Wiring gauge and fuses

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1

Ok, I’ve read all I can and still am mystified as to what I should do with my compressors.

I have Dual ViAir 480c compressors. They didn’t come with wire. The leads on the compressors look about 12 guage. I have read in the forums that you should use 10 guage wire from the battery.

Some people say wire the ground directly to the battery too, and some don’t.

The salesman at HB told me to use a 40 amp in line fuse with this set up but Hornblasters Wiring/Plumbing Schematic says to use a 60A fuse. Inasmuch as each compressor has a 19 Amp draw, I assume this is a typo and I should use the 40 Amp fuse. Additionally, is that for each compressor, or should I wire them seperately? Would both compressors running from a single 10 guage wire and one in line 40 Amp fuse work properly?

So I guess my questions are:

  1. What guage wire to use
  2. Do I run a separate power source to each compressor or wire them together.
  3. Depending on the answer to #2, what amp fuse do I use with the wires I have.
  4. Do I really have to run a ground wire back to the battery or can I just grind down the frame and ground her right there?

Caveat on wire guage: I have the compressors behind the back bumper of my pick up, so the distance is pretty far.:confused:

2

I am doing an install in the same location. Great questions and much needed answers for both of us. We will have to see what the experts say.

3

I forgot what I used.

  1. It was around 10 gauge maybe a little larger. (bigger is better)
  2. I would run them separate. If you did run them together, you would need a much larger gauge wire.
  3. Ill have to look, cant remember off the top of my head.
  4. No, ground it wherever you have a solid place on the frame
    ------- Dry location, sand it down the frame a little to so there isnt any paint. I also grounded everything to one point. Just make sure its a solid ground.
4

38 amps on a single 10ga run is pretty borderline for your 20+ ft run.
The absolute max fuse for 10ga is 50 amps IMO - and a lot more comfortable would be 40 amps…so that doesn’t leave any wriggle room. You can google wire gauge chart…

Do you have seperate relays or a dual unit? It could make a difference what is easier - 2 10ga runs with 30 amp fuses or a single 8ga with 60 amp. If you do a single run and split it - you have to fuse the smaller gauge wires after the split.

A good bare metal ground is fine.

5

Thanks for the help guys. HB forgot to throw in the wiring kit, so they sent me one (fashtest shipping of any company I’ve ever dealt with). It looks like two 20ft runs of 10 gauge wire with 35 amp fuses. I will wire the compressors separately to the battery.

I’ll Google the fuses as you recommended and try to keep the wires as short as possible. I used a grinder to get a good ground on the frame, so from what you said, I’m good to go.

I plan to run the intakes up hugh under the brake lights where it is dry. If that doesn’t work out, I will use a dishwasher vent and some PVC to keep them dry.

I’ll be raising hell this weekend, woot!

6

I never recommend grounding any compressor to the chassis because a copper cable conducts a lot better than a steel frame.

7

I hear ya. This is debated a lot in the car audio world. I won’t get into all that, but let’s just say I do both…

8

Copper is a better conductor than steal but when you take into the huge mass of the steal frame that makes it a Much better conductor than any copper wire that you will use on your vehicle. Also the NEC rates a 10 awg copper conductor at 40 amps but I would never go more than 30. Remember E=IxR The higher the amps the lower the voltage.

9

I’m no electrical engineer but after 10 years of experience I’ve found our customers have less low voltage issues by grounding our cable to a battery. I’ve even had customers whose low voltage problems disappeared after taking our advice.

10

For the steel frame to be an affective ground with high amp draw accessories you need to upgrade the stock wiring. This is very common in the car audio world and is called “The Big 3”. That means adding 1)a positive lead from the alternator to the battery, 2)a negative lead from the engine block to the frame, 3)a negative lead from the battery to the frame. Stock battery cables are usually about 6ga so adding 4ga or 1/0 leads helps tremendously.

Not advocating one or the other, but upgrading the Big 3 somewhat levels the playing field.

11

I run a 4ga wire from the battery to a distribution block located under the truck (I keep poping fuses) right now… I’m going to swap that out for 10ga wiring for each and put them both on an 80 amp relay and hook the pressure switch to it…