Junction box drainage hole

[scrambler]

A quick practical question here.

Has anyone found out that humidity builds up in the small Junction Box on the roof where the strings are connected to the wires going to the inverter.
I am wondering if I should worry that this would happen and damage the contacts in there overtime, and if a drainage hole should be drilled in the junction box.
Note: I am in Northern California, so no extreme weather here.

Thanks

[SunEagle]

If you decide to put in a drain hole just make sure it is at the lowest point so the moisture goes out it instead of down a conduit opening.

[scrambler]

Absolutely, but curious to know if I need to worry about condensation in the box.
From your answer, am I right to assume you don't consider it an issue?

[Duxa]

The wire that is used should be rated for wet location, like THWN (-2), and the transition point should be done with outdoor rated fittings/connectors. If thats all done properly the wires should do just fine when exposed to condensation/moisture. That being said, a lot of the Jboxes meant for outdoor locations come with weep holes (to drain moisture). So it is possibel to make your own (but see the note below). Also, if possible create a drip loop with the cables.

From 314.15 - https://www.electricallicenserenewal...sectionID=64.0

2014 NEC allows weep holes in the box as long as the hole is ¼ in. or smaller. There is no limit on the number of holes or location where they are drilled but the holes must be “approved”.

According to Article 100, “approved” means acceptable to the authority having jurisdiction. Basically, any drilled holes are subject to the approval of the inspector.

Here is 2017 revision:

https://imgur.com/a/I9CfDgp

[SunEagle]

Absolutely, but curious to know if I need to worry about condensation in the box.
From your answer, am I right to assume you don't consider it an issue?

When a conduit goes from one type of environment to another (ie. cold to warm) you can find moisture will travel through the conduit to a "box". But if the box is sealed and there isn't much difference between the conduit environments then there is little chance of moisture getting into the box.

[emartin00]

The wire that is used should be rated for wet location, like THWN (-2), and the transition point should be done with outdoor rated fittings/connectors. If thats all done properly the wires should do just fine when exposed to condensation/moisture. That being said, a lot of the Jboxes meant for outdoor locations come with weep holes (to drain moisture). So it is possibel to make your own (but see the note below). Also, if possible create a drip loop with the cables.

From 314.15 - https://www.electricallicenserenewal...sectionID=64.0

2014 NEC allows weep holes in the box as long as the hole is ¼ in. or smaller. There is no limit on the number of holes or location where they are drilled but the holes must be “approved”.

According to Article 100, “approved” means acceptable to the authority having jurisdiction. Basically, any drilled holes are subject to the approval of the inspector.

Here is 2017 revision:
https://imgur.com/a/I9CfDgp

It's not the wire you need to be concerned about, it's the connectors. The vast majority of connectors are not designed to be exposed to the elements, and will corrode quickly in a wet environment.

[Duxa]

It's not the wire you need to be concerned about, it's the connectors. The vast majority of connectors are not designed to be exposed to the elements, and will corrode quickly in a wet environment.

Have had silicone filled wire nuts on my sprinkler wires for 20 years or so... functioning like they did on day 1.
For solar roof jbox use one of these splice connectors (pic below), or if AHJ permits outdoor rated silicone filled wire nuts. Should be fine. But its never ideal to have it sit in water, so if water can get in, weep holes are a good idea.

97020_l.jpg

[SunEagle]

Have had silicone filled wire nuts on my sprinkler wires for 20 years or so... functioning like they did on day 1.
For solar roof jbox use one of these splice connectors (pic below), or if AHJ permits outdoor rated silicone filled wire nuts. Should be fine. But its never ideal to have it sit in water, so if water can get in, weep holes are a good idea.

97020_l.jpg

I don't know about wire nuts. Based on my experience if they see a big temperature change they come loose over time. A terminal strip inside a junction box is a better way to join wires.

[solarix]

I've seen "watertight" j-boxes half full of water. Yes, condensation is a problem. I use a 3/16" weep hole unless the inspector forces us not to. Hole just big enough to not plug up with debris and too small for spiders etc....

[scrambler]

May be I will drill a weep hole, plug it with a screw, then open it up every few month to see if water ever builds up inside...

[Mike90250]

I would never use wire nuts of any sort for solar connections. The nuts eventually fail over time under the demanding constant power loads.

Either split nuts or screw down wire splices