craftsman air compressor tripping breaker - solution


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Old 01-02-07, 06:21 AM
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craftsman air compressor tripping breaker - solution

A couple months back I purchased a used craftsman air compressor. I knew it had issues when I purchased it and fixed them. I went to use it about a week ago and it started ok with no air in it, however, when it went to replenesh the air and pressure, it was now tripping the breaker. After re-examining all the usual suspects, I realized it was the motor. I removed the motor and brought it down to our local electric motor repair shop here in South Jersey. Here is what they found/did; 1. disassembled motor and inspected 2. found open connection 3. repaired shorted coil 4. replaced start capacitor 5. re-assembled and tested. They charged me 74.80 which I thought was reasonable. I brought the motor home and re-assembled the compressor. it worked great. There appeared to be a huge increase in power and torque. I have seen many posts on this forum about this problem, however, I didnt remember anyone submitting a post on how the problem was finally resolved so I figured I would share these findings.
 
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Old 01-02-07, 06:55 AM
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Wow, thanks for the info/update

So it looks like a shorted coil and/or bum start capacitor?

Interesting
I've been using a P-C compressor that has also been tripping breakers left and right
I assumed it was because most of the old converted cottages around here have sub-par electrical
...and it's true, but I've tripped some pretty newer ones too

It never trips on start-up, only when it kicks in again

The P-C is not new, but had hardly (if it all) been used before I started using it last year
Maybe I should remove the motor and have it looked at
Thanks!

(I've been using a generator to avoid the problem
It also helps because many of the homeowners are not here year-round and/or weekdays, and often there's little/no electrical outside
I can have a few saws and sanders going, so I've been playing it safe with the genny
So it works out OK, but if I didn't have to start up the genny even for the quick nail jobs it could help)
 
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Old 01-02-07, 07:03 AM
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Slickshift

What size generator do you use? I have a 5000 watt generator that runs my airless great [and any other tool] but it struggles with my 1hp craftsman compressor.
 
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Old 01-02-07, 07:54 AM
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Same size as yours Mark

The compressor (I think th P-C is a 1.5 hp) does give it a bit of a hesitation when it kicks in
If it kicks in while the 15Amp saw is running, well...it'll hiccup pretty good

I suspect if I was running few things, like maybe leaving a 15Amp saw running and starting up a 10 or 12 amp tool when the compressor kicks in, the genny might just die
I try and avoid being in those situations
Mostly it's just me (not a crew) so it's not really an issue
 
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Old 01-11-07, 04:21 PM
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I suspect the problem is one of insufficient voltage/current. You probably have a 1-lunger and a direct-drive compressor.

The power required to start the motor spinning with no back-pressure against the piston (i.e. an empty tank) is much less than that required when a partially filled tank is applying pressure against the piston.

I measured the voltage at the compressor's plug when starting on an empty tank, and had about 105 VAC (115 VAC when the motor was off). Then I let the tank fill to about 80 psi, turned the motor off, and measured the input voltage when I turned the motor back on.

85 VAC. Not enough to spin the motor fast enough to start it. The rotor stopped ( aka stalled rotor) and after 5 seconds, the breaker tripped.

Very common problem with 115 VAC compressors. About the only way to defeat it is to run a line from the breaker box to the area where the compressor will be used. Assuming a so-called "2-HP" motor, which is really a 115 VAC, 15-amp motor, you'll need #12 wire from a 20-amp breaker and a run not over 50 feet. (May be 75, can't remember). Best way is to run #10 wire from a 30-amp breaker (could also use a 20-amp breaker). The larger the wire, the less the voltage drop.

Ideally, get a 220 VAC unit. Draws half the current and won't trip the breakers.
 
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Old 01-11-07, 04:33 PM
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Thats some interesting stuff. I just signed up here because my craftsman is tripping the breaker its on, also its brand new. How much does it cost to have a dedicated line ran normally, any idea? My main problem is my breaker box is in the basement on the opposite side of my house from the garage and the basement only goes about half way across the foundation not even close to my garage. I do have a friend who is an electrician but can never get a hold of him to come look at the situation. I dont understand how a compressor like this sells so much over years and the breaker trip seems to be a big problem. And right now another compressor is out of the question plus a 220 line would still have to be ran. Would another line have to ran outside around the house to the garage to the new outlet or is there a trick to run it within the walls? Sorry for all the questions!!!

jl66redcpe: How old was the compressor you purchased?
 

Last edited by DIYaddict; 01-11-07 at 04:40 PM. Reason: Removed quote
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Old 01-11-07, 04:45 PM
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Is there a crawl space you can run the wire thru?
 
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Old 01-11-07, 05:30 PM
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unfortunately no crawl space
 
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Old 01-11-07, 07:33 PM
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Better to feel funny (although not warranted here!) for asking questions than being sorry for not asking them!!

I don't know how much electricians charge in your area. I have a similar problem but with a table saw and dust collector I use in my garage. The plug for the two of them is about 80 feet from the breaker box, so I have to install my own run. The work is fun for me ('cause I don't HAVE to do it but the material is expensive.

After a lot of help from the Electrical part of this forum, I'll be running PVC conduit from the breaker box at the rear of the house, around a corner and up 25 feet to the entry point inside the garage, then about 15 to 20 feet inside the garage. Conduit and fittings not that expensive, but 100 feet of #10 wire is. Especially 'cause I'll run 4 wires.

Back to the circuit blowing part of the thread - fortunately my compressor gets enough ummpf from a 15-amp receptacle in the garage where I use it for automotive stuff. It also will reliably restart at the opposite corner of the house where I use it to blow out my sprinkler lines each Fall. But anywhere else, I have to try to keep the thing running all the time or else the rotor locks and 5 seconds later a breaker trips.
 
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Old 01-11-07, 07:53 PM
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yeah, i finally talked to my buddy and he's going to come check it out. He said worse thing we will have to do the PVC run and all that fun stuff but he wants to look at a few other things first. He said my house is wired wrong technically for todays standards because apparently my garage outlet, all bathrooms and outside outlet are all on the same breaker. Main reason I bought this compressor was because it is suppose to fine off a 15amp circuit. But since we realized about the other outlets that go off the same breaker I guess I def need a stand alone one just for the compressor.
 
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Old 01-13-07, 05:21 AM
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Originally Posted by fox_forma View Post

jl66redcpe: How old was the compressor you purchased?
Sorry for the late response, I was out of town.

I believe the compressor is from 1999 however it had very little use judging by condition. I bought this used a couple months ago. I was aware at the time it had issues. It served as a nice project for me.
 
 

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