An elecrician installed a second condumer unit for me a few years ago, with 3 sockets coming off it..
He also put in a new earth for it, and said it should be at least a yard from the existing earth, maybe so the two RCDs wouldnt interfere with each other.
But shouldnt earth bonding be attached to both, and to the water pipes, so both earths should be connected to each other.
What's going on, I dont understand it..
[g]
Find a sparks who knows what they are talking about. Modern RCDs don't care a tinkers cuss about the precense or otherwise of the CPC. Out of the ark voltage operated devices did but you won't find many of those about these days.
Common sense says that all the equipotential bonding and CPCs should be connected back to the main earth point. But earthing and equipotential bonding are not quite the same thing and there are variations depending on your supply type.
equipotential
depending on
Sounds like a TT supply with two earth rods perhaps?
AWEM
TT2? :)
NT
I still dont understand why the electricians wanted to put the new earth rod at leat a yard from the old one, when they are going to be connected by the bonding conductors attached to the water pipes etc.
[g]snipped-for-privacy@care2.com wrote:
Even with an ELCB install it would be the wrong thing to do. Right thing would be to take feed for CU2 from after the ELCB.
And since the terms are French, it would probably be 'TTB', bisectee. Or BBF, fou.
NT
I presume we are talking earth spikes here on a TT installation?
Was your existing install also TT?
This is true. It is better to not place a new rod within the resistance area of the other one. The actual separation distance will vary with soil conditions - better conducting soils requiring more separation. One rule of thumb suggests that the spacing should be at last as much as the length of each rod (typically 1.2m).
Was the "maybe so the two RCDs wouldn't interfere with each other" your assumption or something he said?
Yes, both should be connected together anyway usually at the main earth terminal assuming the purpose of the exercise was to lower the electrode resistance.
Yes I think so - there are 2 fat wires coming in.6
I think it was my assumption
Good, I will connect the two and renew the bonding to the water pipes.
The purpose was to put in new wires for electric heaters etc without disturbing the ancient wiring system to lights etc whilst I work out what wire is what and replace various bits and pieces and learn more about wiring regulations etc...
[g]
There are some handy pictures in this document that should let you work out exactly what you have:
Ah, ok. Chances are he wither installed a new rod to lower the overall resistance path to earth, or the existing install was looking rather fragile and he did not want to mess with its wiring at all - even to test the original electrode. (to test it you need to get it in isolation with the EQ bonds disconnected)
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