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