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Sub main and TT

Grumpy
I am dismayed that I have to ask but it is so long since I worked in a TT area that I am doubting myself.

I'm running an SWA submain to an outbuilding so instead of the usual switch fuse should I be using a 100mA S RCCB and a 63A mcb?

The armoured passing directly through the outside doesn't necessitate a 30mA RCD does it (as I have been so advised)

Apologies and thanks.

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  • 0
    I'd too keep the fuse rather than an MCB for the submain - otherwise you'd likely loose discrimination with downstream MCBs/RCBOs on L-N faults.

      - Andy.
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  • 0
    I'd too keep the fuse rather than an MCB for the submain - otherwise you'd likely loose discrimination with downstream MCBs/RCBOs on L-N faults.

      - Andy.
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