Ground connection for roof mounted accessories (1 Viewer)

[mcgaskins]

I'm installing several scene lights on the sides of my roof rack as well as a reverse light and light bar up front. I have a switch/power panel that goes under the hood and has positive leads running from the box to go to each accessory, but I'll need to run grounds from accessory on my own. What is everyone doing for grounds on the roof rack? I was thinking of using a bus bar like this (Amazon.com: Sea Dog 426710-1 Line Buss Bar Terminal: Automotive) under the hood, and then I would run both the positive and negative wires from each accessory to roughly the same spot under the hood. Normally I would try to find a closer ground to the chassis for each accessory, but I'm not sure if there are places on the roof that are suitable. Most of the lights I'm running have a low amp draw of ~1-3 amps with the exception of the light bar which will be around 11. Here's an example of one of the scene lights:

 

[Mogwai]

What is the "switch/power panel" you speak of? I have two of these in play, one on the right side and one on the left side of the vehicle: Amazon.com : Blue Sea Systems 5025 ST Blade Fuse Block - 6 Circuits with Negative Bus and Cover : Auxiliary Fuse Block : Sports & Outdoors The only reason I'm sharing is that they both have a negative bus w/ each, so I don't have the same setup as you do.

And I don't yet have a rack/lights on the roof but planned for them, basically planning to run wires up both sides of the vehicle like @linuxgod did (at least I think it was him, 3/8 wire loom running up his driver side). You probably can't fit all the wires into one loom which is why I opted for a circuit on each side. If you already have the "switch/power panel" I don't see why you couldn't add one of those negative bus terminals that you posted, next to whatever battery you're running your lights from. I would run both positive and negative up to the roof as you suggested. Or what about mounting one of those negative bus terminal somewhere up on your rack where you can't see it? I don't *think* water would be an issue but maybe get one that's sealed and just know eventually it might corrode and you'll have to replace. But that way you could run a single ground wire to the roof vs one for each light circuit.

 

[mcgaskins]

What is the "switch/power panel" you speak of? I have two of these in play, one on the right side and one on the left side of the vehicle: Amazon.com : Blue Sea Systems 5025 ST Blade Fuse Block - 6 Circuits with Negative Bus and Cover : Auxiliary Fuse Block : Sports & Outdoors The only reason I'm sharing is that they both have a negative bus w/ each, so I don't have the same setup as you do.

And I don't yet have a rack/lights on the roof but planned for them, basically planning to run wires up both sides of the vehicle like @kreiten did (at least I think it was him, 3/8 wire loom running up his driver side). You probably can't fit all the wires into one loom which is why I opted for a circuit on each side. If you already have the "switch/power panel" I don't see why you couldn't add one of those negative bus terminals that you posted, next to whatever battery you're running your lights from. I would run both positive and negative up to the roof as you suggested. Or what about mounting one of those negative bus terminal somewhere up on your rack where you can't see it? I don't *think* water would be an issue but maybe get one that's sealed and just know eventually it might corrode and you'll have to replace. But that way you could run a single ground wire to the roof vs one for each light circuit.

I had planned to go with the Switch Pros module, but I couldn't find a good mounting solution inside the cab without hacking something up which I want to avoid at all costs. I bought this Trail Toys NSA switch panel which is remote control driven to avoid running any wires through the firewall. I admit it looks a little cheesy at first glance, but there are obviously some big benefits to not run wires into the cab. You can store the remote wherever you want, you have lots of programming options, and one of the coolest features is you can turn on every wired accessory with a single button push. I'm only running lights to the panel, and one use case I've considered is if we're out camping and we hear some strange noises creeping around camp...I can hit that button and turn the truck into a 10,000+ lumen spaceship looking thing to whatever 2 or 4 leg critter (we imagine) is trolling around

 

[TonyP]

A dedicated ground bus is a good idea. Grounding to the chassis can cause issues in the long term.

 

[Mogwai]

Wow that thing is pretty cool. Trying to figure out switches myself. I know @RET2 is working with S-pod to design a braket that would sit in the space in the far back passenger side (over the fuse relay box). That space is prime for a plate to mount stuff. Justdifferentials mounted their compressor there and I had contacted them about the bracket, evidently it was a one off and they wouldn't be able to replicate.

Let us know how that bad boy works out.

 

[mcgaskins]

I definitely will. It looks and feels very high quality, and it's clearly a flexible solution. I'm probably just going to mount it on top of the existing fuse box to keep it close to the battery and keep it simple.

 

[linuxgod]

I'm installing several scene lights on the sides of my roof rack as well as a reverse light and light bar up front. I have a switch/power panel that goes under the hood and has positive leads running from the box to go to each accessory, but I'll need to run grounds from accessory on my own. What is everyone doing for grounds on the roof rack? I was thinking of using a bus bar like this (Amazon.com: Sea Dog 426710-1 Line Buss Bar Terminal: Automotive) under the hood, and then I would run both the positive and negative wires from each accessory to roughly the same spot under the hood. Normally I would try to find a closer ground to the chassis for each accessory, but I'm not sure if there are places on the roof that are suitable. Most of the lights I'm running have a low amp draw of ~1-3 amps with the exception of the light bar which will be around 11. Here's an example of one of the scene lights:

My $0.02: I ran 4x 14ga wires in a 3/8" loom to my rack (2 pairs). One pair for the front light bar (120W), one pair for the rear camp lights (18Wx2). They're all LEDs so the power draw is relatively low. It might be possible to squeeze a third pair in a 3/8" loom but it'll be very tight. 1/2" loom will be too big for the window channel. I know, I tried.

My recommendation is to run 3x 14ga positive wires and then a 4th at 10-12ga (depending on your total load) for a common ground back to your fuse block. IMO there's not a great place to ground at the roof unless you're willing to drill or weld something - the only bolts are to the roof rack, and the fasteners have a plastic retaining clip that helps secure the metal nut so I don't think you'd get a solid ground.

Alternately you could run two 3/8" looms to the roof, one on either side of the window. That would permit 4 pairs of wires, which should be able to get you up to 6 circuits if you use 2 common grounds (one on either side).

BTW I installed the 12 circuit Blue Sea fuse box myself. Amazon.com : Blue Sea Systems ST Blade Fuse Block - 12 Circuits with Negative Bus & Cover : Fuse Block With Relay : Sports & Outdoors. For some reason the 12 circuit with cover and negative bus was cheaper than the 12 circuit without cover and/or without the negative bus. No complaints though - I wanted the negative bus, and I mounted mine in a water resistant box so I just tossed the cover.