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Rcd discrimination

NGUACE
Any Information greatly appreciated.


Each outdoor socket has to be RCD protected, so if you have a junction box supplying more than one outdoor 30ma socket, how do you achieve RCD discrimination all the way back. I have an older C/U and the rcd on it is also 30ma?


A spur from internal plug to fused switch outside, which then feeds multiple outdoor sockets?


this is just a scenario I am trying to figure out.


thanks for anyone’s time.


Andy
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  • 0
    Like OMS says. I am also a "Frontender" there`s a few of us here and quite a lot in the UK methinks. It was quite "normal" a while back and for quite a long time to have one mainswitch RCD feeding all MCBs for an installation. In an otherwise decent set up nuisance trips do happen but not regularly. The main thing about RCDs is "are they working correctly?" regular testing to check and regular tripping to keep the mechanism mechanically able to act are important to me. Some statistics suggest 7% failure rate (Note - failure includes those that trip but outside the stated standard), math theory would suggest therefore 0.49% failure might be acheived by two cascading RCDs. I`m sure that this figure would seldom be case though. Probably somewhere in between. Some of us come from an age before RCDs and relied soley on a rewireable fuse . I do not remember the council having to clear away piles of corpses each evening.
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  • 0
    Like OMS says. I am also a "Frontender" there`s a few of us here and quite a lot in the UK methinks. It was quite "normal" a while back and for quite a long time to have one mainswitch RCD feeding all MCBs for an installation. In an otherwise decent set up nuisance trips do happen but not regularly. The main thing about RCDs is "are they working correctly?" regular testing to check and regular tripping to keep the mechanism mechanically able to act are important to me. Some statistics suggest 7% failure rate (Note - failure includes those that trip but outside the stated standard), math theory would suggest therefore 0.49% failure might be acheived by two cascading RCDs. I`m sure that this figure would seldom be case though. Probably somewhere in between. Some of us come from an age before RCDs and relied soley on a rewireable fuse . I do not remember the council having to clear away piles of corpses each evening.
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