What is the best way to water proof my roof mounted lighting harness?

[GreenKoala]

I am looking to mount some lights to the roof rack, but I'm concerned about water entering the cab through the hole for wiring harness. I have not drilled, yet, so my plans are fluid. (hehe) Any advice on how to not mess this up would be appreciated. I'm very new to this.

 

[05XPeyelutt]

May I suggest Marine Sealant. You can find this in just about any Walmart in the boating/fishing section: Star brite Marine Silicone Sealant, Clear, 2.8 Fl. Oz. - Walmart.com

I sealed every accessible crevice on our old class C RV with it...works wonders, no more leaks.

 

[leeloo]

You use some rubber gromets that you grease a bit as well.
You find all kind of assortments on amazon.
If you need to install some kind of plug outside the the vehicle, or someplace exposed to rain, dust etc., best is to use a deutch plug, much better than anderson plugs when the connection is exposed to the elements..

 

[NCFireGuy]

I am looking to mount some lights to the roof rack, but I'm concerned about water entering the cab through the hole for wiring harness. I have not drilled, yet, so my plans are fluid. (hehe) Any advice on how to not mess this up would be appreciated. I'm very new to this.

Because I have a RAM I replaced the Satellite through roof system with Link Solar Weatherproof ABS Solar Double Cable Entry Gland for All Cable Types 2mm² to 6mm² for Solar Project on Rv, Campervan, Boat

 

[DMS1]

I would use dicor (removable\replaceable) or 3M 5200 (permanent)

 

[MidOH]

GE clear silicone caulk.

Not as fancy as RV or marine caulk, but works and is available everywhere.

 

[smritte]

Gland nuts. I use these for anything I need to feed through. Size them correctly and they don't leak. If you look hard enough they make them with a 90 degree end.
The link is just to show what they are.

 

[reaver]

GE clear silicone caulk.

Not as fancy as RV or marine caulk, but works and is available everywhere.

I've been informed that silicone on bare metal will cause it to rust (water or not), and fairly quickly.

I will second using a waterproof plug on the outside of the vehicle though.

 

[MidOH]

Well, paint it first.


Consider a plug, that's sealed with Ptex or silicone.

 

[madcratebuilder]

I am looking to mount some lights to the roof rack, but I'm concerned about water entering the cab through the hole for wiring harness. I have not drilled, yet, so my plans are fluid. (hehe) Any advice on how to not mess this up would be appreciated. I'm very new to this.

Can you run the harness out thru the engine bay up the side of the windshield? Most have room between the glass and body, use 3M tape to secure.

 

[MOAK]

Here’s the thing; the OP admits to being new at this and seeks advice. Well, I’m old at this and have ran a multitude of vehicles over the past 45 plus years. There in one thing I have never done. I’ve never drilled a hole in the roof of any vehicle. Lights up on the racks look cool. I had em up top on a couple of vehicles, however, as I recall, I didn’t care for them and soon moved them down on the front bumper. If you do insist on mounting them up top, I suggest finding a way to go down through the floor boards, then up the outside of the vehicle. Better yet, if you end up still having to drill through your roof, pay the money and hire a pro to do it. If it leaks it’s guaranteed. Then again, if you live in the southwest a leaking roof can’t be all bad as it very rarely rains there.

 

[MMc]

I am looking to mount some lights to the roof rack, but I'm concerned about water entering the cab through the hole for wiring harness. I have not drilled, yet, so my plans are fluid. (hehe) Any advice on how to not mess this up would be appreciated. I'm very new to this.

Good to hear from you, we at the meet up! ( I have the big grey stash) I would mount the lights up front. The overhead lights tend to shine on the windshield and hood. With them up front you are driving behind them without the glare. Maybe ask the guys at Expo pick up Subi after parts vendors for you!
Is there a bull ball or bumper replacement for the Subi. The overheads look cool but not the best for driving.

 

[smritte]

I removed my factory roof rack and used a couple of mounting holes from the factory nut serts. I have a power feed and two coax. I sized the gland nuts to match the existing holes that way "if" I ever wanted to remove them I just reinstall a nut sert.
Looking back I should have just cut a hole, used a 90 degree fitting and called it good.

In my profession, I have had to drill a whole bunch of holes in vehicles mostly for roof racks. I have a set of special hole saws just for that. If you use a drill bit with a stop (so it doesn't go deep), the bit will drill an oblong hole. Now you have sealing issues.
This isnt the brand I have but they look like this Hole Saw
You can also drill then open it one size with a Step Bit.
You need to make sure you have enough room to de burr the inside with any type of drill bit.

 

[MOAK]

I removed my factory roof rack and used a couple of mounting holes from the factory nut serts. I have a power feed and two coax. I sized the gland nuts to match the existing holes that way "if" I ever wanted to remove them I just reinstall a nut sert.
Looking back I should have just cut a hole, used a 90 degree fitting and called it good.

In my profession, I have had to drill a whole bunch of holes in vehicles mostly for roof racks. I have a set of special hole saws just for that. If you use a drill bit with a stop (so it doesn't go deep), the bit will drill an oblong hole. Now you have sealing issues.
This isnt the brand I have but they look like this Hole Saw
You can also drill then open it one size with a Step Bit.
You need to make sure you have enough room to de burr the inside with any type of drill bit.

Words from a pro

 

[velo47]

Gland nuts. I use these for anything I need to feed through. Size them correctly and they don't leak. If you look hard enough they make them with a 90 degree end.
The link is just to show what they are.

These are the way to go if you need to put a hole in the roof. And definitely take his advice on drilling, too.

 

[Road]

.
If you must go through the roof of your vehicle, RV, hardshell RTT, etc, gland nuts are great, as mentioned above.

Even better in most applications are entry cable glands; gland nuts enclosed in an entry that allows the gland nut(s) to be at a right angle to the mounting surface and further protects the hole itself from ingress of any weather. I'm using these on my van and hardshell. I point the entry to the rear of the vehicle or trailer. Excellent solution, professional looking, and long-lived.


(not my roof, though shows a good installation)

Most of us can use either a single or double, and they often come in white, gray, or black. Best suited to round wiring and cables.

Here's a whole page from which to choose: Entry Cable Glands

Be patient, know where your wiring will be routed inside, and figure it all out before drilling.

Good luck with your project.
.

 

[smritte]

I have that exact one on my trailer.

 

[Old Tanker]

You could run one of these along the A-pillar or the rear corner: Universal Wire Hider

 

[Sparksalot]

Gland nuts. I use these for anything I need to feed through. Size them correctly and they don't leak. If you look hard enough they make them with a 90 degree end.
The link is just to show what they are.

Agreed on the gland nuts. That’s what I will do if I have to run anything through the roof.

 

[old_man]

Gland nuts. I use these for anything I need to feed through. Size them correctly and they don't leak. If you look hard enough they make them with a 90 degree end.
The link is just to show what they are.

Ive been using these for decades on all sorts of stuff, even stuff that is under water 100% of the time....side scan sonar.