Permanently On Light

6 Apr 2006
Reaction score
United Kingdom
Hi everyone,
First post on the forum and am really hoping someone will be able to help me.

I've been living in my house for 3 years and have had no electrical problems. Then, all of a sudden yesterday, the upstairs toilet light wouldn't switch off, all the other upstairs lights are fine. I thought it was a faulty switch so changed it and it still stays on permanently. Then took down the light fitting and put in just a bulb hanging from a wire and it still stays on permanently!

Any ideas why after 3 years a fault like may develop and what the solution is?


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but HOW is it wired? theres at least 4 ways of wiring a lighting circuit and those are just the ones i can think of off the top of my head.
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Live and neutral come in to the ceiling and are looped into bathroom for the next light at the end of the circuit (the problem is in the toilet). From the live, a lead goes to the toilet lightswitch and returns to the ceiling to feed live to the light with the second connection from the neutral. As far as I'm aware, this is conventional. What do you think?

But either way, it has been working fine for 3 years so would could have changed in the past 2 days to make it malfunction?!
Have you been doing anything at all, maintenance wise, near to the toilet? New pictures or fittings fitted anywhere? Is it a wall switch or a pull switch?
right so that places the fault firmly with the switch cable (you've already replaced both switch and fitting)

i'd be betting on vermin damage but its hard to be sure.

how much of the cable can you easilly get access to and is there any obvious damage to it.
Pretty much none of the cable can be accessed because of wall tiling.
We do have a few woodlouse wandering around upstairs so I guess they could have caused some damage?
Woodlice... unlikely

Disconnect the switch drop both ends, do a continuity test across it, if there is continuity then you'll have to replace the cable :( (might be easier to install a ceiling switch instead of chasing and retiling?)
Thanks Adam and all, will give that a try at the weekend and let you all know if I get anywhere!
If I were you I would also connect another cable in place on the switch cable and put a switch on the end. If you operate the switch and the light responds you will have proven conclusively where the problem is.
Mystery Solved: For anyone wondering, there was a pipe (conduit?) sticking up through the loft floor that contained the switch wire to the toilet below. This was being rested on by a floorboard in the loft which over the course of several years wore though the protective wire coats and bared the wires causing a short. We cut the length of the pipe, and rewired the switch and it all works again.
Thanks for all your advice last week...
1) Did you do anything to protect the wires from damage in the future?

2) You're lucky it was a switch drop - that sort of thing can cause fires.

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