Actually wanted to verify your theory on the loop voltage drop on AC. Called our electrical guru here at work (it's what he does for a living, AC/DC power, generators, etc.) and he advised me that a general rule of thumb is that if you're running the proper size wire with the proper size breaker for a given application (i.e. 12 AWG/20A breaker, ~13A draw on the compressor IIRC) then the general rule of thumb is the approximate distance of the voltage of the supply voltage 'in one direction'.

IOW, my 20A breaker at 120V on 12AWG wire I should be good for approximately 120' one way, or 240' loop without incurring any loop voltage drop. I'm not even close to that so shouldn't be seeing any problem due to the length of the circuit from the service panel to the outlet I'm plugged into.

For some reason it was acting like a 'hard start' when the breaker would blow and being that this was an oilless unit I could see that happening, it was intermittent and usually would occur after the compressor had sat for a few days/weeks without use, never happened after the initial start-up or while in use.

HTH

zman

 

zman, I agree in theory. The problem comes from the motor start inrush current and I think those Craftsman compressors might be a little understated as a selling point. I do know that when my compressor starts in my garage, I can see the lights dim slightly in my house and my garage is on a different service panel (split drop). Compressors seem to take a lot of juice for the rating and I ran the next size larger wire to mine just to be safe. Nothing beats peace of mind.
Just my 2¢
Greg

 

Guys, Just wanted to add my 2 cents worth.

Breakers can deteriorate under heavy loads, it weakens the trip spring. The compressor on start-up can draw about 22-25 amps and settles at 15-17. If the tank was nearly full of air, then the motor has to work harder to get up to speed. I didn’t hear anyone say that their problems were when the tank was full or empty. Boss_358, was it possible to run this on 220V? If so, then I would think you would have done so. Also, were you using the screw contacts or the slip in kind? Screw contacts make much better connections.

220V circuits draw 1/4 the amperage of 110V circuits. The voltage drop occurs because of the amount of current along with the length. Zman’s number’s are basically right, a 13 amp line can run about 100 feet, but take that to 18-20 amps (considering motor start-up), then its more like 50 feet. The rule is only a 5 percent voltage drop, or 114V on a 120 line. A handy little calculator is at:
http://www.stanselectric.com/vdrop.html

At two feet away, Boss shouldn’t have this problem. Going to 10 gauge for this distance shouldn’t make a difference. Check the connections in the box to include the main common (white bus bar) as well as the connection to the breaker.

Boss_358, did you solve this yet?

Friar

 

did you check if you got a capacitor start on the comp?
would make for a big load on start up if no good

 

I've read about 12 of the other replies and havn't heard this mentioned yet so I'll add my two cents. CEMF (counter electromotive force) is a extremely high current that occures over an extremely short period of time. This occures when AC motors start up or have large amounts of torque applied to them. At the instant the switch is closed, you essentially have zero voltage across the motor and infinate current. The split second after the switch is closed the motor actually starts to act as a dynamo, generating its own electricity back onto the power line countering the AC coming in. Eventually this will reach a state of very low current and a voltage equal to the line voltage.

If you have a situation where the crckt brkr trips only on occasion it could be because of the addition of other power consuming devices on the same circuit. Make sure all other devices on that circuit are turned off and this should solve the intermittent problem.

The 20A rated wire should be OK. But the breaker can definately get 'weaker' with every trip and can even be damaged to the point of tripping at a lower current than rated, say 10A for example. Changing the breaker will definately help.

If the compressor calls for a 15A breaker and is tripping a 20A breaker consistantly, something is causing an extended high torque situation at the compressor motor. Check bearings and moving parts to make sure everything is clean and properly lubed. Even if things seem to be moving alright when the motor is running, static friction can be exponentially higher due to dirt, oxides or improper lubrication.

If the compressor is rather old, you may want to have the start up capacitors replaced. These capacitors help minimize CEMF upon start up.

Remember, any mechanical device needs cleaning and lubing on a regular basis regardless of the amount or severity of usage.

Hope I helped at least a little.

 

Ok guys, I just finished up and this is what I did with my results. I replaced the breaker and the wiring going from the breaker panel to the outlet. I stretched the wiring out to about 10 feet and relocated the outlet to my garage attic while I was at it. This way I won't have to listen to it run anymore. Oil free compressors are way too loud! I even bought some new wire cutters and needle nose pliers to make sure none of my connections got damaged. I noticed my old pliers used to nick the wires a little. I just finished up and everything seems to be working normal. There is the load that occurs right upon start up that always dims the lights for just a second but this has always been normal. I think the problem was the breaker. There was never a problem with this outlet until I accidentally arced the wires. Thanks everybody for your help and comments.