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Needing to meet mcb zs with ln loop.
Former Community Member
Where an rcd is relied on for fault protection due to high zs it has been suggested to me that the loop between live Conductors needs to be less than the mcb max zs. I can't find anything on this anywhere but he said he had this confirmed by an niceic assessor. Have I got it wrong ?
. . . this is not good for the wire, but not dangerous for an earthed person, because as soon as they touch the faulty part some current is diverted, L and N current is not equal, and the RCD kicks in. . .
It may do. You are of course assuming that the supply at the location of the RCD is high enough for its internal electronics to be powered. I am of course assuming it has an internal voltage connection rather than taking its power from the measurement CT.
. . . this is not good for the wire, but not dangerous for an earthed person, because as soon as they touch the faulty part some current is diverted, L and N current is not equal, and the RCD kicks in. . .
It may do. You are of course assuming that the supply at the location of the RCD is high enough for its internal electronics to be powered. I am of course assuming it has an internal voltage connection rather than taking its power from the measurement CT.
