Opinion Please!

[securespark]

You are working at a house changing an accessory.

There is a "17th Ed." split-load boad.

You test both RCD's. Both fail repeatedly.

How do you treat the situation?

 

[riveralt]

More info needed:
When you say fail - does that mean they both trip when a circuit is energised?
Or do you mean that they fail during a ramp test?
Or do you mean they fail the mechanical test?

 

[securespark]

Both fail an auto test.

The test button works on both.

 

[ericmark]

You must inform the owners and occupiers both verbally and in writing the latter could be the installation certificate that's clear.

As to commissioning the accessory that's really down to common sense. Clearly if that accessory was a shower then don't commission until fixed, but a shaver socket would again clearly not be more dangerous because the RCD does not work and it could therefore be commissioned.

The same considerations as to the fault. With a TT system this is very serous but with a TN-C-S system we have run without RCD for many years without problem.

 

[ericmark]

After last post I see the built in test button works. I have had this where earth was incorrectly installed in fact someone had swapped earth an neutral in the consumer unit then left earth disconnected.
Clearly more dangerous that the RCD simply not working.
There is only one answer. Further investigation.
I do see the problem with charging for work you have not quoted for and I would want to get go ahead from the owner before I spend too much time working out why they don't trip.

 

[securespark]

Yeah, I should have been more clear about the system type.

It was TN-S.

I changed the RCD's and they were both faulty - no more no less.

Would you condider it a danger to leave the installation without wqorking RCD's?

 

[ericmark]

I have been surprised by some of the advice given in the ESC best practice guide but I think we really still have to in the main follow their recommendations. It has changed when we used 1, 2, 3, and 4 their guide said where the RCD protected items in special locations it was code 1 but with the C1, C2, and C3 this was changed and in special locations it's C2 and in non special just code C3.

So if for example the RCD supplied a socket which is likely to be used outside or in a bathroom then C2. Other wise it's only a C3.

I do like the way in which only really dangerous items are coded with C1 as it was all too common to see so many items coded with coded 1 that the owners did not always correct the most dangerous first but would do cheapest first.

Unless there were special circumstances like the house being used for child minding I would not really worry about non working RCD's and would be happy just to inform and note in certificates. May be my age but worked for years without them so can't really see too much of a problem.

 

[securespark]

Thanks eric.

I have been informed that an installation designed with RCD's is dangerous if those RCD's fail and all efforts should be made to replace the RCD's before re-energising.

 

[ban-all-sheds]

I have been informed that an installation designed with RCD's is dangerous if those RCD's fail.

If you're relying on them to get round high loop impedances, yes.

Otherwise a circuit on an RCD because it has buried cables is no more dangerous with a faulty RCD than the same circuit would have been 5 years ago when it wasn't on an RCD.

 

[securespark]

That is my opinion too.