* Rob Malpass (rob@???) wrote:
> Hi all
>
> [Very ot I'm afraid]
>
> My father-in-law has just come up with another gem - and as it's been quite some time since I've done any electronics, I thought I'd ask for confirmation of my suspicions.
>
> Apparently he switched on his PC and it promptly blew a circuit breaker back at his house's distribution box! Now as I recall, P=IV. I=13 Amps, V=240 so unless his power supply is something like 3000 Watts (enough for a kettle or electric fire), there isn't much chance of the culprit being his PC. There isn't much else in the room (or on the circuit) he uses - nothing like a kettle or electric fire anyway!
>
> So I've suggested he:
> a) plugs a kettle into the same wall socket - to see if it trips the circuit breaker.
> b) moves the computer downstairs - to see if he can get it to work.
>
> Any other obvious things I can try? Has anyone else had a situation where a PC has blown a domestic fuse?
First, was it an over current breaker or and RCD? An RCD may be
rated to carry 13A or whatever, but will trip when there is an
imbalance of maybe 30mA between live and neutral.
I used to work for a domestic appliance manufacturer. They had a
recurring problem where toasters would trip switches. Lots of
research by our engineers and the manufacturers of the trip switches
failed to come up with a definitive cause, but it was believed to be
some surge that was difficult to measure when the switch in the
toaster activated.
It could therefore be a problem with the power supply surging when it
comes on. Or, it may be a slightly over sensitive switch. I am sure
there is a tolerance with these things. Does he have another of the
same rating on another circuit? You could try swapping them.
Finally, does he use a spike suppressor on the PC power supply? If
one is available, it may block any surge caused by the PC PSU from
reaching back to the breaker.
<disclaimer>
By the way, I am not an electrician, nor am I qualified in
electronics, so I should say, if you are not sure what you are
doing, call a qualified person.</disclaimer>
--
Philip Stubbs
http://www.stuphi.co.uk
