Surge Protected Socket Outlets

[uksel]

just having a scan through the examiners notes posted regarding the 2391

noticed on of the comments made was

'

"could not state the minimum test voltage to be used and the minimum acceptable value of insulation resistance when carrying out a insulation resistance test on a circuit containing surge protected socket-outlets"


I cant find specific reference to this anywhere, are they looking for test 2, IR to earth with Line & Neutral connected together??

or would they be asking for a soft test at 250v.


really looking for a page or regulation reference for confirmation if anybody has any insight?​

 

[Des 56]

Yes,I think they are making critisism of perhaps poor overall satisfactory answers to the problem set rather than a specific regs reference
It would be test 2 at 500v where the items could not be dis connected
Gn3 page 38 would probably be the nearest

 

[uksel]

well funnily enough, i'm having a look at the february exam paper (from which this examiner feedback was apparently given)

Q15. An insulation resistance test is to be carried out on a radial circuit supplying socket outlets that incorporate surge protective devices (SPD's). State the TWO procedures identified in BS7671 that permit the test to be carried out



now, that is the exact working of the question, so there are two main things to highlight here

1. there are aparrently two procedures for this specific example given
2. it specifically relates to references in BS7671 that 'permit' the tests to be carried out


i'm searching but not coming up with anything, yet in the eyes of C&G and the examiner, this is information that every candidate should know (it is also specifically highlighted in their own exam success book).

 

[JulianC]

From 612.3.2 I would say the two procedures are:

1) Test with the SPDs disconnected or, where it is not reasonably practicable to disconnect
2) Test at 250v dc, but still adhere to a minimum reading of 1Mohm

 

[bugsy]

I can only suggest this item is specifically covered in the swot sheets

 

[uksel]

good find julianc

having read that, i would 100% agree with

1. disconnect before carrying out the test
2. reduce test voltage to 250v but with a resistance value of at least 1 ohm


though it begs the question, would SPD's & similar have a resistance of greater than 1 Megaohm?

 

[Des 56]

Julian c

Thats a new one that I dont think was in the 16th
Good information Thanks