circuit breaker

ok for some reason now for the past week my circuit breaker for my compressors has been switching off. when i checked it the wires seemed like they were getting hot but not sure if it was too hot. im running 3 thomas compressors, 4 guage wire and a 140 circuit breaker. any thoughts on why it could be doing this?

Are you running relays for our pressure switches? Maybe the relays are fried. Is the insulation on any wires cut up? Could be shorting out somewhere. That's a big breaker for only 3 compressors.

sorry man im kinda new to all of this. not sure if there are relays for the pressure switches or not. where would i find those? ill have to check the wire and see its messed up or not. what size breaker do you recommend for 3 compressors? thanks for the help.

check where the wiring goes from the compressor. The positive(red) wire from the compressor should go to a relay. From the relay there are 3 more wires. Of of those wires go to your pressure switch. The pressure switch is usually mounted on the air tank or off your compressor. Thomas compressors are usually between 20 and 30 amps. So the max amps on the breaker for 3 compressors should be 90amps. Putting a larger breaker might cause a fire and you don't want that. Any more questions just IM me or email me.

this is what a relay looks like

a pressure switch looks like this

dont forget the square d style of pressure switch.

ok heres what i found. my pressure switch is mounted after the tank. there are two wire, one is ground and the other runs to a round thing by the compressors. my power wire also mounts to this round this and all 3 of my compressors are wired up to a separate terminal on it. any clue what this thing is. if it will help ill try to get pics of it. i got kinda worried today too cause i turned my compressors on and popped my hood and there was smoke coming from the breaker.....so needless to say i wont be driving my truck till i get this fixed. i am glad i looked under my truck too cause i think its time to take the bed off and fix somethings(the a crossmember that is rubbing the driveshaft and not letting the truck sit all the way down). thanks for all the help.

can you take a pic of it to show us?

ya ill get some pics of it tommorow and post them up.

I have a question if anyone can help. I have a blowjax dc5000 compressor (sucks) but anyways my relay always acts funny, it will work and sometimes it will not. I dont have a pressure switch, instead i replaced it with a switch in the cab. I have replaced the relay many of times. Dose anyone know where I can get a heavy duty ralay, I have been using just a regular (starter relay, or old ford style relay. When the relay acts up i usually just jump it with a short wire, then after I take the wire off the thing it will work fine?

Bosch makes the best relays.

the guy in the first post needs to rewire the whole thing. all the compressors need a seperate relay, not running thru a pressure switch.

the relays need to be set up to ground the system. the pressure switch will ground the relay and kick on the compressors.

this means, from the compressor, run the red wire to the relay, the other side of the relay (power) to the battery. then the pressure switch to the switched side of the relay.

if you run a compressor power wire thru a pressure switch, even a good one, you are asking to be broke down some time or other.

the relay is the best and actually easiest way to do this.