James asks this question, which concerns the possible choice of a 16A MCB protecting a radial circuit serving’ sockets used by cleaners. It has been answered by SELECT (Theme – Distribution Equipment including Cable Management):
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Question: A query has been raised as to whether one can use a 16A MCB on a radial circuit serving cleaners’ sockets.
If you were to use Appendix 15 of BS 7671: 2008 (2011), the options given are:
- 20A overcurrent protection device (any type) - All live conductors can be wired in 2.5mm2; however you are restricted to serving a floor area of 50mm2.
- 30/32A overcurrent protection device (HBC fuse or circuit breaker) - All live conductors can be wired in 4mm2; however you are restricted to serving a floor area of 75mm2.
There seems to be a lot of discussion online as to whether 16A radial circuits are acceptable. However, as far as I can determine from the regulations, if you were to use a 16A overcurrent protection device, you would have to treat it as a fixed load limiting the circuit to a single socket (13A).
Have you come across this query before, or do you have any further guidance you could share?
Answer: It is acceptable to install a number of sockets on a radial circuit using 2.5 mm cables protected by a 16A circuit breaker - provided that the expected connected load does not exceed 16A.
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