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Three Phase RCD & MCB Wiring?

Nano Brewery
Please could somebody advise on the most cost effective procedure of wiring up RCDs & MCBs on a DIN Rail for independent circuit protection.  Tried Googling to no joy.  Plenty of Single Phase advice, images, videos.  If using 4 Pole MCBs & RCDs, would I be correct in assuming that similar to single phase, it's just a case of Busbar-ing the MCB Lives to the RCD Lives and taking the RCD to Neutral Bar?


Have seen diagrams (like below) where the Incoming L1, L2, L3 get split to separate DP MCBs, RCDs and SP MCBs for each phase.  Seems like a bit of a faff and a pricey option (3x DP MCBs + 3x RCDs + 3x SP MCBs) per circuit.


I have 3x Three Phase Circuits (13A, 40A, 48A) that I wish to protect independently with RCDs.


Thanks in advance!  Dan.

ddbd56232f43509726e961c7a00902b6-huge-image-20210208123140-1.png
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  • 0
    What you draw is OK for  a system where 3 phase comes in, but all loads are single phase.   In effect you have drawn 3 single phase consumer units - and that is one  legitimate approach, if your loads are like that.

    3 phase boards for 3 phase loads have a 3 pattern L1 L2 L3  bus bar so every tooth is only connected to the ones multiples of 3 places along.


    . And just to catch you, L and N  (pitch of two) and 3 phase and neutral (pitch of 4 ) busbar is also manufactured but rarer.


    an RCD for a 3 phase load must carry all the phases, and neutral if there is one, so that in normal use, it sees no net current.


    I suggest you contact the helplines of  one of the makers of commercial consumer units (Hagar, Eaton etc) to advise you about what they make, as there are a lot of options, and it is very easy to specify the wrong thing, the advice is free, so long as you do not string them along..

    Are the loads in your drawing correct, or just nice numbers ? Thinking diversity.

    M.

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  • 0
    What you draw is OK for  a system where 3 phase comes in, but all loads are single phase.   In effect you have drawn 3 single phase consumer units - and that is one  legitimate approach, if your loads are like that.

    3 phase boards for 3 phase loads have a 3 pattern L1 L2 L3  bus bar so every tooth is only connected to the ones multiples of 3 places along.


    . And just to catch you, L and N  (pitch of two) and 3 phase and neutral (pitch of 4 ) busbar is also manufactured but rarer.


    an RCD for a 3 phase load must carry all the phases, and neutral if there is one, so that in normal use, it sees no net current.


    I suggest you contact the helplines of  one of the makers of commercial consumer units (Hagar, Eaton etc) to advise you about what they make, as there are a lot of options, and it is very easy to specify the wrong thing, the advice is free, so long as you do not string them along..

    Are the loads in your drawing correct, or just nice numbers ? Thinking diversity.

    M.

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