Re-take - Useful Information for 2394 :

[amberleaf]

Certification :

( EICR ) Prospective fault-current ( Ipƒ ) [SUP]2 [/SUP]
( EICR ) External loop-impedance ( Ze ) [SUP]2 [/SUP]

( EIC ) Prospective fault-current ( Ipƒ ) [SUP]2 [/SUP]
( EIC ) External loop-impedance ( Ze ) [SUP]2 [/SUP]

( Note : (2) by enquiry or by measurement

By Enquiry .. Must test to ensure Earth is present .
By measurement : Undertaken in order to prove an earth connection

( Generic Schedule of Test Results ) P/402 .. Correct supply polarity confirmed □

 

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Extracts .
p/400 , Domestic & Similar Installations Condition Report Inspection Schedule

Acceptable condition (✓)
Description : The condition of the particular item inspected has been classed as acceptable

Not Verified (N/V)
Description : A particular item on the schedule is relevant to the installation but has not been verified as to its condition

Limitation (LIM)
Description : A particular item on the schedule is relevant to the installation but there were certain limitations in being able to check the condition

Not Applicable (N/A)
Description : The particular item on the inspection schedule is not relevant to the installation being inspected

Unacceptable condition (C1)
Description : The condition of the particular item inspected has been classed as unacceptable. Immediate danger is present and the safety to those using the installation is at risk (e.g. a live part is directly accessible)

Unacceptable condition (C2)
Description : The condition of the particular item inspected has been classed as unacceptable. There is potential danger and the safety to those using the installation may be at risk (e.g. absence of main protective bonding)

Improvement recommended (C3)
Description : The installation is not dangerous for continued use but the inspector recommends that an improvement could be made in relation to the item inspected (e.g. no RCDs for additional protection are installed)

For the inspector included in Appendix 6 should have a statement highlighting that any older installations designed prior to BS-7671:2008 may not have been provided with RCDs for additional protection. If this is the case then the inspector should record a ( C3 ) classification code as a minimum in relation to item 5.12 of the schedule. This is to highlight that the installation could be improved in this respect.

 

[GLENNSPARK]

Certification :

( EICR ) Prospective fault-current ( Ipƒ ) [SUP]2 [/SUP]
( EICR ) External loop-impedance ( Ze ) [SUP]2 [/SUP]

( EIC ) Prospective fault-current ( Ipƒ ) [SUP]2 [/SUP]
( EIC ) External loop-impedance ( Ze ) [SUP]2 [/SUP]

( Note : (2) by enquiry or by measurement

By Enquiry .. Must test to ensure Earth is present .
By measurement : Undertaken in order to prove an earth connection

( Generic Schedule of Test Results ) P/402 .. Correct supply polarity confirmed □

except this dont...does it...

 

[amberleaf]

The measurement of ( Ze requires disconnection of parallel paths )
whilst ( PFC requires parallel paths ) & therefore these tests at the origin of the supply should be carried out separately.

Where ( Protective measures are used ) that require knowledge of the earth-fault-loop-impedance, as is the case where ( ADS ) is used , Regulation 612.9. requires the relevant impedances , to be measured or determined by an ( Alternative method ) by implication , this makes a demand for testing , Line / Earth-fault-loop-impedance . Etc .

612.9. Earth fault loop impedance ( Zs )
&
612.11. Prospective fault current . ( pƒc )

Prospective fault current ( PFC )

Like many of the modern multifunction testers on the market today, the Megger series displays the ( PFC ) at the same time as the loop test results - in the upper display.

it is important to understand that the measurement of ( PFC ) should not be recorded unless the particular requirements for the test are taken into account - in other words, the measurement of ( Ze ) requires disconnection of parallel paths )) whilst ( PFC requires parallel-paths ) therefore these tests at the origin of the supply should be carried out separately.

The value of earth-fault-loop-impedance may be determined by :

Direct-measurement of ( Zs )
Direct-measurement of ( Ze ) at the origin of the circuit & adding to this the value of ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) measurement during continuity tests :
Zs = Ze + ( R[SUP]1[/SUP] + R[SUP]2[/SUP] )

( Ze ) in order to eliminate any parallel earth return paths . The Earthing-conductor are disconnected for the duration of the test .
Will ensure that the reading is not distorted by the presence of , Gas & Water-service-pipes acting as part of the earth-return-path .

 

[amberleaf]

Do we learn by our mistakes !!! Purpose of Initial Verification

Chief Examiners’ report , 2011 . Blast form the past .

GN-3 , 2011: P/15. refer

The lack of knowledge of the requirements of Guidance Note 3 continues to be apparent in answers given by candidates.

Few candidates were able to correctly identify the purpose on an Initial Verification process as identified in GN-3.

► Purpose of Initial Verification
Initial Verification is carried out on a new installation ( before ) it is put into service .

► The purpose of initial verification is to confirm by way of ( Inspection & Testing ) during construction & on completion , that the installation complies with the design & construction aspects of BS-7671: in so far is reasonably practicable .
610.1 , 611.2. , 612.1.

 

[amberleaf]

BS-7671: P/36 ( Verification )
All measures by ( means ) of which compliance of the electrical installation with the relevant requirements of BS-7671: are checked , comprising Inspection , Testing , & Certification .

P/29 , Inspection
Examination of an electrical installation using all the senses as appropriate .

P/36 , Testing
Implementation of measures to assess an electrical installation by ( means ) of which its effectiveness is proved .
This includes ascertaining values by ( means ) of appropriate measuring instruments , where measured values are not detectable by ( Inspection )

 

[amberleaf]

The Inspection & Testing of new work is known as initial verification . As the Regulation suggests .

BS-7671:2011: Regulation 621.1. States that " Where required " , periodic inspection & testing of every installation shall be carried out in accordance with Regulation 621.2. to 621.5. in order to determine , so far as is reasonably practicable , whether the installation is in a satisfactory condition for continued service .

 

[amberleaf]

Useful Junk .

Determination of 3 - phase fault current .

Highest single phase value measured = 2.28kA
( 2.25kA , 2.28kA , 2.25kA )

By calculation : 2.28 x √3 = 3.95kA
An approximation can be done as ( 2 x ) the reading .. 2 x 2.28 = 4.5kA

 

[SirKit Breaker]

Useful Junk .

Determination of 3 - phase fault current .

Highest single phase value measured = 2.28kA
( 2.25kA , 2.28kA , 2.25kA )

By calculation : 2.28 x √3 = 3.95kA
An approximation can be done as ( 2 x ) the reading .. 2 x 2.28 = 4.5kA

True enough, but for the exam keep it simple and double the highest single phase reading as it errs on the side of caution.

Cheers...........Howard

 

[Knobhead]

This really should be back as a sticky.

 

[Marvo]

It's listed in the sticky that highlights the important threads.

 

[amberleaf]

Useful Junk .

Extracts

Electrical Enclosures Outdoors

The likelihood of water penetration must be carefully assessed

Presence of water . Etc

P/123 . Regulation 522.3.1
A wiring system shall be selected and erected so that no damage is caused by condensation or ingress of water during installation, use and maintenance.

P/123 . Regulation 522.3.2

 

[amberleaf]

sorry about that cut off

P/123 . Regulation 522.3.2
Where water may collect or condensation may form in a wiring system provision shall be made for its harmless escape through suitably located drainage points.

 

[amberleaf]

Extracts .

It is worth considering Section 710 in relation to veterinary surgeries if there are concerns over animal welfare during surgery

Veterinary practise

BS 7671 Regulation 411.3.3 sets out the requirements for additional protection to socket outlets for use indoors. There are exceptions depending upon the level of supervision, and also for socket outlets that are provided for a specific item of equipment - as opposed to those for general use.

If there are concerns over the welfare of animals in the event of a trip, then dedicated circuits for this equipment could be considered, ensuring that the outlet is identified to the equipment it has been designed to serve (exception (b) of 411.3.3.).

Any outlets intended for general purpose use by ordinary persons should be additionally protected at 30mA by an RCD, unless the use of them is effectively supervised. The question of supervision should be discussed with the practice management to establish whether any such supervision is achievable and sustainable.

The same discussion should also include any supervision required by Regulation 522.6.101 with reference to cables concealed in walls and partitions, as a consumer unit replacement is effectively an alteration as defined by BS 7671 and hence the requirements of 522.6.101 should be considered.

P/230 . Worth considering Section 710 in relation to veterinary surgeries if there are concerns over animal welfare during surgery
( Note 2 to Regulation 710.1 ).

 

[amberleaf]

Basics :
( Existing installation ) The full ( EIC Report ) documentation .
( New installation ) Safety certification

Firstly this one goes round the circuit , all the time
You have to ( prove ) that you are competent person , in the eyes of C&G

Firstly people need to get their heads around the difference between Initial verification & Periodic Inspection & Testing. They are 2 different jobs that have some common activities.

Inspection & Testing

Turning to Initial verification & Testing you need to have a look at chapter 61 of BS-7671:2011:. Have a look and see what tests are applicable to Initial verification ( Chapter 61 )

Turning to Periodic Inspection & Testing you need to have a look at chapter 62 of BS-7671:2011:. Have a look and see what tests are applicable to Periodic testing ( Chapter 62 )

P/16 . Extracts . Verification :
The responsibility for comparing inspection & test results with relevant criteria as required by Regulation 612.1. ... ( relevant criteria ) Testing