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Choosing best rating circuit breaker to protect 16A commando socket

Alan B

I was installing a 16A commando socket today which I protected with a 30mA rcd followed by a 16A MCB.

Other breakers nearby were not heavily loaded so derating was not an issue. But if I say wanted to connect to a heavily loaded consumer unit my initial reaction would be to put in something like a 20A breaker and suitable cable.
But then I thought the socket and plugs are not fused and I have no control over the cable connected to the socket. Therefore do I have to assume I am protecting a cable that is only rated at 16A and never use a breaker with a rating that exceeds this?

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    A single 16 amp ceeform socket outlet should be connected to an MCB not exceeding 16 amps. Although LESS than 16 amps is permitted, I would consider this to be poor practice in most situations, an ordinary user might expect to be able to use a full 16 amps.

    Two or more 16 amp ceeform outlets may be protected by a 20 amp MCB.

    Any appliance fitted with a  16 amp plug should be suitable for connection to a 20 amp circuit. The flexible cord fitted to the appliance may be sized according to the load, but not less than 0.75mm. Experience has shown that 0.75mm flex can be protected against short circuit by a 20 amp MCB. Overload protection should be by design of the appliance.

  • 0 in reply to broadgage
    broadgage said:
    A single 16 amp ceeform socket outlet should be connected to an MCB not exceeding 16 amps.

    Why ... what is the difference between a single 16 A socket-outlet supplied by a 20 A circuit-breaker, and a circuit with two 16 A socket-outlets supplied by a 20 A circuit-breaker, in which one of the socket-outlets is not in use, or is pulling additional load (causing heating behind the terminals of an upstream socket-outlet that might be fully loaded) ?

    The 20 A may be preferable because of inrush or starting currents in some cases?

    Similarly, there is nothing to prevent a 30 A ring-final circuit with only one single or double 13 A BS 1363 socket-outlet, or a radial from a 16 A or 20 A circuit-breaker with a 13 A single or double socket-outlet ?

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  • 0 in reply to broadgage
    broadgage said:
    A single 16 amp ceeform socket outlet should be connected to an MCB not exceeding 16 amps.

    Why ... what is the difference between a single 16 A socket-outlet supplied by a 20 A circuit-breaker, and a circuit with two 16 A socket-outlets supplied by a 20 A circuit-breaker, in which one of the socket-outlets is not in use, or is pulling additional load (causing heating behind the terminals of an upstream socket-outlet that might be fully loaded) ?

    The 20 A may be preferable because of inrush or starting currents in some cases?

    Similarly, there is nothing to prevent a 30 A ring-final circuit with only one single or double 13 A BS 1363 socket-outlet, or a radial from a 16 A or 20 A circuit-breaker with a 13 A single or double socket-outlet ?

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