RCD test button ineffective

[Softus]

the test button has no reliance on an earth.

Er, to coin a phrase, keep up John!

might be the test button is faulty, might be the RCD is jammed. they do that sometimes, especially if not tested for a year or more (though your one sounds quite new)

I'll bear this advice in mind for the next time, but with this one it was important that I didn't delve further.
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Edit: Oh, Adam_151 already covered it

Oh b*gger - you spotted it before I did - bah!

 

[JohnD]

Thanks ricicle.

And I realise I posted "30ms" whereas I meant "30mA".

Oddly enough, they do tend to trip in about 30mS at 30mA.