Earth/Neutral fault

[Daddy Boots]

Sparks fitting new fire-rated downlights in bathroom and the 2nd sparks instead of grabbing the new loop cable, he grabs the new cable to the shaver point and wonders why one of the downlights is permanently on !
So we sort that, and now when 2nd Sparks connects the new downlights and the old upstairs lighting circuit to the RCD it trips.
He's telling me I have a earth/neutral fault existing on the circuit cos it couldn't possibly be on the new stuff.
I have 12 ceiling roses across 2 floors. Where do I start to look for the earth/neutral fault ? Sparks 2 doesn't fill me with confidence. The CU was new in Jan 2007 , but I think only the ringmain was on RCD.

 

[thomo27]

I would ask the electrician to find the fault...for a fully competent electrician they will be able to narrow it down and find the cause..

 

[securespark]

Have you got two lighting circuits, one for upstairs lighting and the other for ground floor?

Has he installed a new CU which has one on one RCD and the other on the other? There may be a borrowed neutral....

Or has the RCD been OK and only tripped when the new wiring was connected?

Either way, he does not fill me with confidence, especially after connecting the DL to the wrong supply....

Ask him for his qualifications.

 

[Sherbertlion]

I'm surprised they didn't find the fault when they tested the circuit they were about to add on to.

 

[PrenticeBoyofDerry]

He's telling me I have a earth/neutral fault existing on the circuit cos it couldn't possibly be on the new stuff.

Has the electrician proved this or is it just bravado?

 

[Daddy Boots]

http://home2.btconnect.com/dublydublydubly/PhotoAlbums/album_1332184873
So upstairs lights were on 3rd breaker from the left, 4th is a spare for future.
Covers 2 upper floors into the eaves, so no loft. All worked fine. Sparks No1 ( subbed by builder) insists he won't sign it off without the new wiring being on an RCD which he says will have to go in a new box to the side on an RCD and quotes my builder 60 quid. He scarpers on a callout and leaves sparks No2 to carry on. So No2 gets the shaver cable, then he scarpers to get his daughter from school and when he returns he's wiring within the existing CU and saying I have the earth/neutral fault. So , where's this extra box No1 talked about, and are the lighting circuits on the left of the board on MCB's and not RCD protected ?
I've no doubt I'll end up paying extra fo rthis despite it being subbed by my builder.

 

[PrenticeBoyofDerry]

Easiest way to find out what is covered by RCD is to turn everything on, press the test button and see what goes off and what stays on.
If the board is split and the lights are not covered by RCD. I would suggest getting a siemens RCBO for the board but it's not a board I can honestly offer an opinion on, as it is a type, I have not worked on before and not sure of the availability of RCBO units for them. Others may!

 

[Daddy Boots]

It's a split board as only the ringmain went off, lights stayed on. I think Sparks No1 couldn't get a RCBO so advised another unit outside the CU.I didn't see Sparks No2 with anything, but have to assume from his comments he put the upstairs lighting onto an RCD of some sort which tripped. The circuit is now back on the MCB and working ok. We'll see what ocurrs when Sparks No1 deals with my builder.

 

[ericmark]

Neutral - earth faults and borrowed neutrals will only show up when a RCD is fitted. With a standard ceiling rose daisy chained system it's not too hard to drop the covers and test. However once someone removes the ceiling rose and starts to hide terminal blocks in the ceiling then tracing is a problem.

Borrowed neutrals are often associated with two way lighting where originally the lights were all on one protective device but on an up-grade someone has split the upper and lower floors using two protective devices failing to realise that the strappers on the two way lights were twin wire not triple. In which case switching on lights with one of the pair of switches will trip the RCD but with other one it will not so easy to work out what has happened.

As to who pays that's a hard one. Often quotes allow for things to go wrong and one would hope they would honour a quote. However where one finds that the existing building is faulty there of course has to be a limit to how much can be absorbed.

How ever interesting it may be to give advice is really pointless as clearly you have to rely on the tradesmen you have.

 

[PrenticeBoyofDerry]

Well it needs to be sorted out, as you have had new lights and I assume new cables for them fitted in bathroom, and these should now be protected by RCD/RCBO.
Like ericmark has mentioned about quoting and unforeseen events.
When quoting I also mention unforeseen circumstances.
But the electricians should have tested the existing circuit prior to connecting to it.
It would be interesting to know if the builder/electricians have actually proved their part of the circuit is 100% okay.
It would also be interesting to know if the RCD goes if the bathroom lights are left out of circuit.