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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 ?
I’m reading the sales blurb for the Megger MFT1741 and it has this feature:
NEW: Type B loop test option for performing 3-wire non-trip loop tests on circuits containing 30mA Type B RCD or RCBOs
So what the issue with using a standard loop tester in an installation protected by a Type B 30 mA RCD device?
Andy
MFT1731 tests Type B RCDs. It is necessary, however, to be careful that the test suits the MCB. If you forget to change back to type AC, you may wonder why your checkbox has started to give different values. ?
I’m reading the sales blurb for the Megger MFT1741 and it has this feature:
NEW: Type B loop test option for performing 3-wire non-trip loop tests on circuits containing 30mA Type B RCD or RCBOs
So what the issue with using a standard loop tester in an installation protected by a Type B 30 mA RCD device?
Andy
MFT1731 tests Type B RCDs. It is necessary, however, to be careful that the test suits the MCB. If you forget to change back to type AC, you may wonder why your checkbox has started to give different values. ?
