if it is just on individual posts that you have found helpful. Its not much to ask, and wont take a second to do.

Amber spends a LOT of time compiling and posting information for us all to benefit from and is totally UNPAID for his work.

Thank you Amber..... You are a goldmine.

 

[amberleaf]

Cables for Fixed Wiring . [ am using the Term Fixed for Understanding ] House Bashing Yeah
Cable has Solid Cores ( Conductors ) and thus Doesn’t bend ( i.e. it isn’t a Flexible Cord ) it is Used in Places where it won’t be Moved once it is Installed .
Flexible Cords ( Flexes ) Connecting Electrical Appliances to the Mains Via Plug . Stranded [Flexible ]

Number of Cores .
Three-Core flex is Used on Appliances needing an Earth [ Usually Metal Cased Appliances ]
Two-Core Flex is Used for Double Insulated Appliances [ Look for the Double Insulated Symbol ]

 

[amberleaf]

After Midnight 2.02 minutes past . 4

• How do we most commonly obtain safe working voltages when working on a Construction site ? [ Using a Transformer ] 110V .
* The orange and yellow boxes .
• A device that is designed to switch off an item of equipment foe maintenance comes under the definition of ? [ Isolation ]
* So it can’t be accidentally switched on
• Steel wired Armoured cable is fixed and Supported by means of ? [ Cleats ]
* Clips don’t support . you should use larger types .
• Use of tools on a Construction site supplied by an employer are covered by ? [ PUWER ]
* Comes under Equipment . ]
• The most appropriate method for ensuring accessory boxes are installed level is by using ? [ A spirit level ]
* The good old fashioned . available in many sizes .
• When cleaning up after fixing equipment to concrete structures . you should be cautious of ? [ Dust ]
* What does drilling concrete produce .
• One major danger of using extension leads on a Construction site is ? [ Cutting through the flex ]
* Maybe machinery rolls over it or .
• When considering working on a live installation , what should first be done ? [ A Risk Assessment ]
* Assess the dangers and possibilities and reduce .
• Ladders should be set on an angle and conform to which of the following RATIOS ? [ One for every 4 Up ] Big / H&S ◄◄ CSCS.
* 75° ◄◄
• What is the maximum lifting weight recommended by the HSE for a fit Male ? [ 25kg ] PS. No jokes Please .
* At waist level it’s .
• An 110V transformer designed to be used on a Construction site is Centre Tapped for additional ? [Give 55V to Earth ]
* Reduce voltage to earth .
• Particular care should be taken when using soldering irons that the ? [ Lead has not been burned or damaged ]
* it get Hot .
• The use of Grinding Equipment is covered by the ? [ Abrasive Wheels Regulations ] ◄◄
* Think about how they work .
- Electricity at Work Regulations . N/A.
- COSHH Regulations . N/A.
- IEE Wiring Regulations . N/A.
• What is the most likely outcome of poor manual handling techniques ? [ Back ]
* Keep the …. Straight all the time .
• it is recommended that screwdrivers and certain hand tools are insulated to ? [ 1000V ]
* VDE insulated
• A light switch is defined as circuit ? [ Control ] as we kwon the 17th Edition . Functional ◄◄
* On and Off .
• The type of accident that kills most Construction workers is ? [ Working from Height ] ◄◄ -&-s / CSCS
* Falling . Dropping .
• A battery forms part of a simple electrical system and is commonly known as the ? [ Source ]
* Right at the start .
• The correct method of fixing surface socket outlets to concrete walls is to use ? [ Woodscrews and expanding plugs ]
* Standard red/brown types & screws .
• The fixing of termination lugs onto copper cables should be performed using ? [ A crimping tool set at the right conductor size ]
* Any type of device that performs the correct function
• Surface conduit is fixed and supported by the means of ? [ Saddles ]
* should be the shape of the conduit and planned and fixed beforehand .
• The best method of fixing surface sockets to metallic stud walling is the use of { Spiral plasterboard fixings ]
* Think fast and convenient .
• Before we begin work on an installation , we need to check what surfaces we will be fixing to this information may most likely be found in the ? [ Specification ]
* Should detail all the information about an installation .
• Before using , a ladder must be in inspected by ? [ The intended user ]
* Hopefully you before you get up there .
• Electrical operated power tools should be ? [ Checked before and after use ] -&-s H&S - CSCS.
* Better safe than sorry .
• All electrical related hand tools should ? [ Undamaged and fit for intended purpose ]
* Do what they are meant to do .
• Before performing a manual handling task . what is the first thing you should ? [ Assess the whole task ]
* Look at the big Picture .
• Completed work at the end of an electrical installation is recorded on ? [ as fitted drawings ]
* Tells you where things are .
• When using soldering items . care should be taken ? [ Against toxic fumes ]
* Melting metal gives off what .
• To reduce financial losses and inconvenience from the theft of tools and materials we should be ? [ Stored in a Locked container ]
* Security is all .

 

[amberleaf]

● Any electrically conductive object will conduct an induced current if it is placed in a changing magnetic filed :
● Eddy currents are circular induced current :
● Eddy currents generate their own magnetic fields :

● A magnetic field is generated anytime an electrical current flows through a conductor .
● The magnetic field around the conductor flows in closed loop’s .
● Wrapping the wire into a coil creates an Electromagnet .
● Wrapping the wire around a piece of Iron creates a Solenoid .

● Field intensity is a term used to describe the strength of the Electromagnetic field .
● Field intensity is determined by the amount of Electrical current flowing in the wire .
Field Direction ● The right-hand-rule can be used to describe the direction of the Electromagnetic field . [ Current ]

The Parallel Circuit :-
Like the Series circuit . Parallel circuits also contain a Voltage ( Current ) source as well as wires and other components .
The main difference between a Series circuit & a Parallel circuit is in the way the components are connected . In Parallel circuit the electricity has several paths that it can travel .

 

[amberleaf]

►This is my Understanding .

Identify : for each of the following a typical use of the following Drawings .

1) Assembly Drawings .
2) Block Diagrams .
3) Circuit Diagrams .

1) Shows . the component parts ( in an exploded view ) of the equipment which is to be worked on . Could be used for dismantling & reassembling equipment – plant .
2) A. Block diagram shows the sequence of operation-control set out as Blocks on a plan . it does not show the Actual position of the Item .
3) Shows . the wiring system of the Plant including . Isolation . may Not necessarily show the connections of components .

[ PS. Chaps . Dan is Complaining about all The Thank You.s Coming in all at the Same Time ] The Forum can’t handle it Amber . ] ◄◄ Now am Stop Asking ???

 

[amberleaf]

How does an increase in temperature affect the résistance of most materials ?
a) It doesn’t
b) Minimal affect
c) As temperature rises so does a material’s resistance *
d) As temperature rises a material’s resistance will decrease

What is resistivity ?
a) An individual material’s resistance to a current *
b) The amount of electrons flowing past a point per second
c) The electromotive force pushing a current

What is an electromagnet ?
a) A material, when inserted into a
strong magnetic field exhibits a magnetic force of its own
b) A material which is attracted to magnets
c) A material which is not attracted to magnets
d) A field produced when there is an electrical current flowing through a conductor *

Which of the following is a conducting material ?
a) Iron
b) Silicon *
c) Glass
d) Gold

10 What does e.m.f. stand for ?
a) Electro-magnetic force
b) Electrical-motive force
c) Electro-motive force

Why is copper better than aluminium as a conductor ?
a) It’s cheaper
b) It’s more freely available
c) It has better conductivity *
d) It has a greater tensile strength for use in overhead lines

What does RCD stand for ?
a) Residual current device
b) Residual contact device *
c) Reckless current deviation
d) Residual current dexterity

What is a semiconductor ?
a) A material which is a good conductor
b) A material which is a good insulator
c) A material which is neither a good conductor nor a good insulator and sits somewhere between the two *
d) A material which is both a good conductor and a good insulator

Which of the following is not an advantage of high-frequency fluorescent circuits ?
a) Higher lamp efficacy
b) First-time starting
c) Noise free
d) The initial cost is cheaper than glow-type switch starts *

Which of the following is not an example of discharge lighting ?
a) Semi-resonant starting
b) High frequency
c) Stroboscopic effect
d) Tungsten halogen lamps *

Which of the average life of a linear tungsten halogen lamp ?
a) Up to 500 hours
b) Up to 1000 hours
c) Up to 2000 hours *
d) Up to 2500 hours

q1 What common type of steel conduit is best for in damp conditions ?
a) Galvanised
b) Solid-drawn
c) Black enamel
d) Seam-welded

q2 What are set bends in steel conduits used for ?
a) When a conduit run changes direction by less than 90 degrees *
b) To go round a corner or change direction by 90 degrees
c) When a surface levels changes or when terminating into a box entry
d) When passing obstacles

What is a strap saddle used for ?
a) Fixing conduit to an even surface
b) Fixing conduit to a cable tray or steel framework *
c) Fixing conduit to girders and I-beams
d) Used when it is necessary to clean around the conduit

What type of trunking is used in offices . schools , & Colleges ? [ Dado trunking ] **
a) Multi-compartment trunking
b) Skirting trunking *
c) Busbar trunking
d) Flush cable trunking

What clips or ties will not maintain circuit integrity during a fire ?
a) Copper
b) steel
c) Nylon *
d) Copper-coated

What type of conduit would you use within metal stud partitioning ?
a) PVC conduit
b) Flexible conduit **
c) Steel conduit *
d) Plastic conduit

What does MCB stand for ?
a) Moulded Circuit Breaker
b) Major Current Boomer
c) Miniature Circuit Breaker *
d) Major Calibration Mechanism

(4)

 

[amberleaf]

Got the Wife’s glasses on . must go to Specsaver.s …. a) Residual current device *
what would you use on Agricultural / Farm . " Hint " Cows Urinate Corrodes What ? : [ steel conduit , Galvanised No ] take you best Guess try the 17th Edition . What can you wash down easy !!!!!!!!!!!!

 

[amberleaf]

1 Why is plastic conduit more appropriate for farm installations ?
a) It’s cheaper * [ Heavier Conduit ] 17th Edition ……….
b) It retains heat
c) It expands better than alternatives
d) It’s more suitable for damp conditions

6 Which type of diagram would be most useful when running a cable between two buildings on a site
a) Site plan *
b) Block diagram
c) Location diagram
d) Circuit diagram

 

[amberleaf]

Power Factor Correction

What is Power Factor ?

Power Factor is a characteristic of alternating current, and can be defined as the ratio of working power to total power.

Alternating current has the following components

* Real Power – [ Power which produces work ( kW )
* Available Power – [ Power delivered or total volt amp ( kVA )
* Reactive Power – [ Power needed to generate magnetic fields required for the Operation of Inductive electrical equipment ( kVAR ) No useful work is performed with Reactive Power .

Therefore the unitless Power Factor is obtained from
Power Factor = Real Power = kW / Available Power kVA

Power Factor is generally represented as a percentage or a decimal. Perfect power factor, often referred to as unity power factor would be 100% or 1.0.

[ power factor is only ( 1 ) or less . & rarely ( 1 ) ]

What is Power Factor Correction?

All flowing current causes losses in the supply and distribution system. A load with a power factor of 1.0 results is the most efficient loading for the supply and a load with a power factor of 0.6 will have much higher losses in the supply system. These loses have to be paid for, and result in higher utility bills. It is possible to modify the supply and distribution system to bring the power factor closer to unity. This is called power factor correction.

Correcting Power Factors

The simplest form of power factor correction, sometimes referred to as static correction, is by the addition of capacitors in parallel with the connected inductive load. The resulting capacitive current is a leading current and is used to cancel the lagging inductive current flowing from the supply. The capacitors can be applied at the starter, or the switchboard or at the distribution panel. Note that power factor correction should not be used when a motor is controlled by a variable speed drive.
Rather than correcting each individual load, the total current supplied to the distribution board can be monitored by a controller which switches capacitor banks to maintain the power factor at its predetermined setting. The controller switching in capacitors as new loads come on line, and switching out capacitors as loads go off line. This type of correction is sometimes referred to as bulk correction.

Common Inductive Loads

Commonly used electrical equipment that provide an inductive load include lighting circuits, heaters, arc welders, distribution transformers and electric motors. …… Etc

** power factor correction offers improved voltage regulation due to reduced lower voltage drop. Also, by considering power factor correction at the design stage it is possible to reduce capital investment through reduction in the size of transformers, switchgear and cable diameters.

( K)

 

[amberleaf]

● What are the Examples of Inductive Load !!!!!!!!!!

Some well known examples are a motor, relay, solenoid valve, electromagnet, transformer, lamp ballast, and an ignition coil. However, in electronics, even a piece of wire can be considered an inductive load because it has the property of inductance. An inductor is a device that produces a magnetic field while an electrical current is passed though it.

● What are the Examples of Inductive Load !!!!!!!!!!

Any devices that have coils of wire in there manufacture can be classed as inductive loads. e.g. motors, solenoids and contactor coils are a few. Example of resistive loads can be baseboard heaters, filament light bulbs, toasters and stove top elements.

● What is the difference between a Resistive Load & an Inductive Load !!!!!!!!!!!!!

Resistive Load An electrical load which is characteristic of not having any significant inrush current. When a resistive load is energised, the current rises instantly to it's steady-state value, without first rising to a higher value. An electrical load in which voltage and current are converted to energy in the form of heat; i.e., an electrical heater, incandescent bulb.
Inductive Load An electrical load which pulls a large amount of current (an inrush current) when first energized. After a few cycles or seconds the current "settles down" to the full-load running current.
The time required for the current to "settle down" depends on the frequency or/and the inductance value of the Inductive load

( K )

 

[Phil]

Singles Old Wiring :- ( 2 – Way Wiring Problem ) “ Megger at the Ready “

A lot of Testing !! or Trial & Error
Attention to which Wire was which when you Removed the Old Switches . ( it depends on how the Electrician Set it Up )

The Three Reds without more info can’t say which Wire goes where but again the ( Common ) is the Important One so trying all ( Three Combinations ) should not take Long . ( Mark Wires 1 . 2 . 3. and Try each one in ( Common ) with Other Two in ( L1 . L2 ) Until it Works .

It is also suffice to mention that if however you mixed up the Wires . or Terminated them upside down . it will not Cause any major problems. The worst you faced might be a Light that cannot be switched Off or a Switch that works in the Opposite direction . in any case . a Small Relocation of the Wires for the Affected Switch should take care of the Problem

The Wiring is as Following :
( Red ) to ( L1 ) ↔ ( Red ) to ( L2 ) & Black to ( Common ) if Twin Used .
Black Wire should be your ( Common ) as a Rule . But not all the Time ??

It should be The ↔ ( Three Red Wire or One Black ) or Three – Single ( Red Wire ) ↔ ( Two Red Wires & One Black Wire ) Two – Way
( One ( Red Wire ) which is in the ( Com : Mains ) ↔ ( L1 Red Wire 2 ) ↔ ( L2 Red Wire 3 ) ↔ Two – Way ▼
( One ( 1 Red Wire / Switch Live / Return ) to Light Fitting ) ↔ ( L1 Red Wire 2 ) ↔ ( L2 Red Wire 3 ) Plus Earth ????

It should be ( Red Wire ” Mains “ ) from the Three-Single Cable’s which is in the ( Common Position ) on your First Light Switch .
You should have ( Red or Black / Two – Red ( from the Light Switch ) Connected across ( L1 ) & ( L2 ) Now you have the Three- Single Wires Connected across ( L1 ) & ( L2 ) & ( Common ) Permanent Live Switch Live

( Two – Way switches work together to Operate a Light from Two different Locations ) 3 – wires in One Light Switch . Plus Earth ????

You may come across . One ( Red ) to the ( Common ) & Bridge to other ( Common(s) ) Two Switches . 3-Gang 2-Way.
( To find out which are Strappers or Singles . Join One end of a Twin & Earth together & Bell Out ) Continuity

Feed from Consumer Unit
( Only a Switched Live . if we turn off the Light at the Switch there is No power to the Ceiling Rose ) ( Not Use Loop in Loop Out Drawbacks )

( Make sure that they are Earth in a 2-Gang Switch Old Wiring or Any Lighting )
You may see this in Old Wiring :- Twin & Earth . Earth Used as ( Common ) Permanent Live ( Rare !! )
Twin & Earth because the CPC is Bare throughout its Length & doesn’t get away from the Fact there is not a CPC at the Switch . ( Previous Electrician )

514.4.2 : Protective Conductor . The bi-colour combination Green -&-Yellow shall be used exclusively for identification of a Protective Conductor and this combination shall not be used for any other purpose .

Single-Core cables that are Coloured Green-&Yellow throughout their length shall only be Used as a Protective Conductor and shall not be Over-Marked at their Terminations . Except as permitted by Regulation 514.4.4.

( 2392-10 : The Only way is the Right Way . Any Compromise is Wrong . in these Circumstance’s Use the Regulation’s as your Excuse / Lever / Justification for Insisting that it Need’s to be Ripped Out & Started again .

Radial Circuit is used for Lighting Circuits

Loop-in-Wiring :-
With loop-in-wiring . the Cable from Ceiling rose to switch has 3 Conductors . Namely Earth . Unswitched Return Live & Switched Live .

Sockets :- RCDs ?? May be Prone to Nuisance Trips
RCDs is not a Regulation requirement for most Socket(s) . Only Socket(s) likely to be Used by Outdoor Equipment are required to be Powered via an RCD . ( Let me Ask you . Would you Use a dedicated Socket feeding a Fridge Freezer on a RCD ( Cause Defrosting ) non-RCD side

Sockets may be Wired on Ring Circuits or Radial Circuits ( Radial !! More Copper . Connection Faults have greater Consequences ) . Mostly Rings are Used . as they use Less Copper for most Circuit Layouts . They have Safety Advantages over Radial Circuits can provide more power . and cover More Floor Area per Circuit .
20A Radials use 2.5mm2 or 4mm2 Cable : p/363 . Regs
32A Radials use 4mm2 Cable :

It is Common to have a Ring Dedicated just for Sockets in the Kitchen Since that is where you will find many of the Highest power Consuming Appliance
( Design ) – Kitchens are supplied by One Ring Circuit . [ Larger Kitchens – Load & Diversity – Calcs ]

Electric Shower . Own high Current Cable . Cooker Own high Current Cable . [ p/362 – Regs . (iii) Connecting Cookers . Ovens & Hobs with a rated power Exceeding 2 kW on their Own dedicated Radial Circuit ]

Why the Breaker had Tripped ?? Resetting a Breaker !! Unable to hold the “ On “ Position (i) Mechanical Problem Rare ) (ii) it is Retripping for a Short Circuit it’s doing it’s Job )

[ Solution !! Another good way is to Take the Panel’s Cover Off . Remove the Wire from that Breaker . & see if it Resets & Stay On ]
?? But if the Original does stay “ On “ when Deprived of it’s Wire . Then it has Indeed been Responding to a [ Short Circuit ] Yeah

Blinking or Flickering Lights
[ Solution !! you may be dealing with a Poor Connection somewhere in your System . it is Commonly at an Outlet . Light . Switch / or Loose Connection ]

The Short Circuit . ( ● Most Breakers can stand up to Repeated Shorting )
Since the Short . the Earth Fault . the Arc-Fault ( Unintended Continuity )
A Live to Earth Short [ Breaker Earth Fault ) is more Common than a Line to Neutral Short .

First :- On the dead Circuit . Unplug everything & turn all On/Off switches Off . & turn Only One Switch the Other Way . “ Try Reset “ then On if the Breaker stays On . one of the Items you Disconnected from the Circuit has the Short in it . so reconnect One at a Time . Turning power back On each time That should Identify the Culprit .

The Causes of Problems ??
The biggest Cause for Electrical Problems in Old Homes is simply the Age of the Home / Wiring

Thanks to G

 

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Rafter’s : ( Do Not Drill into them )
Are used to form the Roof Structures of the Building & are Supported by the Top Plate .

Ceiling Joist’s : ( Check : Cables through Joist’s O.S.G. p/59 ) & Part P .
Are horizontal framing member’s that sit on top of the wall framing . They form the Structural framework for the Ceiling . ( if there is a Floor above . these Ceiling Joist’s become . Floor Joist’s ) & also form the Structural Framework for the Floor above .

Understanding Electricity :
A Household Electrical System can be Compared with a Homes plumbing system .
Electrical Current flow’s in Wires in much the same way that water flows inside pipes . both Electricity & Water enter the home . are Distributed throughout the house . do their “ Work “ & Exit .

In plumbing “ Water “ first flows through the pressurised Water supply System . in Electricity Current first flows along Live Wire’s . Current flowing along Live Wire’s also is Pressurised . the Pressure of Electrical Current is called Voltage .

Large Supply pipes can carry a Greater Volume of Water than small pipes . Likewise . Larger Electrical Wire’s carry more Current than Small Wire’s . this Current – Carrying – Capacity of Wire’s is called “ Amperage “

Water finally leaves the home through a Drain System . which is NOT Pressurised . Similarly . Electrical Current flows back through Neutral Wire .
The Current in Neutral Wire’s is NOT Pressurised ( At Zero Voltage ) ↔ ( Current Return’s UNDER no Pressure Normally ↔ This is not under Fault Condition’s )

 

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17th Edition Conduit : Definitions p/22 . A part of a closed wiring system for cables in Electrical Installations. allowing them to be drawn in & /or replaced , but not inserted laterally .
( Plain English )
Conduit : ( A Metal or Plastic Tube used to Protect Wire’s ◄ ) - Metal Conduit / Continuity / Wander Lead may be Used .
Continuity : an Uninterrupted Electrical Pathway through a Circuit or Electrical Fixture .

 

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Silver : is the most Conductive Material . it’s Price . etc .
Copper ; is the Second most Conductive Element . ( Copper as the Best Alternative )

( Plain English Simplified ) Theory Behind : ( V + / - ) → ( I ) ( R )

( V ) = Voltage ( Pressure behind Current Flow )
( I ) = Amp’s ( Flow of Current )
( R ) = Ohm’s ( Résistance or how much Current will flow Through a Component )

High Voltage moves a Large Current .
Low Voltage moves a Small Current .

 

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A Fundamental Question .
Will the Protection Device Function ?? During a Fault Condition ?

- Let’s consider the Difference between Fault Level Current Rating & ( PSCC ) Prospective Short Circuit Current . the Fault Level Current Rating can be seen on a ( MCB ) Circuit Breaker . Example as 6kA . ↔ This means that the ( MCB ) is able to “ Withstand up to 6000 Amp’s for a Short Period without being Destroyed . ( Tripping Time depends on the MCB )

( PSCC ) Prospective Short Circuit Current . measured in an Installation is used to Consider whether the Circuit is Capable of Carrying sufficient Current so as to Trip the Overload Device in the Specified Time .

High values of ( PSCC ) Prospective Short Circuit Current . can vary Dramatically due to small changes in Impedance . ??
V = Z x I
Example : I = 230 / 0.03Ω = 7666. Amps
Or : I = 230V ÷ 0.01Ω = 23000 Amps

Notice : The vast change in Current for a very Minor Difference in Impedance , ( Low Impedance is very Difficult & High Current is Required )

 

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Re: PIR reporting and competent persons.

“Apprentices “ Useful Junk “ BS-951 ( We Use this Day in & Day Out without thinking about it ) Yeah . All in a Word

Specifies the performance and important Mechanical requirements for metal clamps that are used to provide Mechanically and Electrical Sound earthing and bonding connections to metal tubes. The information . relates to the correct selection and installation of such clamps within electrical installations.

► Misuse of BS-951

Cases of misuse of BS 951 clamps are occasionally found, some examples of which are given below. ( You will see this in your Travels ! )

Fitting a BS-951 Clamp to the Armour or Metallic Sheath of a Cable ( the Why’s !! )

BS 951 states that clamps to this standard are Not intended for connection to the armour or sheath of a cable and requires the packaging of the clamp to include the warning “ Not intended for Use on the Sheath or Armour of a Cable “. This is because the Action of tightening the clamp is liable to damage the cable, for example by crushing the bedding or insulation or by causing the metal in a lead sheath to Cold – Flow . Such damage may result in High Résistance and unreliability in the electrical connection between the clamp and the armouring or metallic sheath, and may even result in an electrical fault within the cable, Fitting a BS 951 clamp to the armour or metallic sheath of a cable is therefore Unacceptable .

Fitting a BS-951 Clamp which is Unsuitable for the Pipe Diameter & / or Cable Size :

A BS 951 clamp must be correctly selected for both the size of pipe or tube to which it is to be fitted and the size of cable. Fitting a clamp which is unsuitable in either of these respects is liable to be a departure from the requirements of Regulations 526.1 and/or 526.2 of BS 7671 relating to durable electrical continuity, adequate mechanical strength, and appropriate selection of a means of connection.

● To avoid corrosion due to electrolytic action, Aluminium Labelsof BS 951

Installing a Clamp in an Inaccessible Position :

Like all types of electrical connection that are not excused by Regulation 526.3 of BS 7671, the electrical connections between a BS 951 clamp, the pipe (or other tube) to which it is attached, and the protective conductor connected to its terminal must be accessible for Inspection , Testing and Maintenance (Regulation 543.3.3 refers).

BS-7671 Requirements ! ( The Only Trouble with the Regulations . they are all Scatted to the 4 Winds )

● Warning notice-earthing and bonding connections ( 514.13 )
● External influences (Section 522 )
● Connections between conductors and a conductor and equipment (526.1)
● Accessibility of connections (526.3 )

Résistance to Corrosion :

Clamps to BS 951 are made in a choice of different metals, to suit differing levels of corrosion that are likely to be encountered in service. In order to comply with the requirements of Section 522 (Selection and erection of wiring systems in relation to external influences) of BS 7671, it is important to select a clamp which is suitable for the expected conditions in the particular location where it is to be installed. For example, some clamps are intended for use only in dry conditions, whilst others are suitable for damp locations such as bathrooms. Some manufactures of clamps use different colours to indicate the type of application and environmental conditions for which the clamp is intended, similar to the colours shown in the illustration below. Where doubt exists as to the suitability of a clamp for use in a particular environment, advice should be sought from the manufacturer.

Terminations :

The termination on a BS 951 clamp for the protective conductor is separate from the means of tightening and locking the clamp for making electrical contact with the tube.

A screw termination is capable of accepting one of the following: Etc .

● a conductor clamped under a screw head provided with a captive washer so that the screw head does not act directly on the conductor; Etc.

● “ Phil can this be move this to the Right Place “ Please . Thank you . Amber . Ta.