Roof Rack Wiring Advice Needed

[varun bhargava]

First timer here. I need some advice about the correct way of running wires up to my roof rack. I am debating between:

1. running a single ground cable (ground the roof rack and create a distribution point
2. running a ground per accessory/circuit
3. run three ground cables. One for the lights, one for the aux power and one for solar

Any red flags w/the diagrams below?

Total Load

• All roof rack lights (~4A = 8 x .4A Stedi lights across 3 circuits)
• Aux 12v - max 10A (future-proofing)
• Solar - max 20A (future-proofing)

Considerations:

• I live in WI so the climate can be harsh
• I'd like to add solar at some point. It seems like 20 amps should be more than enough. Thoughts?

Route: Tailgate --> roof rack

Wiring Diagram:

KC = Cyclone V2 Rock Lights for Rock, Underhood and Tailgate Lights (.42A each) - Cyclone V2 LED - Single Light - https://www.kchilites.com/cyclone-v2-cyclone-v2-led-single-light.html
S = Stedi Roof Rack Rock Lights (.4A each) - Surface 5700K LED Rock Light - https://www.stedi.com.au/surface-single-white-led-rock-light.html
BD = Baja Designs LP9 Pro and Squadron Pro lights

Thanks in advance.

 

[doru]

You can come to the rack using a common ground (sized according to the total load plus some headroom) and have a distribution box for the lights with one ground cable to each, but do not ground the rack itself. The rack is outside and all the grounding points will go bad in no time if not protected inside water sealed enclosures.

 

[grinchy]

I was able to put 2, 12ga silicone sheath wires up under the front trim of the windshield. I think one 10ga would fit if you went to one wire on each side, maybe a flat 8 ga, if there is such a thing.

Remember you'll need a bunch of small (22ga would do) wires to run from your switching solution up to actually turn the stuff on and off. Or you can run a bluetooth relay box up there, that was my plan, though I haven't done it yet.

 

[Julian73]

I have a similar setup, including future proofing. I ran a dedicated solar feed and Gnd using 8g cables (for up to 30 amp) and bundled And (2x12g cables for) all roof lights (4 Rigid scene and 2 Baja rear flood) along with a 10 amp aux power supply (future proofing). Run up through rear hatch to roof. One large single ground for all circuits would be fine if not for lack of space and bending constraints.

 

[Fisher23]

I'd suggest Single "enclosed ground bar".
You can run them up the cannel of the rear cargo hatch.
Solar same path later, or you can pre-run the 2 wires now.

 

[varun bhargava]

I have a similar setup, including future proofing. I ran a dedicated solar feed and Gnd using 8g cables (for up to 30 amp) and bundled And (2x12g cables for) all roof lights (4 Rigid scene and 2 Baja rear flood) along with a 10 amp aux power supply (future proofing). Run up through rear hatch to roof. One large single ground for all circuits would be fine if not for lack of space and bending constraints.

I have noticed that most people run 8g cable even though the max amp range most panels I have seen are below 15A. Is this due to future-proofing or something else? Are panels considered critical or non-critical?

Thanks in advance.

 

[Julian73]

My calculations used 20 amp nominal, 25 amp continuous (25% load factor) and 29 amp peak .. may be conservative. Assumed 47.5 ft wire run, including and back to a chassis point, not all teh way to teh battery.

Assumed a semi-critical circuit so aimed (and slightly missed < 3% voltage drop). At 25 amps continuous, my voltage drop is 3.2% using an 8AWG. Good for a 41 amperage max assuming passing through hot engine bay, in a 6+ cable bundle. a 10 g good for about 30 amps would have pushed drop to 10.2%

 

[lx200inAR]

I have noticed that most people run 8g cable even though the max amp range most panels I have seen are below 15A. Is this due to future-proofing or something else? Are panels considered critical or non-critical?

Thanks in advance.

If you are paralleling 2 panels, then you'd require 30A. You could optionally run in series, which is better for your wiring, but charge controller and avoiding shading issues may keep that from being ideal or possible.

 

[619TOY]

I prefer to use a matched pair of wires per circuit and do my distribution inside the vehicle. So kinda sounds a little like #2 & a little like #3. I ran 2 12AWG wires for my solar panel, but I think maybe some of you are running substantially more solar than me or you're overachievers. In full sun, my 80 watt panel puts out about 20 volts, so about 4 amps. Sure once the DC-DC converter drops it down, the current will go up, but not that much.

 

[CharlieS]

I only had a light bar, so I ran power and ground up under the side channel of the windshield on the passenger side (closest to my switchpros). You could do the same on both sides and get quite a few wires up there, especially if you go with small gauge like the switchpros load wires. I used a much heavier gauge wire because I had it handy (Ancor, tinned, sheathed marine grade wire).

 

[thefourthchime]

I was able to put 2, 12ga silicone sheath wires up under the front trim of the windshield. I think one 10ga would fit if you went to one wire on each side, maybe a flat 8 ga, if there is such a thing.

Remember you'll need a bunch of small (22ga would do) wires to run from your switching solution up to actually turn the stuff on and off. Or you can run a bluetooth relay box up there, that was my plan, though I haven't done it yet.

I'm looking to do the same, how do you get them to stay there? I know people use RTV, but I would like something that's easier to remove. Maybe double-sided tape, or find a tube that will jam in there snuggly?

 

[TheComedian]

I drilled a hole in the roof, installed a cable grommet for boats, and then ran the cables on the driver's side over the B-pillar….

 

[Julian73]

I only had a light bar, so I ran power and ground up under the side channel of the windshield on the passenger side (closest to my switchpros). You could do the same on both sides and get quite a few wires up there, especially if you go with small gauge like the switchpros load wires. I used a much heavier gauge wire because I had it handy (Ancor, tinned, sheathed marine grade wire).

You could try this to protect wires up the windshield pillar.

https://www.frontrunneroutfitters.com/en/us/universal-wire-hider-ligh226.html