Air compressor blowing circuit breaker

[Mikail Khan]

Clip on ampmeters are cheap and help with troubleshooting. Will tell you actual current draw.

MK

[mark mcfarlane]

The unloader is your 1st place to look. They get "sticky" (and a bit later just stop working altogether). They are not difficult to replace.

Thanks Lisa Is this the unloader? It does actuate when the compressor shuts off.

unloader.jpg

Does one typically just replace the little brass fitting with the valve, or the actuating arm assembly which is part of the pressure switch? Unfortunately my manual and IR's web site don't even show this valve as one of the parts.

[Tom M King]

The first thing I would try is to lube the bearings/bushings on the motor, whether they are designed to be lubed, or not. I have a motor on a wet tile saw, that was doing the same thing, that has kept working for several years, so far.

[Rob Charles]

Mark; What I was referring to is the part that you have correctly identified as the Unloader in the photo responding to Lisa's post. Typically, they work so that, when the pressure switch turn off, the lever moves and pushes in a one way check valve releasing the pressure in the tubing between the compressor pump head and the tank check valve. A small amount of air is released. When the pump turns on, the lever moves closing the valve (unloader) until the switch turns is back off again. Probably the easiest way to check it is, the next time you find the breaker tripped, check to unloader to verify the pressure was released.

Depending upon your switch configuration, the contacts may not be visible or accessible. I was unable to tell from your photos.

[Bill Dufour]

You need to convert to 240 volts or pull new 120 volt wire to carry 30 amps at 120 V. The breaker and wire is fine you are just at the limits.
How far from the service entrance does the wire run? Over fifty feet can cause a noticeable volt drop under load and a corresponding amp increase.
Bill D

[mark mcfarlane]

Thanks Rob I’ll check this valve the next time I throw a breaker. That’s a great idea.

[mark mcfarlane]

Thanks Bill. The service panel is about 7 feet away from the outlet where the compressor is plugged in. Add 5 foot to the ceiling and 5 foot back down to the outlet you’re looking at about 18’ for the wire.

[Mike Henderson]

I had that same problem when I had my compressor on 120 volts. I changed it to 240 volts and never had another problem.

Mike

[John K Jordan]

Thanks Rob I’ll check this valve the next time I throw a breaker. That’s a great idea.

I didn't make it through all the posts so maybe already mentioned - occasionally a breakers can become "weak" and need to be replaced. But I also vote for checking the actual amperage with a meter. And check the voltage to that receptacle and to the shop itself. If the voltage is low at times for some reason the motor will draw higher current.

I hope you are turning off/disconnecting the air compressor when leaving the shop. Shops have burned to the ground when a break in an air line caused a compressor to run continuously.

JKJ

[Bill Dufour]

Thanks Bill. The service panel is about 7 feet away from the outlet where the compressor is plugged in. Add 5 foot to the ceiling and 5 foot back down to the outlet you’re looking at about 18’ for the wire.

36' is nothing to the source of unlimited amps so voltage drop is not a problem due to long wire runs.
Bill D

[Osvaldo Cristo]

IR offers these possibilities for "Motor overload trips or draws excessive current", I guess I should start by checking the belt tension:

1. Lubricant viscosity too high.
2. Improper line voltage.
3. Wiring or electric service panel too small.
4. Poor contact on motor terminals or starter connections.
5. Improper starter overload heaters.
6. Poor power regulation (unbalanced line).
7. Drive belts too tight or misaligned.
8. Compressor valves leaky, broken, carbonized or loose.
9. Cylinder(s) or piston(s) scratched, worn or scored.
10.Connecting rod, piston pin or crankpin bearings worn or
scored.
11.Defective ball bearings on crankshaft or motor shaft.
12.Leaking check valve or check valve seat blown out.
13.Ambient temperature too low.
14.Bad motor.

Good list!

I add check the start up capacitor as sometimes when it is defective it can result in an atypically high start up current and by consequence blowing your surge protection.

[Tom Bender]

The grid provides 120 volts plus or minus 10%. Normally it is much closer than 10% but you may be in a place that is up there. And in your building you have some loads that can pull it down a bit more. This includes motors starting, electric clothes dryers, electric heat, electric water heater. Since your compressor is at the limit for your circuit breaker you may be experiencing bad timing vs available voltage when it starts.

[Edward Dyas]

I have a slow leak somewhere in my air line plumbing (which I possibly should not have installed in the walls...), This causes my air compressor to cycle maybe once or twice a day to refill the circular network of air lines.

Every few days the compressor throws the 20 amp dedicated 120V circuit breaker. Compressor is an IR Garage Mate, 2HP, 20 gallon, about 2 years old. Air filters are clean, pump oil is maybe 2mm above the 'fill bubble', i.e. a tad overfilled.

Any ideas why the breaker is getting thrown?

Thanks,

An air compressor draws a lot of power at startup. If you are a long distance from the breaker it draws even more. Also if your shop is cold it makes it all the harder to start. I have a large commercial compressor I just have to turn off when the temperature is in the teens or below.

[Bill Dufour]

An air compressor draws a lot of power at startup. If you are a long distance from the breaker it draws even more. Also if your shop is cold it makes it all the harder to start. I have a large commercial compressor I just have to turn off when the temperature is in the teens or below.

Location? I am guessing you are talking fahrenheiht?

[John K Jordan]

Location? I am guessing you are talking fahrenheiht?

Just an idea - if more people would put their location in their profiles lots of the conversations here would be clearer or at least simplified. Those in the witness protection program or hiding from the authorities or creditors could leave off the city name or list something like "Southwest US"

JKJ