Wire through roof for solar - leakproof

[Dave Nathanson]

I'm looking for a good way to get a wire through the TD roof without leaking. I'm open for suggestions. The goals are to protect the wire from chafing on the hole, and not leak from rain nor enthusiastic washing.

Two wires actually, each is 1/4" diameter - they are 10 gauge from the solar panel. The TD roof is 3/8" plywood covered with 0.040 aluminum, and a retrofitted layer of thin insulation & 2nd layer of thin paneling . That retrofit adds maybe 1/2" and it is easily removable. The spot where the hole will be drilled is behind the roof vent & to the drivers side, near the front edge of the solar panel, which is a few inches above the TD roof. So the wires & sealer will usually not be in direct sun. The wires will come out in the cabin behind a cross beam, so it's likely no one will see them, nor the hole from the inside.

Here are some of the ideas I've had so far. (Not saying these are good ideas!)

1) Silicone. Drill a 1/2" hole, stuff the wires through & seal with plenty of silicone.

2) Flange & Short pipe. Drill, put a short pipe with elbow through, and seal. Could use a pipe floor flange to secure it to the top of the roof. Seal with silicone all around the flange & everything.

3) Thru-hull fitting. Some sort of marine fitting. such as a Seachoice Cable Thru Hull Fitting Requires 3/4" hole, but it looks pretty long.

4) Liquid-Tight. There are a number of liquid tight electrical fittings, but they all seem so huge, and I'd prefer to drill the smallest hole practical in the roof.

5) Drill two 1/4" inch holes to make a 5/8" oval, insert some 3/8" id flexible vinyl tubing, run the 2 wires through the tubing and seal everything with silicone. If the tubing is about 8" it can easily cover all the vertical wire. Secure top end of wires & tubing to solar panel rack. Advantage- top end is sheltered under solar panel rack. When ovaled the 3/8" ID tubing is almost a perfect fit for two 1/4" wires.

6) Bend some metal tubing into a candy cane shape, insert the straight end into the roof hole, figure out how to affix, and seal all with silicone. Disadvantage: stiff metal tubing has leverage - will probably wear the hole & pull loose under stress.

So far, I'm liking #5, flexible vinyl tubing around the wires & goop it up. Or maybe #3, the through-hull fitting.
What do you guys think?
Dave

[MtnDon]

Does it have to be in the roof? A hole in a sidewall is likely less prone to a leak... I like the liquid tight electrical fittings myself. Silicone is good but does have the disadvantage of new silicone will not seal to old silicone. If a removal and replacement is ever necessary that can be a pita.

[George Taylor]

If the wires you will use are 10 awg, you might be able to use standard 10-2 sjo cord and then get a 90 degree water tight connector for it. That way all you will have to do is drill a hole in the outer skin to fit the connector. The hole in the plywood will need to be slightly bigger to accept the locknut for the connector.

[Lgboro]

I used a thru the hull marine fitting. 3 years plus and 25,000 + miles without any issues. Mine wire runs under the solar panel and is fairly well covered anyway.

[Dave Nathanson]

Hey George, Lgboro & Don,
Can you point me to the fitting you used?
Thanks!
Dave

[MtnDon]

Lowes, HD, Menards, Ace Hardware.... will all have them in metal and PVC varieties. Straight and some 90 degree abgled ones. Ask in the electric dept or wander the rows near the conduit and fittings section.



Threads and a lock nut on the hidden end.

[lrrowe]

MtnDon, please excuse my denseness. I see how this connector is watertight to the CT, but if you put two wires through it and tighten it, won't there still be a gap for water to pass through?

[jss06]

This is how I routed mine. I bought a small clam-shell marine fitting. Drilled the hole and ran the wire. Caulked in the hole and mounted the fitting to cover the entry hole. Pushed more calk up into the fitting around the wire. It did not leak on my trip to/from Yellowstone and I ran into to some nasty storms on the trip.

[MtnDon]

There is a flexible 'grommet' that the cap nut compresses. The ones I have used were actually called gas tite and could be used in explosive atmospheres to isolate electrical switches in boxes. Maybe not quite the same as the ones in the conduit section of the big box stores.... ? I got mine by taking apart surplus military electrical boxes and devices.

[bc toys]

Bob the compress around the wire as you tighten them up so they will seal I've worked with them on many jobs and never had one leak we use the metal type

[George Taylor]

https://www.platt.com/CutSheets/idw/tho ... ochure.pdf if you go to page 5 they have a picture of what I am talking about.

[lrrowe]

Bob the compress around the wire as you tighten them up so they will seal I've worked with them on many jobs and never had one leak we use the metal type

After looking at some photos, I think I understand it if it means putting the cord of 2 or 3 wires through the connector and then compressing that. The cord is one round item. I thought others like MtnDon were saying to put two individual wires through and the clamp. That is the scenario that was hard for me to see how it could be liquid tight. Hope that makes sense?

[angib]

A deck connector from a boat would be ideal as it's leakproof (if done right), plus you can disconnect it if you ever need to remove the panel.

http://www.jamestowndistributors.com/us ... nd+Sockets

[Shadow Catcher]

I used the deck connectors and have not had a problem.

[lrrowe]

Will they work with the required gauge size wire needed for multiple solar units? That is something I am going to have to research.