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

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“ Rcd's “

Fire detection circuits must be supplied independently of other circuits and not protected by an Rcd protecting multiple circuits. 560.7.1 All circuits in a bath shower room must be protected by a 30mA RCD. P166, 701.411.3.3
Where applicable an RCD notice must be fixed on or next to the CCU 514.12.2 An RCD should not be used as a main switch 314.2 If the maximum Zs values for a circuit in a TN systems cannot be met, the circuit may be protected by a 30mA RCD. 531.3.1
If the maximum Zs values for a TN systems cannot be met, the installation may be protected by an 100mA RCD and treated as a TT systems . 531.3.1 : 411.5.1 : 411.5.2 : 411.5.3
Unless specifically labelled or suitably identified, all 13A socket outlets must be protected by a 30mA Rcd. 411.3.3
In a TN systems , the part of a lighting circuit in a bath or shower room is required to be 30mA RCD protected. 411.3.3 , 701.411.3.3

Where a cable is buried in a wall or partition at a depth of less than 50mm on either side it must be sufficiently mechanically protected against penetration OR RCD protected AND installed either horizontally within 150mm of the top of the wall or vertically within 150mm of the angle formed where two walls meet or run horizontally or vertically to an accessory, luminaire or CCU 522.6.6 , 522.6.7 . This applies to a cable in a partition constructed using metallic parts other than fixings irrespective of the cable depth. 522.6.8

Surface run cables do not require RCD protection. OSG p22

A single RCD protecting a TT systems must be installed at the origin of the installation unless the part of the system between the origin and the RCD fulfils the requirements for protection by Class 11 equipment or equivalent insulation 531.4.1

All Electrical equipment must be accessible for operation , inspection & testing maintenance and repair. 132.12

Rcd Test Procedure

Many RCD test meters have a facility where tests can be carried out during the positive or negative half of the supply cycle. For tests 1 & 2 the RCD operating time to be recorded is the longer of the two measured during the half cycle tests.

DO NOT press the test button on the RCD before testing as this can temporarily reset a faulty RCD

Test 1
Adjust the current setting on the test meter to 100% of the rated trip current of the RCD and perform a test. A general purpose BS4293 RCD should operate within 200mS . A general purpose BS-61008 RCD or RCBO to BS-61009 should operate within 300ms

Test 2
An RCD provided for Basic Protection should have a rated TRIP current not exceeding 30mA If the RCD is rated at 30mA , adjust the current setting on the test meter to 150ma ( x5 ) and perform a test. The RCD must operate in a time not exceeding 40mS.
Test 3
Adjust the current setting on the test meter to 50% of the RCD trip current and perform a test. The RCD should not operate within 2 seconds
The Test Button : Finally operate the RCD by pressing its test button

 

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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 : ←←←

 

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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

 

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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 .

 

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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 :

 

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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 , ←

 

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Polarity : ( Competent Person ) ( Dead Test ) Apprentice : you'll get some Q/A on 17th Edition

Polarity tests are made to verify that every fuse or single-pole device is connected in the Phase Conductor Only , ( 612.6 )
> Edison screw lampholders should be connected so that the Phase conductor is connected to the Centre contact : <
Lampholders to BS-EN 60238 . in circuits having an earthed Neutral conductor , centre contact bayonet and Edison screw lampholders have the outer or screwed contacts connected to the Neutral conductor ( 612.6 (ii)


The Tests should be Carried Out before the Installation is Energised Using a Low-Reading Ohmmeter or Continuity Test Instrument ,
Much of the Polarity Testing can be Carried Out during the process of testing CPC continuity by using the ( R1 + R2 ) method .
However Polarity should also be confirmed after connection of Supply ,

Earth Fault Loop Impedance ( External to the Installation ) ( 612.9 ) ≈ ≈ ( Live Test ) ≈ ≈ ***
The external earth fault loop impedance ( Ze ) is one of the Supply characteristics to be recorded ( Ze ) can Only be measured by testing at the Origin of the Installation . “ Before Testing “ ( The Earthing Conductor must be Disconnected from
The Main Earthing Terminal and the Entire Installation must be Isolated from the Supply ,
The purpose of Disconnecting the Earthing conductor is to ensure that measurement is not affected by Parallel Paths of , for Example :
The Main Bonding Conductors . The Instrument to be Used is an Earth Fault Loop Impedance Test Instrument :

The procedure is as follows :
* open the main switch :
* disconnect the earthing conductor :
* check test instrument and leads :
* apply test probes to the live side of the main switch and disconnected earthing connection :
* check polarity indication for correct connection :
* press the test button and record results :
* reconnect the earthing conductor must be disconnected from the main earthing terminal and the entire installation must be isolated from the supply ,
The purpose of disconnecting the earthing conductor is to ensure that measurement is not affected by Parallel Paths of , for Example .
The Main Bonding Conductors . The instrument to be used is an Earth Fault Loop Impedance test instrument ,

The procedure is as follows :
* open the main switch :
* disconnect the earthing conductor :
* check test instrument and leads :
* apply test probes to the live side of the main switch and disconnected earthing conductor :
* check polarity indication for correct connection :
* press the test button and record result :
* reconnect the earthing conductor before restoring the Supply :

Circuit Impedance Measurement :
The type of instrument to be used is the same as that used for external impedance testing , The earth loop impedance ( Zs ) of every circuit should be measured at the point furthest from the incoming Supply ,
The test must be undertaken with all protective conductors connected :

Prospective Fault Current : ( 612.11 ) ≈ ≈ ( Live Test ) ≈ ≈ ***
This is the largest current that would flow in the event of a fault between live conductors or between a live conductor and the earthing conductor . the value should only be measured at the origin of the installation .
Only the largest value is recorded The earthing conductor , main bonding conductor and CPC should all be connected .
The instrument used is an earth fault loop impedance test instrument with a prospective fault current range ,

A Polarity Check should also be made on Incoming Supply : ( PS: I don’t know if you still get this at Collage ) ≈ ≈ Live Testing , ≈ ≈

Continuity of Protective Conductors . ( 612.2.1 ) GN-3 ( Dead Test )
Main & Supplementary Equipotential Bonding :

There are Two options for Undertaking this Continuity Test : ( R1 + R2 ) method (1) or wander lead ( R2 ) only method (2)

When testing for continuity of main and Supplementary Equipotential Bonding , it is usual to apply the ( R2 ) only test ,
Before carrying out this test to confirm continuity of the appropriate bonding conductor ,
It is necessary to avoid the measurement of parallel paths ,
Accordingly: it is advisable to disconnect one end of the bonding conductor to be tested and any intermediate connections with services .
The wander lead method is undertaken by connecting one lead of the test instrument to the main earthing terminal with a long lead ,
With this long lead and the other lead of the instrument , make connection at the remote end of the bonding conductor .
Remember to Null the test leads of their instrument for this test , otherwise the measured value will include the résistance of the wander lead ,
It is also important to remember to Re-Null the test leads of the instrument only when the ( R2 ) test is completed ,
Otherwise , again the measured value would give an incorrect measurement ,
The ( R1 + R2 ) method applies to circuit protective conductors and their associated phase conductor ,
The Procedure is as follows :
* Isolate the Supply :
* Connect the phase & cpc conductors together at the distribution board :
* Measure the résistance between phase and cpc at each outlet or point :
* Measure and record the résistance between phase & cpc at the furthest point :
* Remove the temporary phase / cpc connection :

The ( R1 + R2 ) method can also be used to check the polarity of each circuit .
When testing ( R1 + R2 ) at each point it is also necessary to operate the switch in order to confirm an open circuit condition
When the switch is in the off position , therefore confirming polarity ,

Continuity of Ring Final Circuit Conductors :
Requires five distinct steps to be undertaken . The confirmation of continuity of ring final circuits
( Unfortunately some contractors appear to omit steps 2 , 3 , 4 , ) the procedures are as follows :

Step 1 : ( Checking Continuity of Live and Protective Conductors of a Ring Final Circuit ) ↔ ( little r1 & r1 : r n & r n : cpc & cpc )
Conductor Continuity
Isolate the Supply ,
Measure the résistance of the End–to–End Phase , Neutral and Circuit Protective Conductors Separately And record the values ,
The values of the Phase & Neutral conductors will indicate whether or not the conductors are continuous ,
Moreover , the Phase & Neutral conductors should have the same value of résistance .
The results taken should be recorded as ( r1 , r n & r2 , ) Schedule of Test Results include the provision for recording
Such measurements , then a ( tick ) should be entered in the column marked Ring .

Step 2a : ( Ring Final Circuit with No Spur ) Lead on Line & Neutral / Lead on Line & Neutral :
Phase-to-Neutral :
Connect the incoming Neutral to the outgoing Phase of the circuit and vice versa , Measure the résistance between the pairs
And note the results , The reading obtained should be half that obtained for either the Phase or Neutral conductor in Step 1 :

Step 2b :
Measure between Phase & Neutral at each point on the Ring Circuit .The readings should be much the same as in step ( 2a )
Sockets wired as spurs will give a slightly higher reading , Schedule of Test Results include the provision for recording
Step 3 :
Phase-to-Earth :
Repeat steps 2a & 2b but using the Phase and CPC conductors , This test also confirms polarity , The highest value obtained should be recorded in the ( R1 + R2 ) column ,
Step 4 :
Reconnect the conductors :
Insulation résistance , Before proceeding with this Test it must be ensured that all equipment vulnerable to an insulation résistance test
Has been disconnected , The Insulation is normally measured between Live conductors and Live conductors to Earth
The procedure for insulation résistance testing between Live conductors is as follows :
* Isolate the Supply :
* Disconnect all current using equipment and close all switches :
* Disconnect equipment vulnerable to a test
* Check instrument and leads :
* Select test voltage range :
* Connect the instrument and record values of Phase to Neutral between Phases , and Phases to Neutral for ( 3 Phase-Supply ) and
Between Live conductors :

Step 3 : ( Ring Final Circuits with No Spur )
Step 4 : ( Ring Final Circuits with Unintentional Spurs )

 

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“ Résistance and the Conductor “ 2392-10 : -&- you will be asked something like this Q/A

Résistance is directly proportional to length and inversely proportional to C.S.A. simply this means that More Length > More Résistance ,
and Less Length > Less Résistance , Also the Greater the C.S.A. the Less the Résistance , and the Smaller the C.S.A. the Greater the Résistance ,

"WHEN YOU GO TO WORK GUYS LOOK OUT FOR YOUR SELF AND YOUR PARTNER"

"PLAN ON STAYING ALIVE"

There are Proper Procedures that we all Should Follow when Working on Potentially Live Equipment. Testing Dead and Locking Off should be something that we do as a habit, and Remember to always Check your Tester on a Live Circuit before Using it to Test a Circuit Dead. Unfortunatly some Foremen and Contractors seem to forget that if One of Us gets Seriously Hurt or Killed in Order for them to get a Job Done Faster or Cheaper they are Liable and will be Prosecuted. Remember NOT Taking Chances is how “ Young Electricians get to be Old Electricians :

! Don't be a hero and stay alive !

Regulations : 12 / 13 / 14 / 16

Changes in the 17th Edition Jason can you move it to the right place Amberleaf

NOTE 1: This is not an exhaustive list.
NOTE 2: Particular attention is drawn to Section 701. This section now allows socket-outlets (other than SELV and shaver supply units to BS-EN 61558-2-5 ) to be installed in locations containing a bath or shower 3m horizontally beyond the boundary of zone 1.
• Regulation 131.6 – adds requirements to protect against voltage disturbances and implement measures against electromagnetic influences. In doing so, the design shall take into consideration the anticipated electromagnetic emissions, generated by the installation or the installed equipment, which shall be suitable for the current-using equipment used with, or connected to, the installation.
• Regulation 132.13 – requires that documentation for the electrical installation, including that required by Chapter 51, Part 6 and Part 7, is provided for every electrical installation.
• Chapter 35 – Safety services, recognizes the need for safety services as they are frequently regulated by statutory authorities whose requirements have to be observed, e.g. emergency escape lighting, fire alarm systems, installations for fire pumps, fire rescue service lifts, smoke and heat extraction equipment.
• Chapter 36 – Continuity of service, requires that an assessment be made for each circuit of any need for continuity of service considered necessary during the intended life of the installation.
• Chapter 41 – Protection against electric shock, now refers to basic protection, which is protection under normal conditions (previously referred to as protection against direct contact), and fault protection, which is protection under fault conditions (previously referred to as protection against indirect contact).
- Chapter 41 now includes those requirements previously given in Section 471 of BS 7671:2001.
- Chapter 41 now requires that for the protective measure of automatic disconnection of supply for an a.c. system, additional protection by means of an RCD with a rated residual operating current (IΔn) not exceeding 30 mA and an operating time not exceeding 40 ms at a residual current of 5 IΔn be provided for socket-outlets with a rated current not exceeding 20 A that are for use by ordinary persons and are intended for general use, and for mobile equipment with a current rating not exceeding 32 A for use outdoors. This additional protection is now to be provided in the event of failure of the provision for basic protection and/or the provision for fault protection or carelessness by users of the installation.
- Note that certain exceptions are permitted – refer to Regulation 411.3.3.
- Chapter 41 includes Tables: Table 41.2, Table 41.3 and Table 41.4 for earth fault loop impedances (replacing Tables Table 41B1, Table 41B2 and Table 41D). These new tables are based on a nominal voltage of 230 V (not 240 V), hence the values are slightly reduced. It has been clarified that where an RCBO is referred to in these Tables, the overcurrent characteristic of the device is being considered.
- Chapter 41 includes a new Table 41.5 giving maximum values of earth fault loop impedance for RCDs to BS EN 61008-1 and BS EN 61009-1.
- FELV is recognised as a protective measure and the new requirements are detailed in Regulation 411.7.
- Chapter 41 includes the UK reduced low voltage system. Requirements are given in Regulation 411.8.

• Chapter 42 - Protection against thermal effects, includes requirements in Section 422 Precautions where particular risks of fire exist (These requirements were previously stated in Section 482 of BS 7671:2001).
• Chapter 43 - Protection against overcurrent, includes those requirements previously given in Section 473 of BS 7671:2001. Information on the overcurrent protection of conductors in parallel is given in Appendix 10.
• Chapter 44 - Protection against voltage disturbances, includes a new Section 442, Protection of low voltage installations against temporary overvoltages due to earth faults in the high voltage system and due to faults in the low voltage system. This new section provides for the safety of the low voltage system under fault conditions including faults in the high voltage system, loss of the supply neutral in the low voltage system and short-circuit between a line conductor and neutral in the low voltage installation.
• Section 443 - Protection against overvoltages of atmospheric origin or due to switching, retains the existing text from BS 7671 and adds regulations enabling designers to use a risk assessment approach when designing installations which may be susceptible to overvoltages of atmospheric origin.
• Chapter 52 - Selection and erection of wiring systems, now includes busbar trunking systems and powertrack systems.
- It is now required to protect cables concealed in a wall or partition (at a depth of less than 50 mm) by a 30 mA RCD where the installation is not intended to be under the supervision of a skilled or instructed person, if the normal methods of protection including use of cables with an earthed metallic covering, mechanical protection (including use of cables with an earthed metallic covering, or mechanical protection) cannot be employed. This applies to a cable in a partition where the construction includes metallic parts other than fixings irrespective of the depth of the cable.
- Table 52.2 Cable surrounded by thermal insulation, gives slightly reduced derating factors, to take account of the availability of material with improved thermal insulation.
• Chapter 53 – Protection, isolation, switching, control and monitoring. Simplification means that requirements previously in Chapter 46, Sections 476 and 537 of BS 7671:2001 are now in this single chapter. Chapter 53 also includes a new Section 532 Devices for protection against the risk of fire, and a new Section 538 Monitoring devices.
• Chapter 54 - Earthing arrangements and protective conductors. The requirement that a metallic pipe of a water utility supply shall not be used as an earth electrode

 

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is retained in Regulation 542.2.4 which also states that other metallic water supply pipework shall not be used as an earth electrode unless precautions are taken against its removal and it has been considered for such a use. An example of other metallic water supply pipework could be a privately owned water supply network.
- A note to Regulation 543.4.1 states that in Great Britain, regulation 8(4) of the Electricity Safety, Quality and Continuity Regulations 2002 prohibits the use of PEN conductors in consumers’ installations. Regulation 543.7 has earthing requirements for the installation of equipment having high protective conductor currents, previously in Section 607 of BS 7671:2001.
• Chapter 55 - Other equipment, includes new additional requirements in Regulation 551.7 to ensure the safe connection of low voltage generating sets including small-scale embedded generators (SSEGs).
• Section 559 - Luminaires and lighting installations, is a new series of Regulations giving requirements for fixed lighting installations, outdoor lighting installations, extra-low voltage lighting installations, lighting for display stands and highway power supplies and street furniture (previously in Section 611 of BS 7671:2001).
• Chapter 56 - Safety services, has been expanded in line with IEC standardization.
• Part 6 - Inspection and testing, was Part 7 of BS 7671:2001. Changes have been made to the requirements for insulation resistance; when testing SELV and PELV circuits at 250 V, the minimum insulation resistance is raised to 0.5 MΩ; for systems up to and including 500 V, including FELV, the minimum insulation resistance is raised to 1.0 MΩ.
• Part 7 - Special installations or locations, was Part 6 of BS 7671:2001. The structure of Part 7 includes the following changes.
- Section 607 in BS 7671:2001 relating to high protective conductor currents has been incorporated into Chapter 54.
- Section 608 in BS 7671:2001 relating to caravans, motor caravans and caravan parks has been incorporated into
- Section 708: Electrical installations in caravan/camping parks and similar locations and Section 721: Electrical installations in caravans and motor caravans.
- Section 611 in BS 7671:2001 relating to highway power supplies is now incorporated into Section 559.
- The following major changes are incorporated in Part 7:
~~ Section 701 Locations containing a bath tub or shower basin.
~~ Zone 3 is no longer defined.
~~ Each circuit in the special location must have 30 mA RCD protection.
~~ Supplementary bonding is no longer required providing the installation has main bonding in accordance with Chapter 41.
~~ This section now allows socket-outlets (other than SELV and shaver supply units to BS EN 61558-2-5) to be installed in locations containing a bath or shower 3m horizontally beyond the boundary of zone 1.
• Section 702 - Swimming pools and other basins. This special location now includes basins of fountains. Zones A, B and C in BS 7671:2001 are replaced by zones 0, 1 and 2.
• Section 703 - Rooms and cabins containing sauna heaters. Zones A, B, C and D in BS 7671:2001 are replaced by zones 1, 2 and 3 (with changed dimensions).

• Section 704 - Construction and demolition site installations. The reduced disconnection times (0.2 s) and the 25 V equation no longer appear.
• Section 705 - Agricultural and horticultural premises. The reduced disconnection times (0.2 s) and the 25 V equation no longer appear. Additional requirements applicable to life support systems are included.
• Section 706 - Conducting locations with restricted movement, was Section 606 in BS 7671:2001.
• Section 708 - Electrical installations in caravan/camping parks and similar locations, now includes the requirement that each socket-outlet must be provided individually with overcurrent and RCD protection.
The following new sections are now included in Part 7:
• Section 709 - Marinas and similar locations
• Section 711 - Exhibitions, shows and stands
• Section 712 - Solar photovoltaic (pv) power supply systems
• Section 717 - Mobile or transportable units
• Section 721 - Electrical installations in caravans and motor caravans – previously in Section 608 of BS 7671:2001
• Section 740 - Temporary electrical installations for structures, amusement devices and booths at fairgrounds, amusement parks and circuses
• Section 753 - Floor and ceiling heating systems.
Appropriate changes have been made to Appendices 1 to 7, in particular the methods and tables used in Appendix 4.

Earth Loop Impedance and Prospective Short Circuit (PSC) Testing Methods

Why Earth Fault Loop Impedance Test is Necessary ?

Earth fault loop impedance is the path followed by fault current when a low impedance fault occurs between the phase conductor and earth, i.e. "earth fault loop". Fault current is driven round the
loop by the supply voltage. The higher the impedance, the lower the fault current will be and the longer it will take for the circuit protection to operate.

To make sure the protection operates fast enough, the loop impedance must be low. Every circuit must be tested to make sure that the actual loop impedance does not exceed that specified for the protective device concerned. It is recommended that the (Ze) test be done first. This test, done at the distribution board, gives the loop impedance of the circuit, excluding the installation. The (Zs ) test, which includes the circuit tested in the (Ze) test as well as including the installation resistance, must be done next.

In most homes, basic shock protection is done by coordinating an earthing circuit with automatic switches in the indoor wiring circuits. This quickly cuts off supply to an earthing circuit where a fault occurs and touch voltage exceeds an acceptable limit. Proper protection against electric shock hazards is given when the TT wiring system complies with: Ra x Ia <50, where Ra is the sum of the resistances of earth bars and protective conductors and Ia is the maximum current of the protection system. Ra multiplied by Ia should not be more than 50 V, i.e. the maximum voltage one can touch will not exceed 50 V in the event of an earth fault.

Earth Fault Loop Impedance Testing :

The value of the earth fault loop impedance is the sum of transformer coil winding resistance, phase conductor (L1) resistance and the protective conductor (PE) resistance as well as the source earth resistance and installation resistance.
The Ze earth fault loop impedance measurement is made on the supply side of the distribution board and the main means of earthing, with the main switch open and all circuits isolated. The means of earthing will be isolated from the installation's earthing system (earth rods) bonding during the test. The Ze measurement will confirm the earth fault loop impedance as the sum of the resistances of the transformer coil winding, phase conductor or supply side and protective conductor resistance, but not the installation earth resistance

The Zs earth fault loop impedance should be tested at the furthest point of each circuit. In most cases the circuit breaker needs to be bridged out. The total earth fault loop impedance can be measured by plugging a loop tester into a socket outlet, or in some cases with an external earth probe. The value of the earth fault loop impedance is the sum of the resistances of the transformer coil winding , phase conductor (L1) and protective conductor (PE) as well as source earth and installation earth resistance.
When using an external earth probe, the earth fault loop impedance can be measured by touching an external probe directly to an earth bar, collector and connection point of an earth bar. The same measurement can be done by touching the earth probe to exposed, conductive parts of equipment in the circuits and exposed metal parts.

Prospective short circuit current (PSC) testing
The prospective short circuit or fault current at any point in an electrical installation is the current that would flow in the circuit if no circuit protection operated and a complete (very low impedance) short circuit occurred. The value of this fault current is determined by the supply voltage and the impedance of the path taken by the fault current. Measurement of PSC can be used to check that protective devices within the system will operate within safety limits and as per the safe design of the installation. ( PSC ) is normally measured between the Phase and Neutral at the DB or at a socket outlet.

 

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2391-10 : Use the wording

Routine Electrical Inspection and Report-( sometimes known as Home buyers or sellers Report)

Electrical installations should not be left without any attention for the periods of years between formal periodic inspections. Also not everyone may require a formal periodic inspection; you may wish to choose a less comprehensive routine electrical inspection instead. Typically these are required in the years between periodic inspections to monitor for deterioration, or to assess condition before or after house purchase, or if you know the wiring to be relatively modern and did not require extensive testing.
The following is a list of what is covered in the inspection:

Visual inspection
o Main protective bonding bonding conductor
o Supplementary protective bonding conductor ( where required )
o Breakages or damage
o Wear or deterioration
o Overheating
o Missing parts
o Switchgear obstructions
o Security of enclosures
o Adequate labelling
o Loose fittings

Function test
o Switchgear
o Equipment switching
o Circuit breakers

Test
o RCD trip times
o Earthing (loop impedance) and Polarity of ring and radial socket circuits

Reports

On completion of the inspection a report will be provided, detailing the condition of the installation, results of tests carried out, any recommendations and conclusions as to the relative safety of the installation.

Cost- Domestic – Homes only


Domestic- Homes …………………………………………........ £ Please contact us for prices ,
Additional Consumer-Units ….. i.e. Garage … etc ………. £ Please contact us for prices ,

Please Note :
Prices shown are not subject to the addition of vat ,

Extent of the Work

When entering into an agreement for electrical inspection and testing of a building under your control it is a fundamental requirement that the extent and limitations of the inspection and testing are fully described. It is recommended that the following be agreed prior to beginning the work, and we can assist you in determining your exact requirements for inspection and testing.
As it is neither practical nor possible to inspect all parts of an installation, we will agree a sampling process. This is normally in the order of 10%-20% of all accessories, fittings and control equipment.

For much of the testing the electrical system will be switched off. If this is a problem we can arrange the work at times when this is more convenient.
We will agree before commencing the work the amount of down time that can be tolerated and arrange a provisional program for switching off – totally, and individual areas or distribution boards if required.
Reports

On completion of the Inspection and Test a report will be provided, detailing the condition of the installation, results of all tests carried out, a list of any faults, and recommendations and a conclusion as to relative safety of the installation.

Insulation Resistance of the Electrical Installation ( 612.3 )

The purpose of these tests is to verify that:
i. there are no short circuits between current carrying conductors or between live conductors and earth.
ii. There is no reduction in insulation resistance due to damage or dampness.
Test Instrument:
An insulation resistance tester having a DC test voltage which depends upon the supply voltage (Table 61 ) is required.

The polarity tests are necessary to verify that: ( 612.6 )

i. All fuses, single pole switches and protective devices are connected to the phase conductor only.
ii. The Centre Contract of Screw Type Lamp holders is Connected to the Phase Conductor with Outer or Screwed Contacts Connected to the Neutral Conductor,
iii. Wiring is Correctly Connected in Socket Outlets and Similar Accessories.

RCD tests ( Max test current for 100mA RCD is 100mA ) 2392-10 : this will come up ←←←← -&-

Testing Methodology :
Inspection &Testing and Certification

Electrical Installation Certificate
The Regulations require that an Electrical Installation Certificate in the form set out in Appendix 6 together with Schedule of Test
Results shall be given to the person ordering the work :

Regulation : ( 632.4 )
Requires any defect or Omissions revealed by Inspector shall be made good before an Electrical Installation Certificate is issued ,

Regulation : ( 631.4 ) ( 632.3 )
Requires : the Electrical Installation Certificate shall be signed by a competent person or persons staring that to the best of their
Knowledge and belief the Installation has be designed , constructed , inspected and tested in accordance with BS-7671 and permissible deviations being listed ,

Note 1 :
Requires : the Electrical Installation Certificate may Require Three Signatures :
Multiple Signature Electrical Installation Certificate,
(1) The Designer ,
(2) Person Constructing the job
(3) Inspection & Testing Engineer ,
Note 2 :
An individual may sign all three parts if he/she has designed , constructed , inspected & tested installation ,
Note 4 :
Certificates :
Single Signature Electrical Installation Certificate,
Where design ,construction ,inspection and testing are the responsibility of one person, a Certificate with a single signature may replace the multiple signature form ,
Note 5 :
Electrical Installation Certificate will accompany the following :
(1) Schedule of Inspections :
(2) Schedule of Test Results : ( p-334 )

The Sequence of Tests : GN-3 ,
Initial Tests should be Carried out in the Following Sequence ,

(i) Before the supply is connected , or with supply disconnected as appropriate

(1) Continuity of Protective conductors , including main & Supplementary Equipotential bonding : ( 612.2.1 )
(2) Continuity of Ring Final Circuit Conductors : ( 612.2.2 )
(3) Insulation Résistance : ( 612.3 )
(4) Polarity ( 612.6 ) by Continuity Methods :
(5) Earth Electrode Résistance : ( Using Earth Electrode Résistance tester )

Initial Tests should be Carried out in the Following Sequence ,
(ii) With the Electrical Supply Connected re-check Polarity Using an Approved Voltage Indicator before Further Testing ( GS-38 )
(1) Earth Electrode Résistance, Using an Earth Fault Loop Impedance Tester (2) Earth Fault Loop Impedance : ↔ ( 612.9 ) Phase / Neutral – Impedance ,
(3) Prospective Fault Current ( 612.11 ) Additional Loop , Higher for Line / Neutral Test ,
(4) Additional Protection : ( 612.10 ) ↔ Testing Residual Current Operated Devices
(5) Functional Test : ( 612.13 ) ↔ of Switchgear and Control Gear

Note : All Test Results should be Recorded on a , Schedule of Test Results complete with Inspection & Test Result Schedules of Inspections must be provided to the person ordering the work ,

Continuity of Protective Conductors :
Continuity of protective conductors including main and supplementary bonding ( 612.2.1 )

Every protective conductor, including the earthing conductor, main and supplementary bonding conductors, should be tested to verify that the conductors are electrically sound and correctly connected.

Test method 1 detailed below, as well as checking the continuity of the protective conductor, also measures ( R1+R2 ) which, when added to the external impedance ( Ze ) enables the earth-fault loop impedance ( Zs ) to be checked.

Note : (R1+ R2) is the sum of the resistance of the phase conductor R1 and the circuit protective conductor R2 :

Instrument - Use a low-reading ohmmeter :

The resistance readings obtained include the resistance of the test leads. The resistance of the test leads should be measured and deducted from all resistance readings obtained unless the instrument can auto-null. ( Subtract )
Test method 1
Connect the phase conductor to the protective conductor at the distribution board or consumer unit so as to include all the circuit. Then test between phase and earth terminals at each outlet in the circuit. The measurement at the
circuit's extremity should be recorded on the schedule of test results and is the value of (R1 + R2) for the circuit under test.
The test should be carried out before connecting any exposed-conductive-parts, which may provide parallel paths to the protective conductors.

 

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Test method 2

Connect one terminal of the continuity tester to the installation main earthing terminal, and with a test lead from the other terminal make contact with the protective conductors at various points on the circuit, e.g. light fittings, switches, spur outlets etc. The resistance of the circuit protective conductors R2 is recorded on the test result schedule. Bonding conductor continuity can be checked using this test method. One end of the conductor and intermediate connections with services may need to be disconnected to avoid parallel paths.
Where ferrous enclosures have been used as the protective conductors, e.g. conduit, trunking, steel-wire armouring etc. the following procedure should be followed:

inspect the enclosure along its length for soundness of construction

perform the standard ohmmeter test using the appropriate test method described above.
Instrument - Use a low-reading ohmmeter for this test.

If the inspector feels that there may be grounds to question the soundness of this conductor, a further test may be performed using an a.c. ohmmeter which has a test voltage not exceeding 50 V and can provide a test current approaching 1.5 times the design current of the circuit excepting that it need not exceed 25 A.
Care needs to be taken when using high-current testers, as sparking can occur at a faulty joint. This test should not be carried out if this could be dangerous. Instrument - Use a high-current, low-impedance ohmmeter for this test.
( high current micro-ohmmeter suitable for measuring very low resistances )

TEST METHOD 1 - LINKING PHASE AND CPC :
Connect a temporary link between the phase conductor and the protective conductor at the distribution board. Using a low-reading ohmmeter test between the phase and earth terminals at each outlet in the circuit. The measurement obtained at the furthest point of the circuit should be recorded on the results schedule. This reading is the value of R1 + R2 for the circuit.

Note:
“ Main switch switched off “
Temporary link between Phase and CPC at the consumer unit. All fuses should be removed or MCB's switched off.

Remove temporary link when testing is complete.

TEST METHOD 2 - LONG LEAD METHOD

Connect one terminal of the ohmmeter to the earth terminal at the distribution board via a lead long enough to reach the furthest extremity of the circuit under test. The other terminal is then used to make contact with each outlet on the circuit.

Once resistance of the test leads is subtracted from the readings the corrected figure can be recorded.
Note:
All fuses out or MCB's switched off. Main switch switched off.

RING FINAL CONTINUITY TEST :
Purpose:

A test is required to verify the continuity of each conductor including the circuit protective conductor (CPC) of every ring final circuit.
The test results should establish that the ring is complete and has no interconnections.

Test Instrument required a Low Resistance Ohmmeter.

Step 1

Determine the resistance of each loop.

r1 - r2

r,n 1 – r,n 2

CPC1 - CPC2

Once the above readings have been established this will either confirm that the CSA of the CPC is the same as the phase conductor or smaller.

Step 2

Link-out Phase1 to Neutral 2 and Phase 2 to Neutral 1.
Now measure the resistance at every socket outlet between Phase and Neutral. The reading obtained should be the SAME at every socket outlet if the ring circuit has been connected up correctly.

The reading should be either ¼ of (Phase Loop + Neutral Loop) or ½ the reading of the Phase conductor loop.

Example

R1 - R2 = 1Ω

R,n 1 – R,n 2 = 1Ω

CPC1 - CPC2 = 1Ω

With Phase and Neutral cross linked, the reading at every socket outlet will be:

a) Phase loop 1 Ω + Neutral loop 1 Ω = 1 + 1 = 0.5 Ω
........................ 4 ............................ 4

b) Phase loop 1 Ω = 1 = 0.5 Ω ( 1÷ 2 = 0.5Ω )
....................2 ............. 2

Note: This reading is recorded on Test Certificate ,

Step 3

Remember

R1 = Resistance of Phase Conductor

R2 = Resistance of Circuit Protective Conductor

Now to measure R1 + R2 value of the ring final circuit.

Cross Link

Phase1 to CPC2

CPC1 to Phase2

Now measure the resistance at each socket outlet between Phase and CPC.

The reading at every socket outlet should be approximately the same.

Phase loop 1 Ω + Neutral loop 1 Ω = 1 + 1 = 0.5 Ω

....................4............................ 4 ( 1 +1 = 2 ÷ 4 = 0.5Ω


If one of the socket outlets is a spur, the reading here will be most likely the highest. It is this reading which needs to be recorded on the test result schedule under the column R1 + R2.

Note 1:
When carrying out this test you will automatically confirm the socket outlet, polarity, therefore there is no need to carry out a separate polarity test.
Note 2:
If the CPC cross sectional area is smaller e.g. 2.5/1.5, the resistance of the CPC will be 1.67 times higher than the phase resistance. Therefore, the readings measured at every socket outlet will differ slightly.

Note:

After connection of the supply, polarity should be confirmed using an approved voltage indicator (with leads conforming with HSE Guidance Note GS38).

Type of Inspection : 2392-10 most of them will come up Q/A ,

On demand Periodic Inspection and Test :
Periodic Inspection Report
Inspection Schedule & Schedule of Test Results

Documents :
Electricity at Work Regulations 1989
Health and Safety Executive Guidance Note GS38
BS7671 – Requirements for Electrical Installations

Personnel

First periodic test – designer / installer
Further periodic tests – Tester / Inspector
Extent & Limitations agreed with – person ordering the work

Instruments :
Continuity ring final circuit – low reading ohmmeter
Insulation resistance – insulation resistance tester
Live polarity – GS38 compliant voltmeter or test lamp.

Increase in Conductor Resistance :
Increase in ambient temperature
Increased circuit length - additions
Decreased conductor cross section – modifications

CPC Continuity :
At every Socket
Phase and CPC
Highest Value, therefore Circuit Value, for ( R1 + R2 )

Wiring systems not requiring separate CPC :
PVC-PVC insulated flat cable with CPC ( twin & earth )
MICC
SWA

Ring final circuit test :
P & N tested to ensure a valid ring circuit
If an interconnection existed

(i) CPC continuity, Figure-of-eight, (R1 + R2) measurement. Or
(ii) Polarity

Insulation Résistance, 600V Discharge lighting :
Insulation Résistance Tester
1000V d.c.
1.0 MΩ
Insulation Resistance 230V Installation :
500V
1.0 MΩ
2 MΩ
Polarity testing :
So that operating the device cuts line potential from the accessory protected.
Because live parts are only energised when lamp is in place.
To ensure supply is connected correctly at source.
Loop impedance :
Ze = External Loop Impedance
R2 = Resistance of circuit protective conductor
1.2 = Operating temperature correction factor. ( 1.2 is for bunched 70oC thermoplastic cables used at maximum operating temperature )
RCD tests : Loop impedance test determines that an earth fault loop path exists , Functional test determines that the RCD will actually operate in the event of a fault – electro-mechanical test using the ‘T’ button. , Max test current for 100mA RCD is 100mA

 

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Scenario :
Testing :
* Periodic Inspection and Test, plus an Initial Inspection and Test, for the new part of the installation . * Periodic Inspection Report , Electrical Installation Certificate, plus Schedules of Test Results and Schedules of Inspections , * The person ordering the work gets the originals * First periodic test determined either by statute or by the designer * Statutory document = Electricity at Work Regulations 1989 * Non-statutory = BS7671, HSE Guidance Note 38

Human senses :
* Sight , * Smell , * Hearing ,
* Limitations of the inspection should be agreed with the person ordering the work , * BS3036 Fuses will not carry the large fault current. (They have a safe breaking capacity of either 1 or 4 kA) * PSCC between phases can be taken as twice the maximum measured value between any phase and neutral.
* Although the circuit is single phase, 230V, discharge lamps generate much higher voltages when striking. Should the insulation resistance tests, therefore, be carried out at 1000V, with a minimum acceptable value of 1 M ohm ? Personally, I’d say, no – we’re testing the wiring and switchgear, but it’s a debatable point.

What is GS38 ? ( Test Lead ) 2392-10

Guidance Note GS38, published by the Health and Safety Executive (HSE), sets out in clear and concise terms the features that any instruments and meters should have if they are to be used to carry out electrical tests in accordance with BS 7671. In order to comply with the Electricity at Work Regulations 1989 it is critical that any competent person carries out electrical testing safely, and this guidance note draws attention to the risks of using test instruments that do not meet the GS38 standard. In brief, some of the requirements for test instruments include:
• The test probes should have finger guards, ideally 4mm or 2mm of exposed conductive tip (to prevent the user accidentally making contact with either the probes or live conductors under test) and should be fitted with a High Breaking Capacity inline fuse or fuse-and-resistor combination with a low current rating (to prevent the probes rupturing under high short-circuit currents and/or damaging the test instrument if incorrect range settings are used, typically drawing more than 500mA).

• The test leads should be adequately insulated to suit the environment in which they’re being used, are coloured differently from each other so as to be distinguishable, are flexible, are capable of handling the maximum current range of the test instrument and are shrouded or sheathed to protect against mechanical damage, securely connect the leads to the test instrument and safeguard against the possibility of direct contact with live parts.

 

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Question 1 :
State the necessary action that should betaken by an inspector on discovering a damaged socket outlet with exposed live parts
during a periodic inspection and test :
GN3 Page 14 - 1.2 ( Required Competence ) ( 634.2 )
(1) Make an immediate recommendation to the client to isolate the defective part :
Question 2 :
State the documentation that should accompany an Installation Certificate or Periodic Inspection Report ,
GN3 Page 14 - 1.3.1 ( Certificates and Reports ) ( 631.1 : 632.1 )
(1) Electrical Installation Certificate , together with a Schedule of Inspections
(2) and a Schedule of Test Results ,
Question 3 :
Why is it necessary to undertake an Initial Verification ?
GN3 Page 17 - 2.1 ( Initial Verification ) ( 610.1 : 611.2 : 612.1 )
(1) Confirm that installation complies with designers intentions ,
(2) Inspected and Tested Constructed, in accordance with BS 7671 ,
Question 4 :
State the requirements of Chapter 61 of BS 7671 with regard to initial verification ,
GN3 Page 17 - 2.1 ( Initial Verification ) ( 611.2 )
(1) All fixed equipment and material complies with applicable British Standards or acceptable equivalents ,
(2) All parts of the fixed installation are correctly selected and erected ,
(3) No part of the fixed Installation is visibly damaged or otherwise defective ,
Question 5 :
Identify four Non-Statutory documents that a person undertaking an inspection and test need to refer to ,
General Knowledge
BS 7671
IEE On-Site Guide
Guidance Note 3 Guidance Note : GS 38 , ( HSE )
Question 6 : Which non-statutory document recommends records of all maintenance including test results be kept throughout the life of an installation ? GN3 Page 17 - 2.1 (Initial Verification )( 631.1 )
The Memorandum of Guidance on The Electricity at Work Regulations 1989 ( HSR25 ) (EAWR Regulation 4(2)
Question 7 :
Appendix 6 of BS 7671 allows the use of three forms for the initial certification of a new installation or for an alteration or an addition to an existing installation. State the title given each of these certificates ,
GN3 Page 18 - 2.2 ( Initial Verification )
(1a) Multiple signature Electrical Installation Certificate ,
(2a) Single signature Electrical Installation Certificate ,
(3a) Minor Electrical Installation Works Certificate ,
(1b) The Multiple signature certificate allows different persons to sign for design , construction , inspection & testing,
And allows two signatories for design where there is mutual responsibility . where designers are responsible for identifiably separate parts of an installation , the use of separate forms would be appropriate .
(2b)where design , construction , inspection and testing are the responsibility of one person, a certificate with
A single signature may replace the multiple signature form ,
(3b)This Certificate is to be used only for minor works that do not include the provision of a new circuit ,
Such as an additional socket-outlet or lighting point ton an existing circuit ,
Electrical Installation Certificate , 2392-10 :
to be used when One person is responsible for the design Construction , inspection & testing of an Installation , p-332 ,
Approved Contractor issuing the Certificate has not been responsible for the design / or the inspection & testing of the
Electrical work ( p-333 certification of the three elements must be carried out separately using , ↔ the three sections headed ↔ Designer ( no 1 ) .. ↔ Designer ( no 2 ) .. first periodic (T)-(1) Designer / Installer , further periodic (T)-(2)
Tester / Inspecter , ( Construction (No 2) : Inspector ( Inspection / Testing ( No 3 )
Question 8 :
Under what circumstances would it be appropriate to issue a single signature Electrical Installation Certificate ?
GN3 Page 18 - 2.2 ( Certificates )
Where design, construction inspection and testing is the responsibility of one person ,
(2b)where design , construction , inspection and testing are the responsibility of one person, a certificate with
A single signature may replace the multiple signature form ,
Question 9 :
State the information that should be made available to the inspector ,
GN3 Page 18 - 2.3 ( Required information )
(1) Maximum demand , expressed in amperes , kW or kVA per Phase ( After diversity is taken into account )
(2) the Number and type of live conductors of the source(s)of energy and of the circuits used in the installation ,
(3)Type of earthing arrangements, used by the installation and any facilities provided by the distributor for the user ,
(4)the Nominal voltage(s) and its characteristics including harmonic distortion ( 313.1 ),
(5) the nature of the load current and supply frequency , (6) the prospective fault current at the origin of the installation , ( PFC ) (7)The Earth Fault Loop Impedance ( Ze ) of that part of the system external to the installation , (8) The suitability for the requirements of the installation, including the maximum demand , (9) Type and rating of overcurrent protective device acting at the origin ,of the installation ,
Note : These characteristics should also be available for safety services such as ( UPS ) and Generators ,

Question 6 : ops Which statutory document recommends records of all maintenance including test results be kept throughout the life of an installation ? GN3 Page 17 - 2.1 (Initial Verification )( 631.1 )
The Memorandum of Guidance on The Electricity at Work Regulations 1989 ( HSR25 ) (EAWR Regulation 4(2)

 

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Inspection , Testing , Certification & Reporting :

Testing Continuity of Protective Conductor at a Lighting Switch by Wander Lead Method ,
Instrument : set on Ohms “ Continuity ↔ 20Ω ( Dead Test )

One Lead on Earthing Terminal at CCU / One Lead on the Earthing Screw on the Back-Box : you have Continuity = 0.41Ω

The Wander Lead Method , ( R2 )
This method is used principally for testing protective conductors that are connected to the main earthing terminal ( Main Equipotential bonding conductors , Circuit Protective Conductors and so on ) The correct Polarity of circuit connections will need to be Verified separately ,

Where a continuity test involves the opening of enclosures etc. that part of the installation will need to be isolated ,
One terminal of the continuity test instrument ids connected to the main earthing terminal with a long lead ( or “ wander Lead “ ) and ,
With a lead from the other terminal, contact is made with the protective conductor at every position to which it is connected in that circuit ,
Such as at socket-outlets, lighting points, fixed equipment points, switches, exposed-conductive-parts and extraneous- conductive-parts,
By this means, provided that no parallel paths are present, the continuity of the protective conductor back to the main earthing terminal can be verified , and its Résistance measured ,

A main or supplementary bonding conductor can be tested by simply attaching the leads of the test instrument to each end of the conductor, having temporarily disconnected one end of that conductor to remove parallel paths ,

Continuity testing of a Ferrous Enclosure using the wander lead method ,

Where a Ferrous Enclosure , such as Steel Conduit or Steel Trunking is used as a Circuit Protective Conductor,
The Integrity of the Enclosure should be verified for compliance with BS-7671, where reasonably practicable by Inspection & Testing

Inspection is to confirm the soundness of the enclosures conductive path , the inspector should indentify any deterioration such as excessive corrosion or the ability of any joints to provide durable Electrical Continuity and Adequate Mechanical Strength ,

Where Safe to do so, Testing of the Conduit or Trunking can be carried out by the Measurement of ( R1+ R2 ) or the Wander Lead method ,
Although these are ( Dead Tests ) both of these test procedures may require access to enclosures containing live parts ,
Therefore → ( Safe Isolation Must be Carried Out ) ← prior to gaining access , to prevent contact with any live parts ,
→ ( Before carrying out the Continuity test, “ Check that “ :

* Access to the Equipment is Not-Restricted , and once the Consumer Unit Cover is Removed , “ Check that “ :
* The basic Protection inside the Consumer Unit meets or exceeds the Requirements of IP2X or IPXXB , and
* The Terminal Insulated covers are unlikely to be Accidentally Displaced during Testing ,

The Wander Lead Method for Obtaining ( R2 ) values has been Described ,

Instrument : set on Ohms “ Continuity ↔ 20Ω ( Dead Test )

One Lead on the Earthing Screw on the Metal Back-Box : you have Continuity = 0.41Ω
The Other Lead on the Earthing Screw on the Metal Back-Box : ( your working on box –to-box : back to CCU Earthing Terminal , ( R2 )

( R1 + R2 )

For a simple circuit R1 + R2 is the phase conductor + the CPC impedance values and will be in ohms subtract from this any value for the leads that were obtained on the instrument check. The neutral should have the same csa of the phase conductor and should be almost equal to that of the phase impedance depending upon the circuit arrangement. For a three phase circuit the highest impedance is the one that could prevent a protective device operating thus this is the one used in practice against the chart to determine whether or not the reading is low enough and therefore recorded. Polarity can be checked at this point by making sure that single pole switches break the phase conductor and not the neutral or CPC.
Once continuity of all possible circuit combinations have been recorded I would guess that each circuit is tested for insulation resistance using the 500V range of an insulation tester for domestic premises. Although the leads should be shorted together to verify the meter reads zero, I prefer to place one lead on an earth and then verify my contact by connecting the other lead to another earth location close by. Since all wiring would need to be tested it is important to have all the switches are turned on. Where there is two lighting circuits this means that all combinations of the switching needs to be verified. I doubt the exam would go beyond the simple two way circuit.
A reading of zero Megohms could indicate that a shorting wire is still in place or that there is a fault. If a low test is obtained between phase and neutral it could be that a neon is used on a fused spur or that a genuine fault is present.

If tests revealed a fault and I resolved the problem then I would begin the tests again in case during my investigations I had inadvertently disturbed the wiring.

Electrical Inspection Testing & Certification : ( Dead Tests ) df

Electrical Installation Certificate
The Regulations require that an Electrical Installation Certificate in the form set out in Appendix 6 of BS7671 together with a schedule of test results shall be given to the person ordering the work.

Regulation ( 632.4 )
Requires any defect or omissions revealed by the inspector shall be made good before an Electrical Installation Certificate is issued.

Regulation ( 631.4 )
Requires: the Electrical Installation Certificate shall be signed by a competent person or persons stating that to the best of their knowledge and belief the installation has been designed, constructed, inspected and tested in accordance with BS7671 and permissible deviations being listed.

Note 1:
An Electrical Installation Certificate may require three signatures :
(1) The designer :
(2) Person Constructing the Job :
(3) Inspection and Testing engineer.
Note 2:
An individual may sign all three parts if he/she has designed, constructed, inspected and tested the installation.
Note 3:
The Electrical Installation Certificate will accompany the following :
(1) Schedule of Inspections : 2391-10 ↔ Use the Right Wording ← on your Exam
(2) Schedule of Test Result : 2391-10 ↔ Testing Checklist ( 611.3 ) ←←←
“ Test Result Schedule “ “ Inspection Schedule “

The Sequence of Tests :

Initial tests should be carried out in the following sequence:
Before the supply is connected, or with supply disconnected as appropriate
GN-3 ( 612.2.1 ) continuity of protective conductors, including main and supplementary bonding
GN-3 ( 612.2.2 ) continuity of ring final circuit conductors ( R1 + R2 )
GN-3 ( 612.3 ) insulation resistance ( “ High Résistance Using d.c. Voltage )
GN-3 ( 612.6 ) polarity ( by continuity methods )
GN-3 ( 612.7 ) earth electrode resistance, using earth electrode resistance tester ( Method 1 )

With the electrical supply connected re-check polarity using an approved voltage indicator before further testing : ≈ ≈ ≈ ≈

GN-3 ( 612.9 ) earth electrode resistance, using an earth fault loop impedance tester ( Method 2 )
GN-3 ( 612.9 ) earth fault loop impedance : ( Phase / Neutral = Impedance ) where protective measures are used which require a knowledge of ( earth fault loop impedance ) the relevant impedances shall be measured ,or determined by an alternative method , Zs = Ze ( R1 + R2 ) :
Note : further information on measurement of earth fault loop impedance can be found in appendix 14 / p-361
Zs (m) ≤ 0.8 x Uo ÷ Ia : ( 230 ÷ 24A = 9.58 , ( Ze / 0.8 x Zs 9.58 = 7.66
From the City & Guild Chief examiners reports it appears that many get calculations of ( Zs ) ( Ze ) R1 and R2 wrong.
( Zs ) is the sum of ( Ze ) R1 and R2 seems simple enough. Zs = Ze + ( R1+R2 ).
( Ze ) is the external impedance. Although you can calculate the value, it is more normal that the value is obtained by measurement using a suitable instrument or by enquiry.
R1 is the resistance of the phase conductor :
R2 is the resistance of the CPC or circuit protective conductor. :
In practical test situations the value of R1 + R2 is obtained in one test so could in effect be considered as one value say Rt. So the equation would become Zs = Ze + Rt.
So why Z and R ? :
Z is the impedance and applies to AC circuits :
R is resistance and applies to DC circuits :
GN-3 ( 612.11 ) prospective fault current ( Live / Neutral )
GN-3 ( 612.10 ) residual current operated devices ( BS – Only - 200mS ( BS-EN – 300mS :
GN-3 ( 612.13 ) functional test ( Light Switches , switchgear and control gear
Note:
All test results should be recorded on a schedule of Test Results form
Report Forms complete with Schedules of Inspection and Schedules Test Result must be provided to the person ordering the work.

 

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TT , TN-C-S , IT , TN-C Earthing Arrangements :
In Latin earth is called Terra (Terre in French ) so we get Terra Firma, on solid ground.

So the first letter denotes if the supply is connected to Earth or Terra with the capital letter T. If insulated from earth then I is used, I for insulated.

The second letter denotes where the consumers earth is connected to. So T would indicate to earth. So TT means that the supply transformer star point is connected to earth and the consumers equipment is also connected to earth using earth spikes etc.

In an IT system the supply transformer has no connection to earth but the consumers equipment is connected to earth using earthing spikes etc.

N stands for neutral and thus in a TN system the consumers earth is connected to earth via the neutral of the supply.
TN S is where the earth and neutral are fed back to the supplier with separate conductors.
TN C is where the earth and neutral are fed back to the supplier using one conductor. ( PEN )
TN-C-S is where the earth and neutral are fed back to the supplier using one conductor but this time the connection of the earth to the neutral is not directly made at the consumers end thus there are two separate conductors from the premises.

Testing – ( the live tests )
612.8 - Protection by automatic disconnection of supply
612.9 - Earth fault loop impedance
612.10 - Additional protection ( RCDs )
612.11 - Prospective fault current
612.12 - Check of phase sequence
612.13 - Functional testing ( inc. RCDs )
612.14 - Verification of voltage drop
Testing – ( the dead tests ) GN-3
612.2 - continuity of protective conductor’s including main and equipotential bonding
612.2.2 - Continuity of ring final circuits
612.3 - insulation resistance (see table 61)
612.4 - protection by SELV, PELV or protection by separation
612.5 - Insulation resistance of floors and walls
612.6 - Polarity
612.7 – Earth electrode resistance
Testing – ( the dead tests ) GN-3
Table 61 – Minimum Values of Insulation Resistance
Note: some of these values have changed from the previous edition
≥ 1.0 1000 Above 500V ≥ 1.0 500 Up to and including 500V with the exception of the above system ≥ 0.5 250 SELV and PELV Minimum insulation resistance ( M Ω ) Test voltage d.c. ( V ) Circuit nominal voltage ( V )

The correct documentation must be issued to the person ordering the work TYPE OF WORK COMPLETED TYPE OF FORM REQUIRED New installation or change to existing installation Electrical Installation Certificate New installation work that does not include the provision of a new circuit Electrical Installation Certificate or Minor Electrical Installation Works Certificate Alterations or additions Electrical Installation Certificate Alterations or additions that does not include the provision of a new circuit Electrical Installation Certificate or Minor Electrical Installation Works Certificate Periodic Inspection and Testing Periodic Inspection Report

* Electrical Installation Certificate : This form to be used when only one person is responsible for the design, construction and testing of the installation * Electrical Installation Certificate : This requires 3 signatures ( The designer , The constructer , The inspector )
You will need to complete one of these for every installation that has been tested.
The Installation Test Certificate : Minor Works Certificate To be used for minor works only, Not for new circuits, or New installations

Periodic Inspection Report : To be used when “next inspection” date is due – or On change of use - or On change of ownership This is now part of the “sellers pack” when homes are for sale
SPECIAL INSTALLATIONS OR LOCATONS ;
COMPETANT PERSON , From Part 2 Definitions , A person who possesses sufficient technical knowledge, relevant practical skills and experience for the nature of the electrical work undertaken and is at all times able to prevent danger and, when appropriate, injury to himself/herself and others.
Check of phase sequence For multi-phase circuits there is a requirement to verify that phase sequence is maintained
Verification of voltage drop This subject matter was covered previously in Section 523 ( and Appendix 12 ). Regulation 612.14 is short , so briefly familiarize yourself with its content.
Part 6 Inspecting and Testing :
Limited changes in Part 6 with model certificates & reports remaining largely unchanged
Insulation values increased - For systems up to and including 500 V the minimum insulation resistance is now 1MΩ
More detailed requirements are provided in relation to RCD testing
New regulations are included in relation to the checking of phase sequence and verification of voltage drops
Section 610 – General : 610.1

Every installation shall, during its erection and on completion before being put into service, be inspected and tested to verify, as far as is reasonably practicable, that the requirements of the regulations have been met.
Precautions shall be taken to avoid danger to persons and to avoid damage to property and installed equipment.
Section 610 – General
610.2 – See sections 131, 311 to 313 and 514.9.1 for information required for the fundamental principles.
610.3 – The verification shall include comparison of the results with the relevant criteria to confirm that the requirements of the “Regs” have been met.
610.4 – For an addition or alteration to an existing installation. It shall be verified that the addition or alteration complies with the regulations, and does not impair the safety of the existing installation.
Section 610 – General (cont.)
610.5 – The verification shall be made by a competent person .
610.6 – On completion of the verification, according to regulations 610.1 to 610.5, a certificate or certificates, shall be prepared.
Section 611 – Inspection
611.1 – The inspection shall precede testing and shall normally done with that part of the installation under inspection disconnected from the supply.
Section 611 – Inspection (cont)
611.2 – The inspection shall be made to verify that the installed electrical equipment is:-

1.
In compliance with section 511 (this may be ascertained by mark or by certification furnished by the installer or by the manufacturer), and
Correctly selected and erected in accordance with the regulations, and
Not visibly damaged or defective, so as to impair safety.
Section 611 – Inspection
611.3 – the inspection shall include at least the checking of the items on the inspection check list, where relevant to the installation, and where necessary, during erection:
A complete inspection checklist is shown in appendix 6 and also available to download from Forms for electrical contractors - The IET as indeed, are all of the forms that you may require.
2.
Section 611 – Inspection
The Schedule of Inspection
This form will be used for ALL installations
Record all your observations here with either a tick ( ) a cross ( x )or ( N/A ) or ( Lim ) p- 340 / regs
Simply work your way through the form item by item, this will ensure compliance with regulation 611.3.
612 - Testing
The tests of regulation 612.2 to 612.13, where relevant, shall be carried out and the results compared with the relevant criteria.
The tests of regulation 612.2 to 612.6, where relevant shall be carried out in that order before the installation is energized .
Where the installation incorporates an earth electrode, the test of regulation 612.7 shall also be carried out before the installation is energized
612 – Testing
If any test indicates a failure to comply, that test, and any preceding tests, the results of which may have been influenced by the fault indicated, shall be repeated after the fault has been rectified.
Some methods of test are described in the IEE Guidance Note 3 ( when available ), Inspection and Testing, published by the Institute of Engineering and Technology.
Other methods are not precluded provided that they give valid results.
612 – Testing Section 612 details the required tests to be for initial verification. The tests should be carried out in a prescribed sequence, some prior to the circuits being energized.

( 314.1 ) dividing the installation into circuits so as to: -
Avoid danger and minimize inconvenience in the event of a fault
Facilitate safe testing, inspecting and maintenance
( 314.2 ) ( 314.3 ) ( 314.4 )

 

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17th Edition requirements for testing of RCDs The 17th Edition has the following requirements in terms of verification of installed RCDs:

612.8.1 requires the effectiveness of automatic disconnection of supply by RCD to be verified using test equipment meeting the requirements of BS EN 61557-6 ( Electrical safety in low voltage distribution systems up to 1000 V a.c. and 1500 V d.c P-12 Regs ).
– Equipment for testing, measuring or monitoring of protective measures. Residual current devices (RCD) in TT, TN and IT systems). This is to confirm that the relevant requirements of Chapter 41 (Protection against electric shock) are met.

BS EN 61557-6 has requirements for the following tests to be applied to RCDs:
- Non-tripping (50%) test
- Tripping (100%) test
- 5 I∆n ) (500%) test

612.13.1 requires the effectiveness of the integral test facility of an RCD to be verified.
415.1.1 states that where an RCD having an I∆n of 30 mA or less is installed to provide additional protection, its operating time should not exceed 40 ms at a residual current of 5 I∆n .

Recommended test procedures
Although the following tests are not required by BS 7671: 2008 they are a method of establishing that the
device meets the requirements of Chapter 41. Remember, in order for reliable results to be obtained
when performing these tests, any loads should be disconnected from the circuits and/or outlets under test .

Non-tripping test.
The purpose of this test is to confirm that an RCD of any type or trip rating is not overly sensitive and is a measure
intended to enable unsuitable RCDs to be identified and removed from service. The continued presence of overly sensitive RCDs tends to reduce user confidence in such devices and may encourage the adoption of potentially dangerous practices such as the “bridging-out” of RCDs in order to avoid unwanted tripping.

Test procedure - With a leakage current equal to 50% of the rated residual operating current (I∆n ) ( applied, the RCD should not operate.
Tripping current test
The purpose of this test is to confirm that the residual operating current of the protective device is less than or equal to the rated
residual operating current. This is a measure of the continued effectiveness of the device to work as required by
BS 7671 and in accordance with its product specification when installed for the purpose of providing automatic
disconnection in the event of a fault. It does not demonstrate its suitability in terms of providing additional
protection. The test should be performed in both the positive and negative half-cycles.

Test procedure -

General purpose RCD to BS EN61008 and RCBO to BS EN 61009
With a leakage current flowing equivalent to 100% of the rated residual operating current (I∆n ) of the RCD, operation should occur within 300 mS.

“S” type RCD to BS EN 61008 ( incorporating an intentional time delay )
With a leakage current flowing equivalent to 100% of the rated residual operating current ( I∆n ) of the RCD, operation should occur
within a time range from 130 mS to 500 mS.

General purpose RCD to BS 4293 and RCD protected socket-outlets to BS 7288 With a leakage current flowing equivalent to 100% of the rated residual operating current ( I∆n ) of the RCD, operation should occur within 200 mS.

General purpose RCD to BS 4293 incorporating an intentional time delay With a leakage current flowing
equivalent to 100% of the rated residual operating current ( I∆n ) of the RCD, operation should occur within a time range from 50% of
the rated time delay plus 200 ms to 100% of the rated time delay plus 200 ms.

Test to confirm suitability for use to provide additional protection :

The purpose of this test is to confirm the continued suitability of an RCD having a rated residual operating current ( I∆n ) not exceeding 30 mA to
provide additional protection under no-fault conditions ( in the 16th Edition, this was known as supplementary protection against direct contact ).
The test should be performed in both the positive and negative half-cycles.

Test procedure -
With a leakage current flowing equivalent to 500% of ( i.e. 5 times ) the rated residual operating current ( I∆n) of the RCD,
operation should occur within 40 ms.

Confirmation of the effectiveness of the integral test facility :

RCDs have an integral test device to simulate the passing through the detecting device of a residual current. This makes possible periodic testing of the ability of the residual current device to operate. However, it should be remembered
that operation of the integral test button merely confirms the continuing functioning of the electrical and mechanical components of the
RCD. It does not confirm that the device is capable of operating in accordance with the specification of the relevant product standard
or, indeed the requirements of the requirements of BS 7671.

Test procedure - With the supply to the RCD switched on and with the RCD in the “on” position, the button
marked “T” or “Test” on the RCD is pressed. The RCD should switch off. ( 514.12.2 ) recommends that the integral test button of an RCD
is pressed quarterly ( every 3 months ).

Summary :
RCDs should be tested at 50% , 100% and, if providing additional protection 500% of their rated residual operating current ( I∆n ) . In addition, the integral test device should be operated quarterly. Where an RCD is employed to achieve the disconnection time
required by Table 41.1 it is necessary to confirm that the maximum earth fault loop impedances (Zs) stated for a particular sensitivity of RCD in Table 41.5 are not exceeded in the circuit to which they provide protection. More in depth descriptions of both
RCD and earth fault loop impedance testing procedures are given in IEE Guidance Note 3 Inspection and testing