On Nov 7, 12:12*am, John Rumm wrote:
On 06/11/2010 15:46, Dave Osborne wrote:

Yes, you should definitely suspect the RCD. Also, you may have an
insulation fault that is pushing the RCD very close to its trip level.

This means that the slightest imbalance or increase in humidity will set
it off. The vacuum cleaner sets it off because of the inrush on starting
(John Rumm might be along later to explain why).

Covered he

http://wiki.diyfaq.org.uk/index.php?...nsitising_RCDs

Also, get your installation checked out at some point to see if you can
find where the leakage current is coming from.

Following some of the tests described here can find many causes:

http://wiki.diyfaq.org.uk/index.php?...cate_the_cause....

--
Hi everyone and thanks for the input so far.

This morning I connected the vacuum cleaner directly up to the RCD in
the consumer unit. Nothing else connected. Immediately I turned on the
vacuum cleaner, the RCD tripped. So, I have reproduced the fault
having isolated the wiring.

Bearing in mind the above, and the fact that I have seemingly random
trips occuring on all RCD protected circuits, at inexplicable times
(i.e. no load), I am inclined to suspect the RCD as being over-
sensitive, and am minded to buy a replacement.

I am pretty sure I am right, that a vacuum cleaner, which presents no
path to earth at all, and hence no means of providing a leakage
current, should not under any circumstances trip the RCD. That's
correct isn't it?

Luke