On 10/11/19 13:40, Martin Brown wrote:
On 10/11/2019 13:04, Jeff Layman wrote:
Last year we had a problem with our 5-year old Beko tripping the RCD
when it was turned on (NB it had been modified during a recall shortly
after we bought it). It only did it on that one day and has been fine
since.

A month ago it ran through its drying cycle with no problem, and beeped
that it had finished. We removed the dry washing, and took it away. When
we returned a couple of minutes later, we found the RCD had tripped.
This has occurred twice again - the dryer is fine working, but trips the
RCD as it cools down. Once cool, it seems ok and can be used again.

I have seen this sort of fault the other way around with failing kettles
where there is an initial RCD fail when used from cold but the thing
will then work for a good while after you have reset the breaker.

Eventually it fails completely and never recovers.

I'll have a look inside to see if there's anything obvious, but has
anyone heard of a fault which behaves this way?

My guess would be condensation getting somewhere that it can provide an
earth leakage path.

Yes, that could be it. But it would have to be pretty early on in the
circuitry, as it still trips when the on-off push switch is "out". I
guess it could just be a "false" physical break, and it's really an
electronic circuit break which still leaves some connection even after
switching off. It might be obvious when I have a look inside.

It may be time for a new drier, but I'm intrigued as to what this one is
doing.

Can you measure resistance (when unplugged) from live to earth and

That was one thing I was going to try, but I wondered if it might need a
decent voltage (although not quite up to Megger standard!) to see if
there was any breakdown.

--

Jeff