Wiring Circuit for a Roof Rack?

[60seriesguy]

One of the interesting features of expedition rigs on this forum is the high-level of execution of electrical modifications. While everyone should strive for a top-notch design and installation, it's scarily common to see hacked-up electrical jobs on other forums, mostly on trailered rigs but sometimes on daily drivers as well. For folks that depend on their rig's reliability in remote locations, that is not an option.

As I embark on my first new buildup in twenty years, I'd like to tap into your collective wisdom and get some advice on the best way to *safely* and *efficiently* wire up my roof rack. Below are some details:

- INTI 3/4 length expedition rack, originally designed for an FJ60 but modified to fit a 100 series
- Four front-facing lights, Hella 500s. Two have flood pattern (outside), two have driving pattern (inside). Mounted in pairs on the front of the rack
- Two flood pattern tractor lights, mounted on the rack between the front and rear doors, one on each side
- Two flood pattern tractor lights, mounts on the rear of the rack
- *If possible*, there is one more accessory I'd like to connect to the roof rack, assume its draw is similar to one light

Ideally, I'd like to have only two switches (the 100 Series is challenged for extra switch locations), one for the front four, one for the other four (with the option of a third switch for the mystery accessory). *If possible*, I'd like to have an additional (concealed) rack-mounted switch that could turn on the tractor lights from the outside of the truck, but that's not a show-stopper.

I have a waterproof junction box that will be mounted to the rack close to where the wires will come up to it and will house relays (and possibly that switch). I'm comfortable with electrical installations and will use marine-quality connectors, soldering and shrink-tubing and dielectric grease. I also plan to run all wiring through a "loom" and secure it to the roof rack. I only run the roof rack on trips, so the plan is to have everything securely mounted to it and then have only a short pigtail with a quick-disconnect to connect it to the truck.I have already solved the issue of how to run wires (not sure on how many) up to the rack cleanly and securely, so that's not an issue.

I am not 100% sure of how to design the circuit to maximize the efficient use of the lights, minimize issues. I'd love to hear some suggestions.

Also, is 10 ga. wire overkill for this application?

Thoughts? Suggestions? Comments? Graphic depictions?

 

[ntsqd]

Henry,
My advice with regards to if a 10 gauge is big enough would be to point you to one of the 12VDC boat publications. Those that I've looked at had a nomograph (sp?) or a chart for figuring out how big a wire for the total draw over the given distance. I have an old Anchor catalog with this chart, but I don't know where you might find a copy or I'd just suggest that.
Two books on West Marine's page that may or may not be of value:
12 Volt Doctor's Practical Handbook

12 Volt Bible 2nd Edition

Without knowing who you use for wiring supplies I'll suggest looking at these pages:
Common Components:
Del City Wire

Waytek Wire

Tow Truck Supplier:
AW Direct

Marine Electrical:
West Marine

Electrical - Electronics Suppliers:
Allied Electrical

Newark

Mouser

Digi-Key

I'll venture that if one of these companies doesn't have it, it may not exist.

 

[dieselcruiserhead]

The big thing is how you want to route the wiring. If you have a bunch of wires heading up to the rack (ie - relays in a box on the rack) then it will be cumbersome with, IMO, limited benefit from the wires being shorter with the relays actually on the rack. This will change things from 3 or 4 wires to 10 or more to the rack because the switch and grounds and voltage feed wires must now all be routed to the rack.

What I would two is two 30 amp relays under the hood. Then three wires total going to the rack. Because you want to turn on all four at once, this simplifies things. Three wires total. One to front (fat gauge, 10 or 12 gauge because of the high draw), one wire to the rear (medium-fat gauge, like 14 gauge will be fine), and a common ground.

If you decided you do want to seperate the front lights with independent switches then add one switch and one more relay and one more wire to the rack. Still super clean.

Then use a water proof harness of some sort. If it were me i would run the harness from the rear hatch so when you remove the rack, you can take the wiring and tuck it into the panel, like a trailer harness that comes out a rear panel. 4 wires should go past the molding and through the gap of a rear hatch when closed easily. Then the rack and its options are plug and play and easy to remove or easy to set up...

If you add antennas to the rack versus a bumper or something, plan this too and possibly try to keep together for cleanliness and ease of removing or installing the rack as well...

 

[60seriesguy]

Thanks for the tips, guys. I've already sourced a lot of the components (left over from the non-completed projects for the previous build) and I'm well versed with several of those catalogs, including Waytek.

I am using the snorkel to route the wire harness up, so I'm not concerned about how much wiring goes up to the rack. I've considered other methods and have used several of them in the past, but I think this is the cleanest given the INTI rack's design. I'm not drilling through the roof of the truck and in my experience, using doors/hatches to run wires eventually damages the weather-stripping and causes leaks.

I can very easily mount the relays under the hood, I just thought it would be cleaner to have the rack-specific ones with the rack, since I'm also having to wire a bunch of other accessories into the engine compartment (along with a secondary fusebox).

Keep it coming, folks, one of my goals (however unrealistic) for this project is "do it right, do it once". I have the luxury of time and the budget allocated for this stage of the buildup is decent (but certainly not unlimited!). I'm also pretty comfortable with electrical work on the truck, too, just trying to figure out what options are out there that I have not considered and hoping to capitalize on your collective experience.

 

[ntsqd]

FWIW, I like the idea of the relays up close to the draws. The main reason being that the control wires can be tiny, particularly if they are switched to ground. Then the only wire with a pinch or damage worry is the sole power wire. Were something like that to happen to a control wire(s) it would only turn on what ever relay it controlled.

With the relays up top there will be only one more wire than if they were under the hood, and only that one will be carrying any significant current. With the relays under the hood every wire will have significant current. There really won't be any difference in the total length of wire used vs. relays up, but those will all be larger wires.

The Allied/Mouser/Newark/etc. links should all have lower tech versions of the mil-spec "Cannon Plug" type plug/socket assembly that might be perfectly appropriate for the actual D/C at the snorkel. I have used such a plug with a bulkhead socket on a project here at work.

 

[\\'anderer]

here is a link to a wire gauge/amp capacity chart, not the most detailed, but a good chart nevertheless.

http://www.the12volt.com/info/recwirsz.asp

 

[Sgt Grunt]

Henry,

I recently mounted 4 Hella 4000's on my Inti with a disconnect so I can remove the rack. It all turned out pretty good, I used 4 x 12 guage wire and ran a total of about 25 feet, Hella relays, factory Toyota switches plus the waterproof connector. I ended up running it through the snorkle then up the rain gutter to the first foot of the rack.

I can shoot you some detailed pictures if you want...

 

[Mlachica]

Personally I'd locate the relays under the hood. There will be fewer wires going to the rack and shorter wire runs. Shorter runs = lesser chance for chaeffing and shorts. Much better IMHO.

for the secret switch. For the inside get a three position switch. on-off-on. which would be wired on-off-outside switch. So you could turn the lights on from in the cab, then when you're at camp you can switch to the other on position to control the lights through the rack switch.

 

[davegonz]

Now that I have a rack on the Princess, I also want to add lights and need a plan on how to do it. Are you going to run the harness through the snorkel or behind it somehow?

 

[tacojosh]

Relays and switch panel

Well, I started the same way, just wanted something sano and dependable when out on the trails. After 2 years of lighting, wiring and keeping it as clean as I could. I stumbled across a guy who had the answer to all my relay/switching enigmas!
Every day I get into my Tacoma and look at my new switch panel and relay power distribution system, and I say, where was this when I needed it it years ago!
Man am I ever happy now! I met John on the trails (which I really like other than the shows) and he showed me his vehicle and what he had to offer. He asked if I would be willing to test his products. I was not sure until I actually saw the system he had developed! I said, "I'm in!"

 

[benedmonson]

Would love to know how to get in touch with this guy as I just installed my new roof rack and lights this week and need to wire everything, this stuff looks great!!

Ben

Well, I started the same way, just wanted something sano and dependable when out on the trails. After 2 years of lighting, wiring and keeping it as clean as I could. I stumbled across a guy who had the answer to all my relay/switching enigmas!
Every day I get into my Tacoma and look at my new switch panel and relay power distribution system, and I say, where was this when I needed it it years ago!
Man am I ever happy now! I met John on the trails (which I really like other than the shows) and he showed me his vehicle and what he had to offer. He asked if I would be willing to test his products. I was not sure until I actually saw the system he had developed! I said, "I'm in!"

 

[GulfShoresFJ60]

Would love to know how to get in touch with this guy as I just installed my new roof rack and lights this week and need to wire everything, this stuff looks great!!

Ben

www.4x4s-pod.com

That is link from this thread here with information he provided on this same system.