Hi can anyone direct me to a site from which i can purchase a 100amp 100ma time delayed rcd with an enclosure (insulated plastic type) to put on a TT supply before the CU.

Many thanks
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Thanks, but i do not seem to be able to find one on tlc which states that it is a time delayed one. The only ones i can find just say 100ma RCD and no mention of time delayed ones.

Would it be acceptable to use RCBOs instead?. But i can not find these either.

The Setup is tt supply with split load board everything on the 30ma rcd side apart from 2 light circuits. Thus i need a 100 ma time delayed rcd rated at 100amp to use before CU. Or have thought about using 2 RCBOs for the 2 light circuits but they would need to rated for lights and fit a tenby board which currently has legrand mcbs in it.

Any one got any ideas?
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Yes seen them RCBOs but assumed they would not be suitable as i thought generally that all lighting circuits should go on a 6amp MCB or 5 amp old style fuse. And after looking at the prices of them RCBOs, i might as well try and find a 100ma time delayed RCD for the whole CU


On the subject of RCD's, I have one between my CU and Kitchen/Livingroom Ring Main Socket circuit.

When I switched OFF the B32 amp supply MCB (which is upstream of the RCD), to do an "R1 and R2 test", I was surprised that the RCD actually Tripped Out, the moment I connected my 16th edition tester, between the Earth and Phase Contacts, having placed a test link between the Earth and Red conductors in the consumer unit.

Has anyone encountered this, where the RCD trips, even though the Incoming Supply is OFF, during a course of an "R1 and R2 test"???
28 Mar 2004
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United Kingdom
an electromechanical rcd (which i belive most CU units are) will trip on an imbalance even without a source of extenal power

the DC sense rcds which are electronically operated have a functional earth (cream wire) to make sure they can still trip in the event of a lost neutral

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