I am converting a downstairs shower room into a utility room. I've removed the shower and I now want to install some sockets in the room. The existing electric shower circuit uses 10mm cable with a 45amp MCB. Can I use the existing circuit and convert it to a radial circuit for 13amp sockets, and can i use 2.5mm cable for the rest of the circuit?
Thanks
Yes. You must swap the 45A MCB with a 32A MCB.
It is very sensible to use the existing 10mm circuit, as it will have low voltage drop on a circuit expected to take heavy loading. It will prevent the overloading of an existing ring and minimise disruption to decoration.
No, you must use at least 4mm cable for the rest, and possibly (but probably not) 6mm. 6mm would be a pain to work with for socket circuits.
If you use 2.5mm, the MCB must be changed for a 20A MCB, which is insufficient to power the expected loads of a utility room.
Christian.
Surely it's possible to use 2.5 and a 32 amp breaker if he uses the 10mm cable as a supply to a ring as opposed to a radial?
Richard.
That's what I've done many times in the past. ..
SJW A.C.S. Ltd.
I don't see why not. However, it would be a slightly unusual layout, which may confuse lesser electricians in the future. I suppose you could call it a lasso circuit...
Christian.
Personally I call it a pain in the a**e circuit but it's how my '70s semi is wired - Large cable from CU to underfloor jointbox then ringed round the sockets. Figure the sparky got a good deal on the large size cable or was too idle to pull in the extra leg to the board. Richard.
I could see that it has advantages when wiring a tall house. Especially with current standards as to the number of sockets to install, a 4 storey house with consumer unit on ground floor could have earth loop impdedence/voltage drop issues limiting the cable lengths. Running the ring after a length of
10mm could seriously reduce the impact of the initial trunk part of the circuit on the available length.Christian.
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