On 15/12/2012 16:35, Caecilius wrote:
On Sat, 15 Dec 2012 16:00:17 +0000 (UTC),
(Andrew Gabriel) wrote:

I've never found an RCD which failed by taking too long to trip.
Only those that are too sensitive, or don't trip at all.

That's interesting. Perhaps the leakage plug method is not too crude
after all.

My current 30ma RCD always trips at 16ma (15K resistor) and sometimes
trips at 11ma (22K resistor), so it looks like it trips somewhere
between these two values. I realise it should be somewhere between
15ma and 30ma, but I'd like to see something closer to 30 than 15.


I wouldn't mind betting that the leakage that's causing your trips is
coming from a single source. It may or may not be over 30ma, and it may
be highly intermittent, but finding that slightly duff appliance would
be a better bet than replacing the RCD for stopping the trips. A new RCD
may well be very nearly as sensitive as the one you have already.

If it was my system, I'd be trying to measure the actual leakage current
so I could go around plugging things in one-by-one, hoping to see a
significant increase at some point.

Since you don't seem to mind fiddling about a bit, you could temporarily
connect a multimeter to the current sensing coil and then characterise
the reading you get against your leakage plugs.

On the other hand, you could just replace your kettle. It always turns
out to be that in the end ;o)

Cheers,

Colin.