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

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.

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  • Thought it could trip at 12kohm (at 240v) since 20ma is over half the rcd rating.

    True - you'd need 30mA for a "would trip", but anything over 15mA for a "might trip"  - so anything below about 15.3kΩ carries a risk.

        - Andy.

Reply
  • Thought it could trip at 12kohm (at 240v) since 20ma is over half the rcd rating.

    True - you'd need 30mA for a "would trip", but anything over 15mA for a "might trip"  - so anything below about 15.3kΩ carries a risk.

        - Andy.

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