Date   : Tue, 08 Sep 2009 09:29:42 +0100
From   : rs423@... (Mick Champion)
Subject: Leccy @ Acorn World '09

>
>> I agree and think radials make safer circuits. With a ring, we rely on
>> the two ends to be continuous. How would you know if they are not? You'd
>>     
>  
>   
Jonathan Graham Harston wrote:
> Competant installation and testing. I can do you a whole-house
> installation test and certification for 50 quid [plus travel! ;)]
>   
Why sir, you sell yourself short. That is a bargain and that's the 
truth. :-)  Normally anything that involves a certificate costs an arm 
and a leg, plus a kidney sometimes. I wouldn't take you up on it though 
as for your ?50+, it would take you half a day to get here to South 
London :-) . I also rent so while I have fully re-wired 3 houses on a 
like for like basis (excluding putting that nail through live wire and 
painting over it, or  twisting together lighting circuit wires and 
wrapping them in selotape!), I wouldn't touch this place. The people the 
housing association employ to do such works are pretty useless though. I 
expect they go for the lowest bidder and the biggest kidder. When adding 
central heating 4 years ago, they decided to replace all the single 
sockets with doubles by using surface double boxes that screw into 
single sub surface ones. Because none of the original cable was not long 
enough, every double socket is now a spur of the ring. They crimped 
every last one of them to extend the cable.




>  
>   
>> properly, or a rat needs a quick chew. Your breaker will still not trip
>> until 32 amps have been exceeded, but now all your power comes from one
>>     
>  
> If only one line has been chewed, an RCD/MCB would detect the
> imbalance between lines, and trip. You can get dual RCD/MCBs (or do
> it manually) where each end of the ring is connected into its own
> connection to guard against the ring becomming two radials, but in
> almost all installations that's unneccessary over-engineering.
>   
I've only ever worked with single output MCBs. It sounds like a good 
plan though rather than over-engineering. Detecting how much power goes 
through each cable on a ring has got to be a good thing hasn't it?




Mick