On Jun 30, 7:02 am, Palindrome wrote:
paulfoel wrote:
On Jun 29, 5:46 pm, Palindr me wrote:

paulfoel wrote:

OK. So the upstairs light circuit has got on it:-

- 3 combo fan/lights (3 bedrooms)
- 2 normal lights (1 bedroom, 2 bathrooms)
- 2 fans (2 bathrooms)

The one switch for one of the fans is causing the trip when its turned
on...

However, is it possible that the fault could like elsewhere in the
circuit ????

There are many more explanations that are possible, but unlikely:

1) The total load is enough to trip the mcb. So try the switch with
everything else on the circuit switched off.

Still trips. Like I said this has all worked fine for years !!!!

The scenario I'm thinking of is that the original fan went faulty -
hence tripping the mcb. However, in putting in the new switch and new
fan, you have introduced a new fault. Say by mis-wiring the double pole
switch. It can be easy to do - the terminal layout on the new switch may
not be identical to the terminal layout on the old one..



2) The mcb is faulty and tripping on the fan motor start up - even with
everything else off. So try swapping the mcb with a different one.

Gulp! Sounds difficult...

It is potentially lethal - as has been the things that you have already
done, such as changing switches and mains fans. If you are at all unsure
about what you are doing with any household electrics and feeling
nervous - your instincts for self-preservation are kicking in with good
reason. Listen to them. Do an evening course at your local college..
then you will be happy taking on anything.



3) The fan switch is a two pole one and wired incorrectly. So it shorts
the supply when pulled. Check the wiring.

This was working OK.

Then you changed it. Are you absolutely positive that you wired the new
switch correctly?



4) The replacement fan is also faulty or wired incorrectly. So try it on
a 3A fused mains lead.

Hmm. Doubt it...

All of these possibilities are remote. But there has to be something
wrong, somewhere.



5) You have been doing DIY and put a nail through the fixed wiring from
switch to fan. So replace the cable.

Nope.

Shame! That was one of the more realistic possibilities..



6) Rats have eaten through the cable in the loft/ behind the wall.
Replace the cable.

LOL. Dont think so !

It has to be something. If the mcb is ok, the switch is ok, the fan is
ok, there is nothing else switched on - then it has to be the wiring.



7) etc

So, try the following in sequence:

1) Disconnect the output cable from the switch and try the switch. If
the mcb trips, the switch is faulty or wired incorrectly.

Yes. Someone else suggested that...

So, have you tried it?



2) Reconnect the output cable to the switch and disconnect the wires
from the fan, suitably insulating them in a choc box multi way
connector. Operate the switch. If it trips, you have a cable fault - eg
rats have bitten it.

Whats a choc box multiway connector ????

http://www.maplin.co.uk/images/Full/l96_99ar.jpg

They are normally used to join wires /cables together *inside* equipment
- where there *can't* be any pull on the wires and *can't* be any
possibility of touching them. But they can also be used on the end of
unused wires inside boxes, to insulate the wire end - or used to
temporarily insulate the ends of free wires which aren't connected but
may be going to be made live.



3) Reconnect the fan and operate the switch. If it trips, swap the mcb.

How difficult is that? I've got a posh looking panel in the garage
with switches on !!!!

It isn't difficult but it has to be done with absolutely no mistakes,
first time. The inside of the box will be live in places at all times.

Doing an evening course in domestic electrics makes sense. House
electrics really isn't the thing to learn by trial and error. It only
needs one teeny mistake to end up with someone dead or with the house on
fire.

It sounds like you ought to get an electrician in, this time..

--
Sue

Hmmm. OK. thanks for the advice...