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seanmckinney seanmckinney
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  • Posted on: 26/8/2006 13:20
An odd UK RCD problem, I am not sure if the same things would apply elsewhere #1
I'll keep this brief, I have just fitted an RCD protected consumer unit for a friend. Yes I am aware of the new regs and the need for a minor works certificate and that is in hand.

When the CU was powered up the RCD tripped when ANY of the protected ciruits was energised and load baring, I finally found it was a faulty neutral on one of the protected circuits. So just in case any one runs their pond off an RCD'd circuit, bare this symptom and cause in mind.

The cause being that since all the neutrals in the RCD'd circuits are permanently connected to a common neutral bus bar and that bus bar passes the neutral current back through the RCD, the faulty neutral was dumping some of the neutral current in the bus bar to earth.

Goldy Goldy
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  • Posted on: 26/8/2006 19:30
Re: An odd UK RCD problem, I am not sure if the same things would apply elsewhere #2
Gather the reason you mentioned this Sean is as a warning to others that may have similar problems
seanmckinney seanmckinney
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  • Posted on: 26/8/2006 22:56
Re: An odd UK RCD problem, I am not sure if the same things would apply elsewhere #3
Yep, I gather that a lot of 'modern' homes or 'recently' rewired homes would have rcd protected circuits in the consumer unit and I for one hadn't considered the repercussions of a fault to earth from the neutral on the RCD protected circuits. It's blindingly obvious once you think about it or in hindsight and maybe I was just being stupid not to have thought of it but if the thread saves someone else a load of hassle ..........
burkey burkey
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  • Posted on: 27/8/2006 0:32
Re: An odd UK RCD problem, I am not sure if the same things would apply elsewhere #4
oh noes electronics please explain this in a dumbass form for my benefit.
seanmckinney seanmckinney
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  • Posted on: 27/8/2006 10:54
Re: An odd UK RCD problem, I am not sure if the same things would apply elsewhere #5
if its the "elsewhere" bit you are asking about this board can be read by anyone anywhere in the world. Names for conductors or their function vary from country to country and wiring systems also vary so the above post is applicable to the UK.

An RCD is a safety device which compares the size of the currents flowing in the live and neutral circuits. The size of these currents, Amps, should be identical, if they are not there is something wrong, some electricity is going where it shouldnt. An RCD is designed to trip if the difference exceeds a certain amount.
worwood worwood
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  • Posted on: 27/8/2006 13:43
Re: An odd UK RCD problem, I am not sure if the same things would apply elsewhere #6
correct me if i'm wrong but an RCD is also known as a circuit breaker, right?
seanmckinney seanmckinney
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  • Posted on: 27/8/2006 14:35
Re: An odd UK RCD problem, I am not sure if the same things would apply elsewhere #7
Whilst you are correct that an RCD breaks a circuit, I dont know if the term "circuit breaker" is the one that would be used. The primary if not the only function of the RCD in that consumer unit is to cut the power to the circuits it covers if it detects a significant difference between the currents in the live and neutral 'wires' flowing through it

I think "circuit breaker" would be used when talking about a device the breaks the circuit when there is an overload ie too much current, so it is something like a fuse or the modern resettable quivalent of a fuse which in the UK I think is known as an MCB and I think these generally only break the live so that the neutral was still connected.
The RCD in that consumer unit broke/breaks live and neutral and "isolates" everything it covers from the mains. It was also rated at 63A but I dont know if it will trip if the current through it exceeds 63A or just suffer damage, I dont want to find out.


I dont know if plug-into-socket RCD.s isolate what the cover
Goldy Goldy
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  • Posted on: 27/8/2006 14:47
Re: An odd UK RCD problem, I am not sure if the same things would apply elsewhere #8
Quote:

worwood wrote:
correct me if i'm wrong but an RCD is also known as a circuit breaker, right?


No I believe they are differents, also the wiring maybe slightly different here than where Sean is "I have been kindly informed by my husband" but would take to long to type it all sorry
seanmckinney seanmckinney
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  • Posted on: 27/8/2006 17:03
Re: An odd UK RCD problem, I am not sure if the same things would apply elsewhere #9
If worwood is from London UK his wiring should be the same as here unless London is different from the rest of the UK
Goldy Goldy
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  • Posted on: 27/8/2006 17:24
Re: An odd UK RCD problem, I am not sure if the same things would apply elsewhere #10
Really although the rates have changed over the years I hear anyway will leave you guys to sort out the ins and outs ok