ARB Compressor Extended Harness Concern

I purchased an aftermarket extended wiring harness for my ARB single compressor so that I can mount it in the driver’s rear bed box. This particular harness includes extra wiring so that a second switch can be added to the bed box in addition to the cabin switch that comes with the compressor.

Here’s my concern: The power and ground on the original ARB harness appear to be 10awg. Those will connect directly to the battery. The end of the ARB harness connects into the extension, which runs 17ft or so to the bed. The power and ground wires in the extension are a smaller gauge - I’m guessing 12awg. Is this acceptable?

I am not great with electrical, but all my knowledge says that greater length requires larger gauge wires (or at least the same.) The instructions from ARB state:

“If any of the wires require extra length to reach the battery then splice in an extension using ONLY wire that is of the same gage or bigger than the wire being lengthened.”

Interestingly enough, the largest gauge wire in the extended harness (10awg,) is a dedicated power wire for the bed switch that runs all the way back to the battery with a 10amp inline fuse. Why this wire would be a larger gauge than the compressor power wire is baffling to me.

I’m hoping I can learn something here. Thanks for the help.

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Ya amps over distance will determine gauge. I don’t recall what amps the compressor draws. Where did you purchase the extended harness? Is it am ARB harness?

 

Might wanna move the fuse closer to the battery too. That was one thing that bothered me with their regular harness

 

The harness is aftermarket from All-Pro Off-Road. The ARB manual states the current draw under load is 23A.

If I plug that into one of the online calculators, with the return to ground included, it comes up around 4-6awg. I don’t know of anyone who has run wires nearly that big for this mod.

 

I completely agree.

 

So I ran 10 awg for 15amps for a fridge. 23A can get away with 6-8awg. I would contact all pro.

 

Thanks. I will contact them for sure. I’m doing a little bit more research before then so I can understand what’s going on.

 

The description states:

“Wiring is appropriately sized for voltage and amperage requirements for the corresponding compressor model. Only correct automotive grade wiring is used throughout.”

I even called before buying to ask about the gauge of wire. The tech didn’t know the exact sizes, but said it had been vetted.

I don’t know what to think here.

 

Means nothing to me. Show me the awg. I saw that on their website and was like, ya not.

 

My plan is 4 gauge to the rear but I have a dual.

For a single I might go 6 gauge.

There is a really cool fuse box for the taillight cavity made by @switch which can help convert the large gauge to 10 gauge to feed the compressor.

The extension harnesses seem insufficient to me.

 

Haha. Chatgpt says 8g.

 

I was just looking at Blue Sea for a small distribution block to go from a 6 to the 10awg harness. I also don’t understand how you’re not getting an unacceptable voltage drop from these harnesses.

 

That does sound about right for 17ft, but I think you’re also supposed to include the distance to ground. ARB recommends grounding directly to the battery which I read is better for a high current circuit.

 

https://www.tacomaworld.com/threads...r-behind-the-taillights.786610/#post-28145684

 

I would be more comfortable if it was 10awg at that length but even better if it was 8awg. I ran 10 awg gxl for a viair that would pull close to 30amps at basically a 12ft run.

But you really need to confirm the wire gauge. GXL and TXL automotive wire for example have super thin jackets and look smaller than cheaper wire with fatter insulation. Eyeballing it isn’t entirely accurate. If they say it’s 10 i wouldn’t even worry about it @~23 peak amps loaded.

edit: I also ground straight to chassis. But I have upgraded battery and engine grounds and don’t buy into running all accessories under the sun back to the battery. I only really do that for radios.