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3 Phase Inverter trips RCD but only when switched off

Discussion in 'Electrics UK' started by zebedee2001, 28 May 2021.

  1. zebedee2001

    zebedee2001

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    Howdy Folks...

    Slightly oddball fault. I've had a 3 phase inverter for some time but never got round to fitting it, lent it to a friend as his went wrong, he used it & all was fine. He gave it back to me the other week & I decided to fitted it this week to my garage.

    I have wired it in to its own MCB in the consumer unit in my garage. I have fitted a double pole switch in line with it (to aid isolation). The inverter switches on fine & runs OK, however if I switch off the inverter by the double pole switch it trips the RCD in the consumer unit. I can reset the RCD & all is fine. If I switch it off via the MCB it doesn't trip the RCD. The inverter runs on for a while with no load when the power is isolated.

    I don't get how double pole isolation causes the RCD to trip but single pole isolation doesn't.

    Thoughts please!
     
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  3. JohnW2

    JohnW2

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    Definitely odd, but I seem to recall that we heard here of something similar in the fairly distant past.

    It's not, in itself, an obvious explanation of how/why it could result in an RCD tripping, but one thing DP switching can possibly do that SP cannot do is to break the neutral before breaking the l line - which is perhaps something to ponder.

    Kind Regards, John
     
  4. securespark

    securespark

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    I posted the following in 2004...
     
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    DIYnot Local

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