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Air compressor blows breaker.


Dozer

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Ive had this compressor for about 6 or 7 years and have always had problems with it blowing breakers. Ive had it in a couple garages and only have problems in about half of them. The garage I am in now is really bad, seems like it blows the breaker about everyother time it kicks on. It is a big compressor with a big cord and I think it just draws too much power for a 20amp breaker. Is is the only thing on that breaker. Is there any way to prevent this? I was thinking it might help to run 10ga wire from the breaker to the outlet (I think it is only 12ga now). Anything else I could try to help eliminate this?

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I had the same problem especially when it got cold out and I replaced my oil with tranny fluid and that took care of it, my CNC teacher is a very intelligent guy and he tipped me off about this idea, and the thing has never kicked out the breaker since or try putting one size bigger breaker in. Good Luck

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Your garage should have 12 wire in it already. If not, you could run new wires. Don't use a bigger breaker than the wire is made for. Could result in a fire.

Some breakers are just weak, but compressors do take alot of power. Could also try draining the tank before you start it. Compressors start easier after warm and with no air in them. If you have to, let the air run out of it while it is running for about 30 seconds to a minute to let the motor warm up.

We run into this often with our compressors for work.

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I had the same problem especially when it got cold out and I replaced my oil with tranny fluid and that took care of it, my CNC teacher is a very intelligent guy and he tipped me off about this idea, and the thing has never kicked out the breaker since or try putting one size bigger breaker in. Good Luck

Might have to try the tranny fluid. Do they make a 25amp or 30amp breaker? ( I know that simply repacing a 20amp breaker with a 25amp isnt the "right thing" to do and is going to violate all kinds of codes but Im just brainstorming here)

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Your garage should have 12 wire in it already. If not, you could run new wires. Don't use a bigger breaker than the wire is made for. Could result in a fire.

Some breakers are just weak, but compressors do take alot of power. Could also try draining the tank before you start it. Compressors start easier after warm and with no air in them. If you have to, let the air run out of it while it is running for about 30 seconds to a minute to let the motor warm up.

We run into this often with our compressors for work.

I guess I dont know what gauge it is, havent checked that out yet. How big of a breaker can a guy run on a 10 or 12 ga wire? I dont use it enough to let it warm up before I use it. I like to just leave it one all the time so it is full when I need it. Maybe I should buy a "quality" 20amp breaker and try that?

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One of the sparky's here could tell you for sure. The wire will say on it whether it is 14 wire or 12 wire. 14 wire is usually on 15 amp and 12 wire on 20 amp.

A 20 amp breaker should hold just fine especially if you only have one thing plugged in on that circuit.

I would wait and see what the electricians here say and maybe try a new breaker, wire, and/or outlet.

You will also have to see what kind of breaker you need. I know some are different than others.

I have some older 15 amp breakers in my house that hold better than any new 20 amp I have used.

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Are you using an extension cord? If so that could be the problem right there. If you have to use an extension cord keep it as short as possible and 12 gauge. Ideally in a garage it shouldn't be on an extension cord anyway.

You'll have to check to see what gauge wire you have to your receptacle. In a garage I believe 12 gauge is code. Look for the amp draw on the motor, then figure if is 12 gauge enough for the amp draw.

If your not using an extension cord and you do have 12 gauge and you good with your amp draw then I'd look for an issue with the compressor.

When it shuts off it should dump air, you'll hear it. Its taking a load off the motor/compressor for the next start up.

Most compressors come new with break in oil. I wonder how many of these never get replaced after break in? I'd replace the oil next. If this garage is unheated that will compound the problem. If compatible with your oil type a synthetic air compressor oil could only help.

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Your circuit breaker is tripping because the branch circuit that it is protecting is drawing too much current. Using 10ga. wire won't matter. The 12ga. wire is sized to handle the 20A load. With the information I see so far, I'd say there's nothing wrong with your circuit or circuit breaker. It's doing what it is designed to do.

Whenever a motor turns on, there is a momentary inrush of high current until the motor gets up to running speed. Normally, this lasts for such a short time period that a circuit breaker will not overload. Circuit breakers are designed with some time delay to prevent nuisance trips due to motor loads. However, if the load on the motor has increased, the motor will demand more current from the circuit than usual. This high current demand could overload the circuit breaker if it stays too high for too long. So what can cause increased load?

If the oil in your compressor is getting old, is too heavy, or is cold it will increase the load on the motor. In a worse case scenario it could be loading down the motor enough to overload the circuit breaker.

The control switch should be set to turn the motor off at some set point. If your compressor set point is set too high per the compressor specifications, this could add excessive load on the motor. The higher you build up the air pressure in the tank, the more load you are putting on the motor.

The control switch should also be set to turn the compressor motor on again when the pressure drops below a certain set point. This too shouldn't be too high. Remember, the higher the pressure in the tank the harder the motor has to work. Imagine how hard it is for the motor to start up with the tank under pressure already. This setting too should not be higher than specifications.

Another possible cause would be a motor bushing that is getting dry, which can also increase the load on the motor by adding drag. For this reason some motors have oil caps for lubricating the shaft bushings. If yours does, use a light machine oil to lubricate it. It only takes a couple drops so don't over oil.

I assume the motor is the original motor but if it has ever been changed and the replacement has a lower horsepower rating than required, it will not be able to handle the load and this may also cause an increase in current demand.

Hope this helps.

Bob

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There should be a rating tag on the compressor motor. Start amp/run amp?

You need to do a load test with a AMP gage to see how much load is on the wire.

Test at start up. Than test running amps. If test shows the draw is higher then

the motor's rating tag you may need a new motor.

Or all the variables that BobT suggested. (good info by the way) It could be something as simple as the belt being to tight.

Disclaimer: I am in no an expert, at anything. anything I say is my own opinion

and/or observation, and should never be regarded as fact, unless otherwise stated.

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One other thing you should check is the relief valve. If that is not working, it does not relieve the head pressure from the compressor cylinder. When it tries to restart its very difficult for the motor to get it started and spikes the amperage load momentarily. When the compressor shuts off you should immediately hear a short hissing sound indicating that the valve is working.

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The compressor very seldom kicks out the breaker on initial start up, usually it runs till it is within 5 or 10 psi of kicking off and it blows the breaker. I replaced the breaker today with a new one but that didnt seem to help. The breaker it is hooked to only serves one outlet (used to serve 2 but the other has been eliminated). Is it possible to make that a 30 amp ciruit? I have access to all the wire going to that outlet. Either that or I might have to try the tranny fluid trick.

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mfishinguy is right. Need more details. It sounds like the current draw is within the circuit specs until the pressure in the tank gets up to a certain level. Could be that your tank pressure is set higher than spec or the supply circuit may be inadequate.

Whatever you do, DO NOT replace the 20A circuit breaker with a 30A! If it is wired for 20A you could risk an electrical fire by doing so.

Bob

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Quote:
What gauge wire is that circuit on?

Be careful with this question. Be sure to check the entire circuit. Too often I've heard of electricians wiring a 15A circuit using some 12ga. Not illegal but foolish if you as me. It fools less competent home owners and even seasoned electricians later when they mistakenly assume the entire circuit is wired with 12ga and choose to upsize the OCPD to 20A.

A competent electrician would never assume anything.

Bob

Edit: Correct me if I'm wrong but is it still allowed to use 14ga. pigtails to supply 15A receptacles on a 20A branch circuit?

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I belive it is 12ga but Im not 100% sure. There is literaly 2' of wire between the outlet and fuse box. The compessor shuts off at 135psi just as it should. I drained the oil and replaced with ATF today, seemed to be better but time will tell.

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Well I replaced the oil with ATF and it is deffinetly better but it still trips the breaker once in a while. Is is possible to make this into a 30amp circuit? What would be involve in doing this right? Like I said I have access to the entire ciruit.

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"I belive it is 12ga but Im not 100% sure."

If theres only 2' of wire between the fuse box and receptacle why not take a look and tell us what it is?

If its 14 gauge on a 20 amp breaker thats not safe. The idea behind the breaker size is to protect the wire. It could also be the root of your problem.

If you run 10 copper AWG off the breaker or fuse panel and use a 30 amp breaker. That wire is protected by an appropriate size breaker. What gauge wire is on the compressor's cord? If its not 10 then you you can't use a 30 amp breaker.

The 20 amp breaker on 12 copper AWG should be sufficient for your compressor. Your compressor is tripping a 20 amp breaker when getting up to 135 psi. Why is that? Thats what you should be figuring out. It could be as simple as a cheap 25 cent receptacle or it could be the motor is getting hot or just wore out. Right now the 20 amp breaker intended to protect 12 gauge wire might be protecting the motor. Protecting the device isn't the breakers intention, as said it protects the wire. Putting the compressor with a suspect motor on a 30 amp circuit could toast the motor. If your going to treat the symptom then turning the cut off pressure down would be way better then a 30 amp breaker.

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If your going to treat the symptom then turning the cut off pressure down would be way better then a 30 amp breaker.

Or a guy could put a bigger pulley on the compressor (or smaller on the motor) to lessen the load on the motor. It may fill very slightly slower but with less load on the motor with the same output PSI.

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I have the same size compressor, I believe. When my house was built, the electrican mounted two GFI outlet boxes, right near the breaker box in the garage. One towards the top of the breaker panel, the other near the bottom. The builders used them when building the house.

During the winter, my compressor will trip the lower 2-outlet box, all the time, during cold weather. So, last year, for giggles, I tried plugging it into the upper GFI outlet box. It has never tripped a breaker during winter yet.

Maybe a weak breaker? I don't know.

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I have the same size compressor, I believe. When my house was built, the electrican mounted two GFI outlet boxes, right near the breaker box in the garage. One towards the top of the breaker panel, the other near the bottom. The builders used them when building the house.

During the winter, my compressor will trip the lower 2-outlet box, all the time, during cold weather. So, last year, for giggles, I tried plugging it into the upper GFI outlet box. It has never tripped a breaker during winter yet.

Maybe a weak breaker? I don't know.

Heat rises. Maybe the top receptacle is warmer. smirk

Bob

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