Are Deta indoor/outdoor junction boxes really suitable for outdoor use?

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neb

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#312126 19-Mar-2024 18:52

Helping a friend run some conduit and after a ton of drawing cable, including several false starts because we'd got it on the wrong side of something immovable, we got to where we'd need the first junction box. However this supposedly-OK-for-outdoor-use box has no gasket or any other attempt at sealing, just a somewhat loose-fitting lid that you screw into place, and there's no trace of an IP rating anywhere on it or on the Deta site.

In its favour, the screws are SS so it's at least planned for outdoor use.

Has anyone used these outdoors? How do they hold up to rain or moisture in general? In this case if any gets in it's going to run downhill via the convenient pipe to where the electronics will be located.

mattwnz

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#3208143 19-Mar-2024 19:00

Can the conduit be bent up in an L shape, so if water does get into the box, it won't then drain into and down the conduit to the lowest point in the system? eg the conduit essentially creates a gravity dam preventing water getting beyond the bend. Does the box itself have a drain hole in the bottom to release water. However any hole could allow bugs to get in and block it over time, Have you had a look at PDL, as they usually have some IP rating and seal. But any box can leak over time.

neb

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#3208144 19-Mar-2024 19:04

We used the dubious waterproofness as an excuse to knock off for the day so the junction box isn't in place yet, which means we could substitute something else before proceeding rather than having to band-aid it.

It has a small slot that goes as far as the lip on the lid which seems like it's meant for some sort of ventilation, possibly to relieve pressure from long sealed runs, but I doubt the rest of the lid is even remotely airtight so I'm not sure if it's necessary. In any case it won't allow water to drain because it's up and to the side, not at the bottom.

neb

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#3208147 19-Mar-2024 19:08

Here's a photo of it open, I've seen indoors mains junction boxes that look more weathertight than this:

mkissin

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#3208230 19-Mar-2024 21:49

Even the normal Marley junction boxes are IP52, which is just a suggestion of water resistance. If you're worried, drill a little drain hole in the bottom so any water can exit, or buy one of the ones that does have a gasket. Marley has some, and I assume Deta probably does too.

skewt

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#3208233 19-Mar-2024 21:54

We have used ones like that outdoors and they have been fine, add some extra silicone to seal it up

neb

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#3208240 19-Mar-2024 22:12

mkissin:
buy one of the ones that does have a gasket. Marley has some, and I assume Deta probably does too.

You can get IP54 or similar ones from a range of manufacturers but they're just square boxes with knockouts so you need to faff around with gaskets for the conduits rather than having them moulded in like the existing junction box. There doesn't seem to be anything that's got the moulded-in conduit connectors while also having any kind of IP rating.

Solution at the moment will probably be using the Detas but wrapping white PVC electrical tape around the seam to waterproof it since the Internet seems to think that'll hold up for quite a long time, and possibly nailing a strip of 2x4 over the top to prevent most of the rain from hitting it.

SomeoneSomewhere

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#3208242 19-Mar-2024 22:20

Generally, conduit used outside is going to get wet inside regardless of how much you try to seal it. Condensation in particular is a major issue.

Best practice is to avoid joints in conduit boxes to the greatest extent practical.

Where you do need to make joints/terminations, the main considerations are:

Ensure water can't pool anywhere that has a joint - drill holes in the bottom of boxes; most outdoor sockets have a specified 'drill' point. You can also use fancy drain plugs that come with an IP rating; one manufacturer was making a song and dance about it a few years ago, but I can't find much now.
- Explosion proof products need certified breather plugs, but you don't want to price them...
Ensure that moisture running/tracking along cable can't get to terminations - 'drip loops'.
Ensure that your splices (in screw connectors/wagos/whatever) are arranged as 'hats' not 'buckets'.

If you want truly waterproof joints, you forget about the conduit and go to crimps/solder and heatshrink, probably backed up by potting compound.

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neb

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#3208269 19-Mar-2024 23:29

In this specific case it isn't being used as a junction box but merely to provide for future expansion, so we're taking a loop out to a 1-way junction box (line runs out, loops around it, comes back in again) to provide some slack to splice in something in the future without currently severing the cable at any point. It may never get used, but given the amount of effort it's taken to run this so far, having a location halfway down the run where something can be added seems like a good precaution.

neb

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#3208994 20-Mar-2024 23:40

This is what the final product looks like, before it's attached to the fence behind it:

There's a double loop of white PVC electrical tape around the seam which isn't too visible in the photo, lets see how that holds up. As explained in a previous post, the side lobe just contains a loop of the cables, if it's ever necessary to splice in something at that point we can cut the conduit open and use the cable slack looped in the junction box to add a new connection.

Wombat1

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#3208995 21-Mar-2024 00:51

I would not use one of those without a rubber seal for outdoor use. Perhaps outside under the eves but not in the direct elements.