What size wiring for 12V air compressor.

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Got Smoke?

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Ok I have a small 12V air compressor in my engine compartment that I run my air horn off. I'm guessing the fused power wire I have on it now is 12 or 14ga? Well i had to replace the main line going from my comp. to the tank to night (line got down on the exh. during the burnout comp. @ ORP) and I happened to touch the wire while it was refilling my 2 gal. tank and it was VERY hot to the touch. What size wire (w/fuse) should I be running safely on this setup? (compressor sits RIGHT next to passenger battery)
 
I think 10ga. should be good. but 12ga isnt enough.

Last night I found out that I had melted some stuff. I ran all 10ga. wire but the inline fuse block I bought only had 12ga wire. I thought it would still be heavy enough to run 12ga for the 5-6" from the battery witht he fuse block then go to 10...wrong. It had gotten so hot it melted my 30 amp fuse into the block and was starting to melt the coating off the wire.

I need to go find a 10ga fuse block now.
 
Figure 10 gage is good for 30
12 is good for 20
14 is good for 15.

Good rule of thumb. If your putting any type of length(10+) I would bump up to the next size for the run of wire, but you coudl stay with the smaller fuse size.

Example. 20' at 20 amps use the 12 gage fuse holder, but run 10 gage wire. You don't want to see more than a 5% voltage drop, accross the wire.
 
Those specs are for house wire. Auto wiring is a little different.

Your advice on bumping up the wire size for a long run is a good idea for sure.


22 5A
20 8A
18 10A
16 20A
14 40A
12 60A
10 100A
8 150A

For something like a compressor, I would run 10 gauge wire. It will draw more power the higher the pressure is while filling the tank and also the hotter the compressor gets.
 
nate said:
Those specs are for house wire. Auto wiring is a little different.

Your advice on bumping up the wire size for a long run is a good idea for sure.


22 5A
20 8A
18 10A
16 20A
14 40A
12 60A
10 100A
8 150A

For something like a compressor, I would run 10 gauge wire. It will draw more power the higher the pressure is while filling the tank and also the hotter the compressor gets.
Click to expand...

Those numbers seem a little high. Are you sure those are continuous ratings?

AWG Feet/Ohm Ohms/100ft Ampacity* mm^2 Meters/Ohm Ohms/100M

10 490.2 .204 30 2.588 149.5 .669
12 308.7 .324 20 2.053 94.1 1.06
14 193.8 .516 15 1.628 59.1 1.69
16 122.3 .818 10 1.291 37.3 2.68
18 76.8 1.30 5 1.024 23.4 4.27
20 48.1 2.08 3.3 0.812 14.7 6.82

Use this table for the resistance of copper wire
 
Maybe I am off a little. I will go out to the shop after I get home from work tomorrow morning and check on the list I have in there.
 
i would just buy an 8 gauge amp kit from walmart and run that comes with either a bus style fuse holder or an anl holder...cant go wrong with either one imo.
 
Nate your original numbers are right, but for very short distances.
I don't spec DC stuff, but I suspected that the ratings were very similar as RMS(root mean squared) voltage and current ratings deal with the average current over the 60 HZ wave cycle.
 
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