Failed my LABC final inspection

[securespark]

I haven't got a copy of them to hand, but unless it's changed in the 17th edition, 33ms is a perfectly acceptable trip time (100% of rated tripping current should cause it to trip within 200ms, and if protecting against direct contact a test current of 150ma should cause it to trip within 40ms) - 33ms fits within both of these. These time requirements may have been tightened up in the 17th edition though - I'll check when I can get at my copy (but I'm sure someone will say sooner if that is the case)...

If the RCD is to 4293, then 200ms for 1x test. If to 61008, then 300ms.

In either case, the 5x test is 40ms max. If the RCD is of value >30mA, then 5x test is not required.

YES. Your LABC examiner should always test the RCD in isolation:

Switch off all outgoing MCB's and disconnect the outgoing neutral from the RCD or N bus, whichever is easier. Then switch the RCD on and test direct from the outgoing terminals.

Otherwise you cannot ensure an accurate reading.

Take today for example. I tested an RCD another spark said was faulty. It did indeed trip on the 1x test from a socket outlet, but when tested in isolation, the trip times were good, and the Ramp was 24mA, whereas the other spark said it was 16mA.