Air Compressor Tripping Breaker because of low amperage?

M Magenctek Century AC motor

Industrial Class B
Volts 120/240
Amps 15.0/7.5
Hz 60
HP SPL????
RPM 3450
Class B

Air compressor Switch
Condor 1 Phase
1 phase rating, 120volts 60Hz FLA 24 LRA 144
240 Volts 60Hz FLA 24 LRA 144
60C/75C copper wire only 10-18 AWG Torque 9lb in

Iron Force
6.25 HP
1.8 HP
28gal tank
150 Max PSI

So the compressor is tripping breaker a few seconds after running.

I have did all the trouble shooting, Good check valve, Both Caps are good, Motor was checked by AC motor tech and checked out good, good uploader valve is good. Getting 0.118 volts to the motor.

So now Im thinking an electrical problem.

Here's what I have.
Running 220 to the garage, wired to a dedicated circuit in the garage but,this circuit wire is 14-2 and at the outlet from the breaker I m only getting 110 volts.

I m now thinking I need to change this wire to a 12-2 with a double pole 20amp breaker?

I don't think Im getting enough amps to the motor from the 14-2 wire.

Comments for Air Compressor Tripping Breaker because of low amperage?

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Jan 19, 2015
wiring power
by: Doug in

I'm starting to wonder when all this was set up, and by whom...
Basically, it sounds as though this was just to get lights into the building, and maybe some small power tools. which raises:...

More questions -

The sub panel should normally have a double pole 15A main breaker, usually at the top - Does it?

The main panel feeding the sub should also have a double pole breaker - What wire gauge is running from the mains to the sub? And how long is that run? (within ten feet or so is close enough)

And yes, putting in the double breaker to your outlet will give you 220 at the outlet, and you would then change the socket (and the plug on the compressor) so no one can plug a 110 appliance into it. That means rewiring the motor for 220 per the motor plate.

NOT rewiring the motor for 220 probably means you'll need to rewire the whole thing from the mains to at least the sub, and perhaps the outlet with larger wire.

Jan 19, 2015
Comments for Air Compressor Tripping Breaker
by: JD

Doug, First off I m taking the readings off the motor tag. It reads 120/240 volts. and Amps 15.0/7.5.
When I test the voltage at all receptacles, it reads 110 volts. The wire run from the breaker to the receptacle I m using is 21 feet.
I m not clear why the motor wiring should be changed. Are you talking about the electrical cord?
So, if I used the 14AWG with the double 15amp breaker, wiring the black hot and the white neutral wires to the breaker it is going to give me 220 volts at the receptacle. Is this what your telling me?
If this is the case What double amp breaker should I be using from the house main, double 15 amp or 20 amp breaker???? Right now I have double 15 amp breaker.

I have single 15amp breakers in the sub-panel, with 220 power from the house main going to the sub-panel.

Jan 18, 2015
wiring power
by: Doug in


The amps drop in half with the double voltage, so that should make the 14AWG wire plenty big enough to handle 7.5A. You should use a 15A double breaker, but 20 is OK too, unless local code says otherwise.

You'll need to change the motor wiring of course.

BTW, are you saying that the voltage at the panel with the lights on is only 110? That makes me wonder how long and what gauge the run to the sub-panel is, and the voltage at the main panel.

Jan 17, 2015
Comments for Air Compressor Tripping Breaker
by: Anonymous

So Doug, your saying use 12 2 wire with a 20 amp double breaker?

Jan 17, 2015
wiring power
by: Doug in

The Easiest and cheapest is probably to change to 220/240. unless you want portability.

Jan 17, 2015
RE:Air Compressor Tripping Breaker
by: JD

. OK I will try and make more clear.
The motor is 120/240 volts.
100 amp house service from the street.
Have 220 volts from my house panel to the sub-panel in the detached garage. The wire in the sub-panel going out to all the receptacles is 14 2. Running only lights, receptacles and door opener with 110 volts Have one dedicated receptacle with 14 2 wire drawing 110 volts. The run from the sub-panel is about 12 feet to this receptacle, The plug on the end of the cord from the motor is stamped with "Hospital grade 15A 125V". I think someone changed out the plug.
So anyway, would running 12 2 wire and replacing the 15A breaker with a 20A breaker fix the problem? Or running 12 2 wire with a double pole 20A breaker fix the problem.
Something I did try, I ran the motor without the compressor belt on and the motor worked just fine.
I then put the belt back on and disconnected the copper line from the compressor to the tank so no air was building in the tank, and the motor also worked fine. Looking for solution.

Jan 16, 2015
wiring power
by: Doug in

Not clear what you have there...

Is the motor wired for 120? or 240?

If 120, then depending on the run footage, larger wire is in order.

Having only 110 at the panel is not uncommon, but perhaps the power company can bring that up, if that's the usual voltage at your location.

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circuit pops only at work. works fine at home

by Cheryl Casanova
(Vacaville, Ca, USA)

At home I have no issues. When I use it at work is when the issue happens. It will allow the tank to completely fill up but when I try to use the compressor it blows the circuit.
I would think, based on what you have written, that your compressor power supply at work is not as reliable as that at the office.

What else is on the power circuit at work that is supplying the air compressor, and running and pulling power from the circuit as your compressor is running.

And, what is the amperage of the breaker of your power supply at home, versus the amperage of the breaker of the compressor power supply at work?


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