Dave Plowman (News) wrote:
In article ,
Rob wrote:
One of the few (obviously!) things I remember from physics at school is
that you should use the appliance switch if it has one to avoid damage,
rather than the socket switch or pull the plug. Is there any truth to
this?

I take it your physics teacher had a degree in physical education? Because
it's basically rubbish. Although some devices like projectors have cooling
fans which are meant to run after powering down, but I'll bet he wasn't
thinking of those.


No, she (it was a 'she', Dave, and not a 'he' - Ms Lyons, class 3C, BVGS
Birmingham 1976) was/is a physics graduate although she didn't have a
PhD - or at least she didn't use the title 'Dr' (most of the other
staff did). I'm afraid I can't remember if she was a member of any
chartered or similar organisation - sorry.

I was trying to remember last night - I asked her 'why?', and I'm pretty
sure the answer had the word 'surge' in it, and tailed off into a 'this
doesn't apply to everything but as a rule you shouldn't switch a
switched device on or off at the mains. Device first, mains second'. I
tried it with my system - 3 valve amps, TT and CD, and left them
switched on at the appliance and just flip the switch at the mains.
Mighty convenience, but hell of a thump at the speakers when it's
switched on, fine when switched off.

Rob