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Low insulation resistance on remote hager rcbo board and effect on upstream devices.

hertzal123

Was asked to fit an extra skt to kitchen.Old 3036 cu so fit an enclosure with 40A rcd at side of cu.

Had tested IR of ring final earlier and found to be 0.03M.The low reading was traced to a detatched

garage with a 6way hager board spurred off the ring,comprising 6no rcbos with earth leads.The "fault"

as expected cleared when the leads were disconnected.My question is:had there been a greater number

of rcbos in the board or boards, so a lower ir,would the upstream 30ma rcd trip?

Thanks for any replies.

                                                   Hz

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    30K to ground - assuming at 500vdc, is not that unlikely from those designs of active RCD designed to get the power to trip from L-E if power from L-N is interrupted. I'd be wary of doing that insulation test sustained, but it does not sound like real fault.

    And yes if you had enough of them to draw a significant chunk of 30mA then you could not have an upstream RCD of that rating. (and 24K is perhaps 10mA RMS so you are certainly well on the way to eating into the trip reserve.)
    Mike

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  • 0

    30K to ground - assuming at 500vdc, is not that unlikely from those designs of active RCD designed to get the power to trip from L-E if power from L-N is interrupted. I'd be wary of doing that insulation test sustained, but it does not sound like real fault.

    And yes if you had enough of them to draw a significant chunk of 30mA then you could not have an upstream RCD of that rating. (and 24K is perhaps 10mA RMS so you are certainly well on the way to eating into the trip reserve.)
    Mike

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