Small amount of water in bathroom pull cord switch

joe90mitch

Hi all,

We had been away for a few days and when we got back we found our bathroom light was dimly flickering, even though it was turned off (it was definitely switched off - when you pulled the cord again it came on full brightness with no flickering).

I turned the MCB off and took apart both the light fixture and the pull cord switch. There seemed to be nothing wrong with the light fixture.

The pull cord switch in the ceiling had a bit of water in it though, not exactly full but enough that when I pulled it down and tipped it slightly some water dripped onto me. I completely removed the switch from the ceiling and used a piece of toilet roll to try to push it into the hole in the ceiling and rubbed it around the flex, but it came out completely dry. This, along with the fact there's no other signs of a leak above, led to me thinking it probably isn't a leak above (by the way this is the first floor and there is a floor above, including central heating pipes and a bathroom if that factors in).

My current thinking is that maybe the switch is very old and maybe damaged, or wasn't screwed in flush, and condensation has built up over time to the point where it's just hit a point where enough has built up to touch the switch in the circuit/the wires themselves. We moved in 9 months ago and have no idea how old the switch was etc. I've still got the MCB off, with the switch and flex hanging down from the ceiling and can't see any water dripping down the flex (been about an hour).

My plan was to just buy a new switch, install it and then monitor over the upcoming weeks (including probably unscrewing it and checking for water buildup) - does that sound reasonable? My only thought is it seems strange that it would happen whilst we're away if it is a condensation buildup... If there's any other ideas or concerns I'm all ears.

Bendy_House

Blimey.

Well, I guess it must be either a leak or condensation. There are no other possibilities, are there?

You seem to have discounted a leak (it's dry around and above the hole), tho' this still needs confirming since it's possible that a small leak from the bathroom has dripped directly through that cable hole! Or, that water has dripped on to the actual cable, and then made its way down in to the switch.

That's one possibility.

Could it be condensation? Again, it's possible, tho' very unlikely. What could make it possible is that the ceiling void will likely be ventilated to the house's walls, so there could be a steady and constant current of bathroom air being dragged up that cable hole, so that would be getting in to the switch either via the small cord hole, or around the switch's joints. Once in there, it could be condensing... (I once traced a poor interweb connection by removing the phone wall socket and finding it corroded inside. This was on a modern house. The cause was immediately obvious, as you could feel the air being drawn into the wall cavity from the room through that backbox.)

Which is more likely? I have to say, I think it's the leak.

Worth buying a camera endoscope on t'Bay and connect it to your phone? Stick it up there and have a gander.

joe90mitch

Hmm yeah I understand your points, I am feeling quite anxious as I was thinking condensation but then I've got this nagging feeling in the back of my mind that it seems unlikely.

I'm a bit flummoxed all round, maybe the endoscope is a good idea. We also know that we want to redo the carpets upstairs at some point next year so I'm even of a mind to lift them (it would only be a metre from the wall) and lift one of the floorboards to take a peek.

Just confused what would even be leaking. It probably isn't central heating as our pipes run black gungey liquid (another hangover from the previous people we're trying to sort soon argh), and I've run the shower upstairs and flushed the loo and can't see any drips. Could a leak in the roof appear in the floorboards somehow - would we not see it appearing in the plasterboard of the top roof etc or could it work its way down? Just seems odd then that the flex and surrounding plaster would be dry.

Thanks for the useful answer anyway, after reading it and typing this out I feel like the best solution is just to try to confirm if there's a leak, either by a camera or just by pulling the carpet above to the side and lifting the floorboard - I know the wiring was done around 20 years ago so I wouldn't be surprised if I can simple unscrew the required floorboard and take a look.

Bendy_House

Unlikely to be from the roof - that would be a torturous route!

If you can lift the carpet and a board, then that's the thing to do. Have a cuppa, get some tools, do it!

If it is a leak - and chances are it will be - then it'll be a small one, enough to be a nuisance, but not cause catastrophic damage. At the moment.

The more I think about it, the less likely it is to be condensation. Even if a 'mist' formed on the switch surfaces during say shower use, the continued air flow would soon dry it all away. For a few drops to form is just sooooo unlikely.

Also good chance that the cables are the route in for the drops - it's the obvious way for water to get directly in there.

joe90mitch

Thanks a lot, will try to shift some furniture around this evening and hopefully take a look from above. If there isn't a board that's been previously cut out and lifted, then rescrewed in I might have to wait to either get an endoscopic camera or see if I can borrow a multitool (correct type of saw?) to lift a board.

If I can't lift the boards soon (or can lift them but see no obvious leak) I think I'll buy a new pull cord switch (might do anyway is this one is covered in paint from bodge jobs) and periodically unscrew it and see if there's any water ingress - obviously with the electrics off.

I get what you're saying with condensation. I'm definitely leaning against it now (just the fact that googling it returned next to nothing is usually enough of an indicator). My only last though is that our bathroom is really small and it's got no extractor fan. We do leave the (small) window open after every shower, but it takes an awful long time for all the steam to disappear... An extractor fan is on the to do list, though the boiler in the bathroom currently blocks the only available "easy" exit route - but that's another job for another day

Bendy_House

If it turns out there's no leak, so condensation is the most likely cause, then perhaps plugging the cable hole with something (loft insulation?) to cut down the air flow might be a solution. As well as spraying the switch with WD40 before screwing it back up...

But, man, add an extractor to your list

joe90mitch

Bendy_House said:

If it turns out there's no leak, so condensation is the most likely cause, then perhaps plugging the cable hole with something (loft insulation?) to cut down the air flow might be a solution. As well as spraying the switch with WD40 before screwing it back up...

But, man, add an extractor to your list

Yeah extractor is defo on the list. It's just a super narrow bathroom (1.2m wide) and the exterior wall is a Victorian solid stone wall, the boiler takes up over half of the exterior wall and the other half is the window... So there's not much room to manouever haha... Maybe I'll have to start a new thread on that for suggestions one day!

Just found time to lift two floorboards roughly above the switch. It was a bit of a nightmare to know if I was definitely above, as there were the laths of the old ceiling almost entirely in place, then about a foot beneath it the actual ceiling... Covered in loads of the old lath plaster argh!!

However I could see a flex disappearing into the ceiling and I know the wall next to it is the bathroom wall and there's no other fixtures there in the bathroom, so I can only assume it's the circuit going into the switch then another flex coming out to the light. But I can't be sure. But either way I couldn't see an obvious leak, though admittedly there's a lot of crap I couldn't move. You can just about make them out at the bottom left, going down into the ceiling beneath that piece of fallen plaster. With hindsight I should have got my partner to tug it from the other side.




I don't really know where to go from here hmm, I think back to shoving an endoscopic camera up and seeing if it's easier to see from that... 

But yeah I think I'll try to follow your advice to block air flow, put up a new switch and monitor regularly also.

NSG666

Getting your partner to tug it from the other side and shoving an endoscopic camera up????

Bendy, I think I'll leave this thread to you! 

joe90mitch

NSG666 said:

Getting your partner to tug it from the other side and shoving an endoscopic camera up????

Bendy, I think I'll leave this thread to you! 

Hahaha I did actually type out "oooeerrr" after the tug comment and then sadly decided to delete it...

Bendy_House

Gentlemen!

That's typically messy, Joe. But completely dry? Wow.

If you mark that cable with a pen, and then 'tug', you should be able to tell if it moves - ie if that's the right cable.

joe90mitch

Bendy_House said:

Gentlemen!

That's typically messy, Joe. But completely dry? Wow.

If you mark that cable with a pen, and then 'tug', you should be able to tell if it moves - ie if that's the right cable.

Good idea.

I can't definitely tell if it's dry in fairness, just nothing obvious... but then if the leak had happened, say, 50cm away and run underneath all the plaster mess I'd have no idea. There's no pipes directly above it, though the shower tray upstairs is somewhat in a similar area. It just seems odd to me that the flex and plaster around it seems dry when inspecting from beneath if a leak elsewhere has run down towards the switch. I've also had the flex just hanging out of the ceiling all day and so far there's been no other water... It's so strange (like I said earlier, have made sure to run taps, flush the loo, run the shower upstairs and the central heating is on). I hope it's not vermin wee hahaha......!

Problem is there's only a tiny gap in the lath for me to reach through where one lath has broken. Am I ok to saw/break more off? I'd assume so? Then I guess I could also move the rubble to one side and touch the ceiling to see if there's any water.

I've had to tidy it away for now as we've got guests staying in that top room tomorrow night - selfish! Will have another go soon though. I've also ordered a £5 endoscopic camera as per your suggestion in case that shows enough from pushing it through the fixture hole.