Connecting a 100ma RCD for Ground Source Heat Pump

Discussion in 'Engineers' Talk' started by dave longster, Sep 13, 2017.

  1. dave longster

    dave longster New Member

    I would really appreciate some advice please, so that I can order the necessary parts and instruct my Electrician accordingly.

    I am installing a Ground Source Heat Pump which requires a supply using a 100ma RCD and 40amp C rated MCB. The instructions say this is to avoid nuisance tripping and the 100ma RCD is to provide protection against fire (BS7671 17th Edition).

    This is part of a new build conversion, so the starting point is a new BG metal clad twin 30ma RCD unit, which also allows for unprotected outways or RCBOs. This is fitted and supplies the house circuits.

    There is not much room in the cupboard to split the incoming meter tails, and I wondered whether we could use a spare unprotected fuseway with the 40amp C rated MCB into a separate enclosure and through the 100ma RCD to the heat pump, or is there an easier way ?

    With many thanks.
  2. kiaora

    kiaora Active Member

    ok i'll reply, seems you've had lots of views and no replies?
    it's the use of the words,
    " instruct my electrician,"
    and then ask advice?

  3. Dr Bodgit

    Dr Bodgit Well-Known Member

    Not sure about your setup exactly, when you say "starting point is a new BG metal clad twin 30ma RCD unit", is there not a 100A isolator? Without it I don't see how you can get a spare unprotected "fuseway".

    What consumer unit do you have? Assuming its a split RCD unit but allows for one or two non-RCD protected MCBs to be added, then I'd fit the C rated 40A MCB there (non RCD protected), then through the 100ma RCD to the heat pump.

    Or instead, ask your electrician as he's going to be signing off the design, installation and testing of said circuit...

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