6mm becomes 2.5mm

[South Spark]

I'm changing a consumer unit- Circuitry in the house is bizarre - (e.g three double sockets in the kitchen each one on a different circuit , lighting in second extension on same circuit as the rest of the downstairs lighting but earthed via one of the ring mains)


One circuit was on a 40A breaker on the original CU - it's 6mm twin and earth. In fact it only supplies two sockets and a lighting spur. Took off the socket fronts and of course it's 2.5mm, wired as a radial.

I'm guessing that the cooker used to be electric (now gas) and these sockets are spurred off it. Obviously I've no idea where the junction might be. IR and R1/R2 check out OK. - I was going to put the whole circuit on a 16A breaker as a radial.

Is that kosher?

 

[T&Earth]

Hi South Spark

That sounds ok to me as long as its 2.5mm could use 20A mcb, but using 16A would be just as well.#
T&E

 

[nickblake]

As T and earth has said just note the cable size change on the cert and DB just in case some one increases the MCB to 32 amps

 

[ian.settle1]

As T and earth has said just note the cable size change on the cert and DB just in case some one increases the MCB to 32 amps

If it's a radial it should be de-rated to a 20A for 2.5mm

 

[nickblake]

Yes i know mate begining of my post i put as " T and earth" then put lable dist board just in case its increased to 32 amps , meaning that it changes from 6mm to 2.5 as tandearth pointed out

 

[oldtimer]

I had a problem like this there was a 6mm getting fed by a 30 fuse with a twin socket fitted at the other end so why was this well the customer had a gas cooker so done away with the cooker switch and replaced it with a twin socket so when I put a new board in i downgraded the fuse from 30 amps to a 16 amp circuit breaker

 

[South Spark]

Thanks for all that - easy in the end. Shame about the next eight hours looking for the phase/neutral short in the upstairs lights.