On Sat, 19 Nov 2016 02:49:57 +0000, John Rumm
wrote:

On 18/11/2016 12:02, Jack Lawson wrote:


Earlier this week I bought from Homebase a mitre saw:
http://www.homebase.co.uk/en/homebas...s-2125u-389395

I had read reviews and seemed to fit my needs perfectly.
Got it home - and tested it. I found that when I started the saw, it tripped
my RCD on the supply. Tested it further - sometimes it tripped - sometimes
not. This was on initial start-up with no load.
Took it back - got a replacement.

Is it even earthed, or is it double insulated?

The new one is just the same. About 1 in 10 of start-ups the RCD will trip.
The saw seems perfect for my needs - very accurate mitres and 90 degree cuts
are spot on - I think I will live with what for me is a minor problem - but
thought I'd just share.

This sounds more like a "sensitised RCD" nuisance trip as a result of
transients caused by the large inrush current. It probably only happens
when you manage to time the power on to coincide with the peak of the
mains waveform.

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


Yes - thanks - that is just what I had come to think it was as I read up after
making my post - and found about nuisance tripping.

However - as Tim+ questioned - was it the RCD? - and of course it wasn't.

I assume that I can put a larger MCB in - the cabling is a single spur from the
distribution box to the double socket in the garage - not on a ring.

What MCB would you suggest please?