2 RADIAL CIRCUITS ACTING AS ONE!

[Whofan]

The sparks who wired our kitchen extension and put in a new consumer unit says we have 2 radial circuits downstairs - 1 for the lounge & kitchen; 1 for the 'study' which he connected to 2 MCBs in the unit. I now wish to extend the 'study' circuit out into our newly finished conservatory. When I tried to isolate the circuit today I had to switch off BOTH MCBs at the unit (each one on its own had no effect) and, of course, both circuits went off. When I switched ONE back on, both circuits came back on! I don't understand!

 

[Aragorn84]

Sounds like they arent radials, but two legs of a ring main.

Either that or something is bridging the two radials together at some point along their path.

 

[Steve]

I do understand. What you appear to have is a ring final, with both ends wired into different MCBs. This is VERY DANGEROUS and I strongly advise you to turn off at least one MCB for this circuit until a proper electrician (not kitchen fitter / builder) can come to rectify this. What rating are the MCBs?

Did you get a certificate for the wiring in the extension?

 

[Whofan]

Thanks for the replies. We are of the opinion that it is something bridging the radials since I believe it has behaved as 2 radials in the past. How do we find out where and what is the problem? I have, nonetheless, ensured that one of the MCBs is switched off - they are 20a - and I have tried to contact the electrician today but unseccessfully so far. He is a 'proper' electrician and he has not yet signed off the work in the kitchen because there is a mass of work, all of which he will certificate at the same time.

 

[Chri5]

When I tried to isolate the circuit today I had to switch off BOTH MCBs at the unit (each one on its own had no effect) and, of course, both circuits went off. When I switched ONE back on, both circuits came back on! I don't understand!

I don't understand why your attempting DIY on the home electrics when you have a spark working for you?

It's deffo a cock up, what you need to decide and pass on to your spark is wheteher you wish to have 1 x ring at 32A or 2 x radials at 20A. The decision will have to be based on load existing and near future for each circuit.

PS If the spark has joined the radials over 2 x MCB I'd be worried about his 'skill' set/

 

[Whofan]

Thanks again. I've just managed to speak to the electrician who will be round tomorrow. Will report what he has to say in light of all these comments.