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There is a PVC conduit running under deck with a line for a hottub. It lies right on the ground. There is a junction box, which also lies on the ground with its cover up. It rains a lot here. (See pictures below.)

The junction box is Cantex R5133690. It got filled with water and that kept tripping the breaker.

I am trying to replace the junction box and redo the wire connections inside it. I also want to improve the setup so that it is less likely to happen again. I have never done this before, so have some basic questions:

  1. I want to replace the junction box with a square one, use elbows and raise it above the ground sideways. Is that a sound approach?

  2. If answer to above is yes, I will need 4 elbows, right?

  3. Should I use silicone instead of junction box's own rubber seal?

  4. Once I add elbows (which is additional ~20 inches for wires to travel), the wires are likely to be too short to be able to connect. What is the right way to fix this? Replace one of the wires completely with a longer one? Or add another junction box and a short wire between two junction boxes?

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    If needing to splice in wet conditions/areas(anywhere outside), there are water proof connectors for wires(rated for wet/outside conditions). If you used regular connectors it might why the breaker tripped.
    – crip659
    May 24 at 19:41
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    Are the unused ports wide open? There's a lot of debris in there, not just water. Anyway, it's an exterior conduit, so it's defined as a wet location, water is not going to be kept out by any means you'd care to pay for - put some drain holes in it as @EdBeal says. The box cover appears to be warped - you may need an extender ring to have enough space in the box if it warped because the junction does not fit, and you apparently need a new cover and seal.
    – Ecnerwal
    May 24 at 20:31

5 Answers 5

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Wrong box. Bad installation.

Why is the lid so warped? Far too much stuff was crammed into that box than was legal (cubic inch rules) or practical. So the installer just cranked down the lid screws as best they could, leaving huge gaps. 110.12 violation. Total amateur hour. Amateur hack-installed hot tubs are scary, so I would review the entire thing soup to nuts and look for other violations and shoddy work.

Apart from that, if you're doing a splice you want to keep water out of, why not attach the conduit and to the ceiling of this space (i.e. bottom of deck) so the box is face down? Then any water that gets in the box just falls out through the imperfect seal on the lid.

But use an adequately sized box, for Pete's sake. This box is intended for two 12/2 cables feeding a single light, a hot tub box needs as a bare minimum 25-35 cubic inches depending on if there's a neutral or not. I can peek through the product photo and see where it says "VOL 13" or possibly "15". So half the volume required for the job.

It's not enough to have a square box, you also need one both with the statutory 25-35 cubic inches, and also the practical space needed to hold the splice.

I know the cost of #6 copper is terrifying, but we have answers for that.

Elbows???

I'm not sure what are these "elbows" of which you speak. When dealing with conduit, you must assemble the conduit complete before you pull any wires into it. As such, the conduit must be "pullable". We get people who think "I want to make a 90 so I'll just use a plumbing elbow". You can't pull a wire around that, obviously. You need to either use special corners with access covers (for pulling) called "conduit bodies", or well placed junction boxes acting as a conduit body, or broad curves known as "sweeps".

Also you can't have more than 360 degrees of bend between access points. (which conduit bodies and junction boxes are, fortunately).

What I would do

If I were you, I'd pull the wires out of the pipe from the hot-tub end, then come down that vertical with either a 90 sweep or two 45s (depedning on the geometry) and then run the conduit along the bottom of the deck joists. Feel free to curve the conduit to the extent it is able, no need to "Minecraft" this thing.

By the way, "45" bends are a thing, as are arbitrary bends made by heating the PVC conduit - be careful not to kink it.

Then place a properly sized junction box, like I say, attached to the joists face down. Make splice(s) there. Nothing wrong with having two different splices a few feet apart, but replacing a length of wire run is also fine.

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  • If I attach the junction box to joists face down, should I drill holes in the lid? May 26 at 16:40
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    @Loki shouldn't be necessary. Just don't work too hard to tighten the lid perfectly. Like Ed says, the gaskets tend to leak, in this case that works in your favor. Remember use a large enough box. May 26 at 17:41
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Don’t change the box drill some holes in the bottom yes this is code legal and even required by code. All conduit systems that are not absolutely sealed condense water so code calls out holes even in conduit bodies arranged to drain. NEC 225.22,,, 230.53,,,and 324.15 not smaller than 1/8” or larger than 1/4” and code doesn't say how many holes so drill 2 or 3 and you won’t have a problem. I would turn the power off and hose out the gunk that is there but it will be fine and code compliant without spending anything for a new box no new wire or extensions needed.

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    Drilling the holes may be legal, but it seems the rest of the box isn't.
    – Mark
    May 25 at 22:08
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Expanding on a comment, Ed's still got the right answer which I've upvoted. But there is a further problem here.

That's a 15.8 cubic inch box.

You appear to have a junction of "wires of considerable, but unspecified size" - "Hot tub" is often a hefty feeder.

The top is blatantly distorted, apparently because the junction does not actually fit in the box. It obviously wasn't sealed, and can't possibly seal.

You need (at least one) round weatherproof box extension ring (and a new cover) to provide sufficient volume to splice wires in this box without violating box fill. How much you need depends on how many wires (4?) and what sizes (and if any are NOT spliced.)

Weatherproof box extender image from Platt Electric, no endorsement implied.

That box on it's own will just barely support 4 12Ga wires as a junction (only because of the ground wire discount.) 4 10 Ga wires (spliced) is 7x2.5 = 17.5 cubic inches required, and any larger wire size it just gets worse. If it's the normal 8 or 6 Ga for the power needed for an electric hot tub heater - no wonder the cover won't fit.

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At this point, you should think about redoing the run. Where the line enters under the deck, run the conduit along the bottom of the joists. Attach your new larger junction box, because the existing one is too small, to the bottom of a joist with the cover facing down. Position it to use the most unspliced wire. Then continue the run to the hot tub. If you need to install another junction box to use the rest of the wire, do so. It will cut down on the amount of wire you'll need to purchase.

I usually use the rubber seal that comes with the box but I run a small bead of silicone on both sides of it.

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    I use additional silicone if reusing a seal as the foam seals squash then don’t seal well a second time.
    – Ed Beal
    May 24 at 19:34
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How about pull a whole new cable without a junction box at all? A splice is unnecessary there if you run a continuous cable... and that gets rid of any possible water ingress issues causing the breakers to go.

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  • New cable would have to be UF to be outdoor rated. At today's copper prices, the #10 or #8 cable (probably) would be painfully expensive. Much cheaper to pull individual wires in conduit, even if buying all new conduit. Also, it would be protected by stapling it to the bottom of the joists, but it might have to go someplace that requires it to have physical protection which is going to require a big pipe for cable vs individual wires.
    – FreeMan
    May 25 at 16:12
  • @FreeMan I think that houninym actually meant a new cable within a continuous conduit - at least that is what I would suggest! May 26 at 11:17
  • "Cable" is 2 or more unmarked, individually insulated wires within a protective housing. Putting a cable in conduit means big conduit and a tough pull. "Wire" is a piece of metal (Cu or AL - solid or stranded) inside a layer of insulation, marked with its type information and designed for individual use. "Cable" could be run without conduit, but is expensive. "Wire" will have to go inside conduit which, when outdoors, is presumed to be filled with water once its been installed. Since he said it gets rid of water ingress, I presumed "cable". Maybe houninym could clarify what he meant.
    – FreeMan
    May 26 at 11:20
  • freeman... what i meant was pulling one or more insulated conductors through the conduit, either as separate wires or sheathed together... over this side of the pond cable and wire are kind of interchangeable as terms, I've seen a single stranded wire in insulation called a cable and three such things in an outer sheath called a wire... so there is no need for a join in the middle at all. And it could be in continuous conduit or in the existing conduit with the lid screwed down on the box... the box wouldn't be protecting a wire joint at all)
    – houninym
    May 26 at 14:18

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