switch blowing main fuse

[ban-all-sheds]

That's right, the extractor and the light were on the same circuit and the extractor was causing the problem. When you switched on the light you also switched on the extractor.

FFS.

And you didn't think to mention this right at the start?

 

[1john]

Never mind, at least a sparky got a call out fee to buy some chips for the family, although next time OP, if you give all details then we here may be able to help you or save you a few quid. You got off lucky, esp with it being a conversion, if upstairs had damaged a cable of yours it could get quite messy trying to sort it out!

 

[Jimmymack]

Thanks boys, to the sarcastic ones among you, if you bothered to read what I wrote you would have found all the info. It didn't take me long to add info as requested or as it came to me, it's not my problem if you missed it. If I was an electrician I wouldn't need to post questions here would I? The sparks was good, I couldn't have solved the problem so I would have needed to call him out anyway. ban-all-sheds put me on your ignore list.

To everybody else, thanks.

 

[ban-all-sheds]

All the info is not here:

One wall mounted light switch is causing the lighting circuit fuse on the consumer unit to blow. All other switches work fine. I noticed the switch was faulty so have changed it but the fuse still blows. Problems in changing the switch are that the wiring is old so the cables are black and red and the old switch isn't marked at all. So, I may have reversed he wiring but can't work out if this could be causing the problem to continue or even if I have the right solution. I've checked the other wiring as far as possible and it seems fine. The switch seems to be the key to it. Any info and advice is welcome.

Nor here:

So everything had been working fine, and without you changing/adding/fiddling with anything whatsoever on that circuit the fuse started blowing whenever you turned the light on?

That's exactly right.

I noticed the switch was faulty

What was the fault, and how did you notice it?

I noticed the switch was faulty just after the fuse blew.

So, I may have reversed he wiring but can't work out if this could be causing the problem to continue

It can't - switches just make and break a connection between the two conductors, they work either way around.

Thought so.

I've checked the other wiring as far as possible and it seems fine.

How have you checked it?

Looked at it for loose connections and water.

Any info and advice is welcome.

Unless you have a multimeter and an understanding of how electrical circuits are wired you're going to struggle. Getting an electrician might be your best bet.

Thanks, you've confirmed my suspicions but I live in hope.

Nor here:

Like BAS states, the wiring of the switch should not be a factor, the fault lies elsewhere, just out of interest how did you wire it and is there and earth cable?
and has any work been carried out in the property of recent?

I just wired it the same as the other using C at the top and L1 at the bottom. There is an earth cable which I just left alone. There's been work carried out to the property above but the main problems from there are usually to do with water leaking which was my first thought when it happened.

And here:

There's been work carried out to the property above.

There you go - that's the cause. Someone's put a nail or screw through a cable in the floor, or disturbed some wiring. Can you find out what they did where to try and home in on possible locations?

Is the property purpose built flats, or a conversion?

It's a conversion. I suppose that could still be the cause, the place above was completely gutted and rebuilt but this was finished 5 month ago. Another thing has occurred to me which is that there is also an extractor built into the circuit which could have a fault or even got water in.

you say there's an extractor fan on the same circuit, not that it's controlled by the same switch.

Even when I said

The fuse only blows when the you turn that one light on, so the problem lies in the switch cable or the light fitting.

you didn't tell us that the switch also controlled the fan.

So don't go telling us that we can't read, or missed things, when it's blindingly obvious that you didn't provide all the information.

The sparks was good, I couldn't have solved the problem so I would have needed to call him out anyway.

Really?

You think nobody would have suggested disconnecting the fan?

Don't judge everyone by your own standards - we aren't all as hard-of-thinking as you.

ban-all-sheds put me on your ignore list.

Better still, why don't you put this forum on your ignore list, and not come back wasting people's time again.