Compressor tripping the circuit breaker

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Forum topic by BentheViking posted 08-11-2012 03:05 AM 6764 views 0 times favorited 23 replies Add to Favorites Watch
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1782 posts in 3487 days

08-11-2012 03:05 AM

Topic tags/keywords: air compressor electrical

I recently inherited a compressor from my father in law. The thing hasn’t seen much use the last few years and my brother in law didn’t even think it really worked. So tonight I got the thing out of my truck and plugged it in in the garage. Flipped the switch and low and behold it started right up and the tank started filling (albiet a minor leak in one of the hose fittings). After a minute or so the lights in the garage flickered and then the garage was dark and the compressor was off.

So I drain the thing and go flip the circuit breaker down in the basement. A little while later I was bored and figured I’d try it again and same thing happened. Both times the tank was about half pressurized (60-80 PSI).

So here is what I have—compressor is a Craftsman from about the mid-90s. 3HP 20G. Model #MO-3640.

Circuit is a 15A that really doesn’t have much on it (I think) some lights and outlets and the garage door openers.

I guess I’m wondering if anyone has that compressor or a similar one (love some more info on it) or just electrical info in general as to why it works fine until it has to get into a higher pressure range and then it seems to draw too much power. thanks in advance.

-- It's made of wood. Real sturdy.--Chubbs Peterson

23 replies so far

View Sawkerf's profile


1730 posts in 3992 days

#1 posted 08-11-2012 03:08 AM

If you have the owners manual check the starting and run current requirements. It should probably be on a 20A circuit. Actually, all receptacles should be on 20A circuits.

-- Adversity doesn't build reveals it.

View BentheViking's profile


1782 posts in 3487 days

#2 posted 08-11-2012 03:11 AM

I don’t have a manual and have yet to come up with one online. The receptacle is a 15A. my next test would be to try a 20A

-- It's made of wood. Real sturdy.--Chubbs Peterson

View johnstoneb's profile


3163 posts in 3096 days

#3 posted 08-11-2012 03:13 AM

I think you have to much load for a 15A circuit. It takes a little time for the current draw to heat the CB to the point where it trips. The label on the motor shuld tell you somewhere what amperage the motor draws. I used to have a single 15A circuit in my garage and when I ran the table saw (1.5 HP) and lights it would trip the breaker after just a short time.


-- Bruce, Boise, ID

View fussy's profile


980 posts in 3974 days

#4 posted 08-11-2012 03:30 AM


That thing needs to be on a 20 amp circuit by itself. That means 20 amp breaker, 20 amp outlet, and
12-2/with ground wire in between. Also, change out the oil using compressor oil, and check the air filter. Most likely a foam pad on top of the cylinders—probably gone so replace it. Also, take out the big plug in the tank (you’ll need an impact wrench) and visually inspect the inside of the tank to be sure it’s not rusted.
Check the pressure gauge on the tank to make sure it works and make sure the pressure limit switch shuts it off at around 120 psi or less. Replace it if in doubt. It and the gauge, oil and filter are available ant any good hardware store.

That’s a nice compressor. Enjoy.


-- Steve in KY. 44 years so far with my lovely bride. Think I'll keep her.

View Grandpa's profile


3263 posts in 3599 days

#5 posted 08-11-2012 03:49 AM

DITTO on the 20 amp circuit. Yes they do need it.

View Bluepine38's profile


3387 posts in 4009 days

#6 posted 08-11-2012 03:09 PM

Check the amp rating on that motor. My Craftsman electric 1 HP motors are rated at 11.7 amp. That 3HP
might need to have a special 10 guage wire run from a 30 amp breaker, but I am sure it will need at least a
20 amp circuit to operate.

-- As ever, Gus-the 80 yr young apprentice carpenter

View Wdwerker's profile


333 posts in 3157 days

#7 posted 08-11-2012 04:16 PM

The start up and first half of filling the tank is easy on the motor. It is tripping the breaker when the load exceeds the amperage of the breaker.

-- Fine Custom Woodwork since 1978

View BentheViking's profile


1782 posts in 3487 days

#8 posted 08-12-2012 02:49 AM

So I looked at the compressor. Its actual model number is 919.176830. According to the tag on the unit it does draw 15A so it seems as if as soon as it starts getting up in load and I also have a light on boom. Some day this week I’m going to run a thick gauge ext cord from a 20A circuit and see how that works out. Just glad it doesn’t seem to actually be anything wrong with the unit. Now I just have to figure out how to change the oil and the filter and I’ll be in business

-- It's made of wood. Real sturdy.--Chubbs Peterson

View MedicKen's profile


1615 posts in 4386 days

#9 posted 08-12-2012 02:59 AM

Are you sure the compressor is not the oilless design? I just sold one that had the exact same symptom, and that was on a 20A circuit. It may be that the contacts are getting dirty and need a little cleaning. I found that was the case with mine. I took a very small, fine point file and carefully cleaned them up. After that it would run fine but still occassionally pop the breaker. You might google the model number and see what complaints are the norm for that model.

-- My job is to give my kids things to discuss with their [email protected]

View BentheViking's profile


1782 posts in 3487 days

#10 posted 08-12-2012 03:03 AM

It absolutely is a oiled compressor. I found the manual online and there is a section in there about how to change the oil and also was able to use the manual to point out where the oil fill and drains were and sure enough there they were on the compressor.

Sorry I’m not so good with the more mechanical side of things, but what do you mean the contacts?

-- It's made of wood. Real sturdy.--Chubbs Peterson

View BentheViking's profile


1782 posts in 3487 days

#11 posted 08-13-2012 02:23 AM

If I can’t easily hook it up to a regular outlet I could always hook it up to this generator that I have. Or would that not work. I figure it can power the house so it should be no problem doing a compressor for a little bit

-- It's made of wood. Real sturdy.--Chubbs Peterson

View Danpaddles's profile


588 posts in 3235 days

#12 posted 08-13-2012 02:38 AM

Not sure the extension cord is the way to go. There will be a voltage drop, even with a large cord. That also introduces an extra plug- which could add bottlenecks.

Can you instead move the compressor to the 20 amp outlet? Or maybe just drop in a larger circuit? 10 gauge wire, properly fastened to the logs and terminals, will have less voltage drop than a cord.

FWIW- my 11 amp compressor pops my 20 amp circuit every now and then (as does my 13 inch planer).

-- Dan V. in Indy

View jim C's profile

jim C

1472 posts in 4022 days

#13 posted 08-13-2012 02:51 AM

Do it the easy way. Stick a penny behind the fuse.
If you have circuit breakers, pull the breaker, cut a copper water line to fit, and replace the breaker.
I’ve never had a power failure after following these rules.
Why be electrically, politically correct in these instances. We can’t waste time with rules. Go for it.
I’m running a 3 H.P. shaper on a 15 amp line using these simple steps.

View Grandpa's profile


3263 posts in 3599 days

#14 posted 08-13-2012 03:28 AM

Jim C, is that your house I see smoking over there…..or the remains of your house? Those tricks would carry a bunch of current.
I have a friend that owned a compressor like described above. It would trip the breaker so he ran it on 220V and got by with that. Compressors can be troublesome. Give them plenty of current and they do okay.

View TopamaxSurvivor's profile


19858 posts in 4599 days

#15 posted 08-13-2012 04:47 AM

Either it is smaller than 3 hp or it draws more than 15 amps full load. A 3 hp draws in the neighborhood of 30 amps on 120 volts.

What brand is your panel with the breaker in it?

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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