Outside light query

[GB]

We have an outside light - an oblong plastic thingy - in a rather exposed position. I opened it up to change the bulb, and there was some water inside. What's the best way to stop this?

I thought of putting a couple of drain holes in the bottom, but that seems too bodgy even for me.

The two parts of the lamp push together with a flange, but there's no rubber seal between them. Is there any simple way of making a seal that will still allow me too open the lamp again to change the bulb?

It looks similar to this one:

But that one is waterproof!

[Bob Minchin]

Drain holes in the lowest point are the way to go.

An outside container is very difficult to fully seal as thermal expansion/contraction will act as a pump admitting small amounts of water vapour laden air. The water condenses and stays inside and on the next heating cycle the air gets pushed out but the water does not and so it slowly builds up as the cycle repeats. You still really need some sort of seal against driving rain. I often use a silicone grease - Dow Corning MS4* smeared over the sealing faces and wipe off any excess that squeezes out when you fit the cover.

• I think it has another name now (DC4?) but my toothpaste sized tube will see me out so I've not bought any of the new name stuff.

[Dave Liquorice]

Double plus 1. Not many people realise/know that.

So although holes seem bodgy it's the only way. Only need one at the lowest point and it doesn't need to be very big 1mm is ample. Much bigger and a decent blow will manage to force water in, not to mention letting in spiders or other wild life.

[Huge]

The spiders get in anyway. I have no idea how.

(Over the last few weeks I have dismantled all the outside electrics in the so-far fruitless search for the nuisance RCD trips, and they all had spiders in them. Even the IP44 junction boxes.)

[GB]

Thanks! So, tiny hole to allow air in and out, and use grease to seal it. Brilliant! Why didn't I think of grease?

Curiously, we have two of these, one under the eaves in a very sheltered position. That was bone dry inside, so I'm not 100% sure that condensation is really an issue. It's possibly simpler than that.

[GB]

Mind you, the dry one is south-facing, so gets lots of sunlight on it.

[John Rumm]

That's actually fairly normal practice - a 3mm hole at a low point...

Get a tube of silicone grease from CPC. That will help seal, but does not set or prevent you pulling it apart later.

or change the fitting for a waterproof one (although even waterproof ones may still leak a bit)

[Andrew Gabriel]

Spiders can generate RCD trips.

My parents have a desk fan (class 2 - double insulated) which has a 2-core cable and a plastic body. I was initially rather surprised that it caused an RCD trip. The culprit was found in the plug - a spider's web/nest between the live and earth.

[Huge]

I know. That's why I've been cleaning them out.

[Graham.]

So can ants. I once had a chain of them like a U-link between E & L in my boiler junction box.

[ARW]

Have you still not done the divide and conquer by fitting RCBOs?

[Harry Bloomfield]

on 10/02/2017, Bob Minchin supposed :

+1

I always add a series of tiny drain holes to any fitting which is outside in the weather. No matter what you do, water will get in, just make sure it can get out more easily.

[newshound]

I'd go with the holes (I have done this myself, in the past). An interesting philosophical question, when does a sound, pragmatic DIY fix become a bodge?

That's of course assuming the holes are sufficiently far from the wires that worst case driving rain, or even direct spray with a hose if you are in the habit of doing that sort of thing, won't get on the exposed connections.

[tabbypurr]

A repair that is effective, reliable, safe, works ok & looks ok is good. Anything that fails those is a bodge.

NT

[Huge]

Can't bring myself to spend that amount of money with no guarantee of improving matters. Haven't had one for a couple of weeks now, after taking the feed to the Klargester & workshop out of circuit.

[Brian Gaff]

Might also be a nice idea to have some silica Gell inside as well. However, some floodlights that look like they were built to withstand a nuclear attack on a nearby 'listed' building still get water inside, apparently, so I think the point is that there will always be some moisture in sealed units. Brian

[ARW]

Fair enough.

BTW RCDs are like women - they are both over sensitive and will not tell you why they turned off

[Huge]

LOL. Since it's "not too expensive", I've ordered a replacement RCD, which I shall fit myself. I don't hold out much hope, but you never know...

[John Rumm]

Bit like one of my PIRs:

[Huge]

Yep. They all looked like that.