Running Power Cable through outside walls

pbennison

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Nov 21, 2020
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I am nearing completion of my solar project and have a question.

I have (2) 2AWG wires (batteries),(3) 10AWG wires (PV Array) and 12 AWG AC power (generator) going through out side wall to inverter (located inside cabin) What is the best method to get cables through wall?

I was thinking of using feed through bushing for coax cable that would be good for the 10AWG and 12 AWG, however, I can not find anything for the 2AWG cables. Is a junction box my only option?
 

A.Justice

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I've seen PVC pipe, shaped in an upsidedown "U" shape used with good results. It keeps the rain out because it faces down, and if you stick a glob of butyl tape in the end, it will keep insects and air out.
 

Short_Shot

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Pvc exterior/waterproof junction box with a waterproof "gland" cable connector is one option.

The connectors come in all sorts of diameters.

My suggestion to you is to buy a waterproof (pvc or similar) junction box, a step drill bit up to 1 inch, and get one of these for each conductor you need to enter with. Face each gland down with a drip loop in the wire and caulk around the box.

Multiple conductors in one gland tends to leave small gaps where water can get in.

 

Alphacarina

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I've seen PVC pipe, shaped in an upsidedown "U" shape used with good results. It keeps the rain out because it faces down, and if you stick a glob of butyl tape in the end, it will keep insects and air out.
That's how I would do it. Use a pair of the 90 degree 'boxes' to make your 'U' shaped loop. The boxes have removable covers which makes it easy to run the cables and then when you're all done, shoot the boxes full of expanding foam and you'll be waterproof, bug proof and air tight

Don
 

Short_Shot

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That's how I would do it. Use a pair of the 90 degree 'boxes' to make your 'U' shaped loop. The boxes have removable covers which makes it easy to run the cables and then when you're all done, shoot the boxes full of expanding foam and you'll be waterproof, bug proof and air tight

Don
Insulating a current carrying wire is usually a pretty bad idea. Ideally you should oversize it so it doesn't heat up but insulation may require you to de-rate the conductor, especially if it's a longer run, and even if it's only a few inches worth.
 

DerpsyDoodler

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That's how I would do it. Use a pair of the 90 degree 'boxes' to make your 'U' shaped loop. The boxes have removable covers which makes it easy to run the cables and then when you're all done, shoot the boxes full of expanding foam and you'll be waterproof, bug proof and air tight

Don
for the 90 degree "boxes" i believe respondent meant conduit body outlets:

 

Short_Shot

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Isn’t there an NEC sub for pass-through / bulkhead wiring that basically says that? And support the cable within a foot of the box or something like that.
Idk.

But I do know we use them all the time for our panels near hydraulics specifically because they're liquid tight.

And if you need strain relief the gland does that inherently, though there are add-on strain reliefs available and of course you can secure it nearby.

Here's one on top of a panel. If it were outside it should be underneath the panel to eliminate standing water seeping into the connection however. That would also allow you to put in a drip loop.

20210908_010946.jpg
 

740GLE

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Do you have a drawing for your system? Im not sure why you are running battery cables from inside to outside. Are your batteries outside, and your inverter inside?

As for the generator connection, are you running a pig tail lead for a portable unit with a connector? or is this a full stand by generator on a pad directly wired?
 

Short_Shot

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Do you have a drawing for your system? Im not sure why you are running battery cables from in side to outside. Are your batteries outside, and your inverter inside?
Many folks put batteries in an exterior enclosure for safety reasons.

In some places it's mandatory by code I believe with newer NEC revisions.
 

740GLE

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Wouldn’t it make sense to keep the SCC/inverter in the same location? Reduces the run of larger conductors.
 

Short_Shot

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Wouldn’t it make sense to keep the SCC/inverter in the same location? Reduces the run of larger conductors.
Perhaps.

But the inverter will be much more sensitive to humidity and whatnot than your battery will be.
 

pbennison

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Originally I was going to put everything inside or outside. However, I decided that I wanted the inverter inside and the batteries outside. I simply could not decide which one was more beneficial. I built an enclosure on the ground outside to house and protect the batteries. I am not positive if the inverter is rated for outdoor use, but, looking at it from a purely laymen perspective I did not think it was. I also was not comfortable putting 4 (future 8) batteries inside the cabin. The space alone required for 8 FLA batteries inside a small cabin was a deterrent in itself .

In the end, I ended up using outdoor waterproof junction boxes with waterproof glands entering the box from below for cables going outside to inside. In total there is a midnite solar combiner box, a battery disconnect and all junctions boxes are under the eve of the roof which helps protect and eliminate some of the rain. Any wires entering junction boxes do so from below with drip loops and waterproof glands. Additionally, I put silicone on anything I thought may have the potential of water entering the box.

I will get pictures next time I am up at cabin.
 

rcrracer

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One size of a watertight cable connector. Could cram multiple wires through it and seal with whatever.
If entering through the top of a NEMA 3 box, could add a Myers hub.
Or a regular hub.
Or a bunch cheaper, enter box through bottom and use non watertight cable connector(s).
 
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