Ir test on bs 3036 wylex board

[Jabbajaws]

Hi all, l recently did a eicr on a fish and chip shop.

3 phases (only one phase in use by chip shop). Earth conductor is welded together to each phase by TN-S earthing system means.

When it came to the IR test, l tested the norm tests, L-E, L-N & N-E.

Bearing in mind that we are now supposed to do the IR test without disconnecting the conductors from the CU.

All L-E readings were ok (in the hundreds Mohms).
All L-N readings were ok (same)
All of my IR tests between N-E are exactly the same on the Wylex, due to the fact that the only place l can test TO (without disconnecting conductors) is between the Neutral busbar and the earth bar.

All readings on every circuit were 0.71Mohms, which is obviously far too low.

Can l just ask where im going wrong? I normally disconnect the conductors for an accurate reading but have been told not to by other sparkys, due to regs (which im unsure of the reg this covers).

Any advice or feedback anyone???


:uhoh2::uhoh2::uhoh2::uhoh2:

 

[Silly Sausage]

On a periodic, you only need to test between L&N to E.

I've probably misinterpreted your post, remember, N & E are essentially connected, so N to E would be zero.

 

[GT1]

Whoever is telling you that your not to disconnect conductors needs a kick up the arse.

Yes you "may" do a global test across bus bars and neutral bars etc etc... But ONLY as a time saver..!
ie if you do those three tests at the CU and all is well, then job done..!! (As far as IR testing is concerned.. )

However nothing precludes you testing individual circuits. It's a very occurrence that a global IR test comes good at first bite. They nearly always need splitting down further to see where the problem child is. !

Have you read this mysterious "reg"..??

 

[iamelectric]

where did you read that on a pir you only need to test between L&N to E ? i am not saying its untrue but i have never read this

 

[Silly Sausage]

GN3.

Periodics, you're just testing the install is safe, ie, no Exposed parts can be live.
A L to N fault would just result in a short circuit and the breaker would trip.

 

[Guitarist]

The recommendations are not to disconnect the cpc (in case you forget to reconnect it) when carrying out IR tests now, nothing to do with neutrals.

 

[telectrix]

which is silly if you think about it. if you forget to reconnect a N in the CU, then 1. that circuit will not work. 2. all the circuit cables ( except cpc) would be live. same reason that fuses in the neutral line were scrapped years ago.

 

[iamelectric]

cheers archy , table 3.4

 

[Jabbajaws]

Thanks to everyone that replied.

No Archy, l never read the reg. Its merely sparky talk between friends.

I must have mis-understood the people who have told me this or they have it wrong.

Thank you all. All feedback duly noted..

 

[terminator]

I think it was changed in 2008 - Reg 612-3-1

 

[Farmelectrics]

A global test ie Ln to earth tells me it's ok if readings are good to change old rewritable DBS to new 17th edition ones just done one yesterday