Why is my ARB twin compressor repeatedly tripping a 150 amp breaker?

[Vinman]

ARB twin mounted inside the Jeep.
I have a dedicated pair of 4 gauge wires feeding a terminal block located in the back of the Jeep and the ARB is using that block for power with the ARB harness with a pair of 40 amp fuses.
The positive side of the 4 ga. wires has the 150 amp breaker located about 6” from the battery and after airing up a couple of tires it starts tripping and I constantly have to reset it to finish airing up. I initially thought I had a bad breaker so changed it out and the new one does the same thing.
The compressor is in a well ventilated area with sufficient air circulation and doesn’t appear to be getting hot prior to tripping. Considering people run these in the engine compartment in triple digit temps I don’t see how it could be too hot.
What boggles my mind is why the 150 amp breaker is tripping before the 40 amp fuses blow.

Anybody have any insight?

 

[Wheeler]

Breakers are designed to trip when a certain level of heat is reached. A direct short is the fastest way to reach that point and cause a breaker to trip.

Something is causing the breaker to heat up. Usually this is found at a loose connection. While your connections may be good the terminals you attached your wires to may be bad or even the compressor itself.

If you can isolate the issue it would help you troubleshoot. Remove the terminal block or better yet , hook the compressor directly to the battery with the breaker inline and verify the compressor is good. Next remove the terminal block and running off your #4 conductors and the fuse block would be another good step.

ETA: if the breaker is tripping before the fuses blow I’d take a good, hard look at the terminal block, the connections there, the breaker, and your leads running from the pump to the terminal block.

 

[Jerry Bransford]

Once a breaker starts tripping it rarely keeps its spec'd amperage capacity. If that breaker was tripping for a good reason at some point I doubt it still has a 150 amp capacity.

 

[Vinman]

Thanks for the suggestions, I’ll check all connections and bypass the terminal block then give it a go. If the breaker still trips I think I’ll just replace it with a fuse. I’m about 99% certain the compressor is fine as it’s less than a year old and has been mounted inside since.
I also picked up some pure copper wire to replace the copper coated aluminum wire currently feeding the terminal block, although can’t see how that would change anything.

 

[Wheeler]

The Aluminum wire might be the issue. It doesn’t carry the same load that an equivalent sized copper wire will carry nor does it make as solid a connection under a mechanical lug.