On Jun 27, 6:54 pm, Palindrome wrote:
paulfoel wrote:
Got a bathroom fan thats been there since the house was built (only 7
years ago). Its got a pull string switch as you go into the bathroom
and the fan is on the opposite outside wall.

Been working fine until one day when I turned it on it tripped the
circuit breaker. My circuit breaker is in the garage and has got a
main switch as well as switches for upstairs/downstairs lights,
upstairs/downstairs sockets etc - it tripped the upstairs lights one.

Tried again - tripped again.

So far, I've :-

1. Replaced the pull switch - still the same.
2. Replaced the entire extractor fan unit with a new one - still the
same.

I'm afraid thats the limit of my electrical knowledge now. Anyone got
any ideas ?

Many bathroom fans were supplied with an external timer unit, so that
they would remain running for a few minutes after the light was turned
off. Newer ones tend to have the timer unit built-in.

If your existing fan unit didn't have two reds (one switched, one
unswitched) and a black (plus a green/yellow) and it stayed on after the
light went off, then you have an external timer unit.

The timer unit typically uses a capacitor/resistor series circuit to
lower the input voltages to that used by the electronics. The resistor
can overheat and damage the board with time, which can allow tracking,
leakage current and circuit breaker trips.

It would be easiest to simply replace the timer unit, if that has
failed. However, the wires going to the timer unit can be taken to a fan
unit with built-in timer, instead.
--
Sue

Sue,

Thanks for the info.

I have, however, tried a completely new unit...