[Gllug] OT: Mains electricity colour coding.

[Simon Wilcox]

On 26/10/2010 11:44, Chris Bell wrote:
> On Tue 26 Oct, James Courtier-Dutton wrote:
>
>> In the UK, certain faults cause the central fuse box to click off, but
>> it can be any device on the ring main that caused it, making location
>> of the fault more difficult.
>>
>     I assume you mean the Residual Current Circuit Breaker RCCB, otherwise
> known as the Earth Leakage Circuit Breaker ELCB, which trips if the total
> sum of live and neutral return current exceeds a very low maximum value.
> This could be due to a number of faults, but the tripping current is set to
> about the value that the human body can survive during accidental contact.

It's an excellent protection but the OP has a good point, our ring main 
designs can make it tricky to track down faults. A star arrangement 
would make it much simpler to isolate a fault, albeit at the cost of a 
lot more wiring and therefore potential places for faults to occur.

I encountered a wiring fault a while ago that took ages to track down, 
turned out to be poorly installed wiring in the kitchen that wasn't 
protected in the floor screed. Concrete eats PVC cable insulation. Odd 
faults start showing up.

We moved before it was properly fixed but I understand the landlord had 
to rip out the kitchen ring main and reinstall it completely to fix the 
problem.

To be fair, that was probably easier with a ring than with a star 
arrangement if it had been equally poorly installed but the ring meant 
it took a long time to isolate the true cause of the problem.

Simon.
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