Can’t figure out why breaker tripped

Do regulare non GFCI breakers trip for reasons other than overcurrent? I was doing some framing work & the only thing I was using was my compressor (I had some lights & a table saw plugged in, but they weren’t on).
Anyway, it’s a 20A circuit & the compressor pulls 10A. It’s never tripped before & after I reset it, everything was fine. I felt the breaker, the outlets & extension cords & nothing felt warm. Could this indicate a problem with my compressor? It tripped when it first started up, but again, I’ve never had this issue before.
Replies
How much extension cord are you on? Put a compressor on an extension and try to start it with a nearly-full tank and it'll stall and blow the breaker.
happy?
It's on a 50 ft cord...
Hi Soultrain. Danh H. gave you the right info.
Extension cords are VERY PROBLEMATIC for compressors...and 50 ft cord is waay too long!
Keep your compressor plugged in close to the outlet, and let your air hoses extend your reach...putting on an additional 50 ft of air hose will not affect your compressor's ability to function properly...but long extension cords will, over time, cause extreme harm to your compressor.
Davo
Thanks guys. Hopefully I haven't damaged the compressor. I've been running on the extension since I got it.
I'll spring for another 50 ft. hose instead...
If you must use an extension, use nothing smaller than an #12.
If ignorance is bliss why aren't more people
happy?
It is a #12 - I never use anything less - for anything :)
Regardless, I'll get some extra hose & plug it in directly.
Yeah, even with #12, 50 feet is a long run. 25 feet would probably be OK.
If ignorance is bliss why aren't more people
happy?
Compressors take up to 3x the current at startup. So I expect the problem will happen without the extension cord as well.
Let us know how it works out.
A 20A breaker should be able to handle the brief startup overload. It's when the startup drags on due to voltage drop that you get the pop.
If ignorance is bliss why aren't more people
happy?
"Do regulare non GFCI breakers trip for reasons other than overcurrent?"
Since no one else answered this question, I will. The answer is yes, an no. Modern circuit breakers will trip by one of two methods, one is pure overcurrent in which an induction magnetic trip will open the breaker due to a very high current (ie. in the event of a "short"), the other method is thermal overload in which a bimetallic element will heat up and open the circuit. The thermal overload is due to continuous high current that is caused by a high load near or above the breaker amp rating.
The thermal overload also can weaken a breaker, causing it to trip at much lower than rated amperage. Maybe time to get a new breaker.
This is a new circuit, so I doubt the breaker is worn out...
It's not unheard of for a breaker to be bad out of the box (or to be returned goods, for that matter). But this still sounds like some sort of "hard start" situation (starting under load).Some compressors are rigged to unload the compressor during starting (eg, holding open the compressor intake valves). Others just rely on the motor to do it's job.It might be a good idea to plug the compressor into a different circuit, start it up, then slowly valve off air until it restarts. Could be a bad connection on that specific circuit, or something similar.
Also, be sure you haven't adjusted the low pressure setting on the pressure switch upward above spec -- the higher the low-pressure (turn on) setting, the harder the start will be.
If ignorance is bliss why aren't more people
happy?
Edited 4/5/2006 4:01 pm by DanH
Maybe there's a ground on the motor side of the pressure switch. I'd unplug the compressor and measure the continuity from the hot leg to ground. If it is low then look for a frayed wire downstream of the pressure switch.
I had the same problem with breakers tripping with my compressor. I had a twenty amp circuit and a 15 amp compressor. My compressor had a notice on it to use a type D time delay breaker. I called my local electric supply and they didn't know what i was talking about. I went through 3 or 4 brand new breakers before I finally installed one that would not trip constantly when my compressor goes on. It hasn't tripped in months.
Yeah, drill a hole in the breaker and squirt in a little epoxy. That'll solve the problem. :-)
If ignorance is bliss why aren't more people
happy?
UPDATE:
I bought an extra length of hose & plugged the compressor directly into the outlet, but the breaker still tripped (same issue - compressor filled the first time, but when it went to re-fill after nailing for a bit, the breaker tripped).
I called Porter-Cable & described the problem & was told that the check valve likely needed to be cleaned or replaced. I was also told that if the check valve is bad, since it's only 9 months old, replacement would be free.
Anyway, when I get home tonight, I'll check it out & see if that takes care of the problem.
I used to have an air compressor that would blow the breaker on restarts on every outlet in my house - except for the one that I installed right under my outdoor breaker box, which was on the opposite side of the pole from the meter. If I used one of my really heavy duty extension cords on that outlet, it still worked. But, any outlet that was there when I moved in was a no-go.
Keep in mind that most 15A circuits (and an appalling number of those on 20A breakers) are #14 wire. Add backstabbed connections and you have a pretty small hose for all the juice that flows during startup.
If ignorance is bliss why aren't more people
happy?
I knew quite well what the problem was - cheapest answer they could put in that met code. What I put in worked just fine.
I was just pointing out that blowing a breaker with an air compressor on a restart isn't at all uncommon - and sometimes the fix is to add an outlet that is wired right.
Yeah, my post was more for the benefit of the OP.
If ignorance is bliss why aren't more people
happy?
This is a 20A circuit w/ #12 copper. I checked all the connections on the circuit & they are tight, so unless the breaker is bad, my money is on the compressor being the fault. I don't have any issues when I run my table saw on that circuit...
I didn't get a chance to examine the check valve yet, I hope to get to that tonight.
Edited 4/6/2006 9:44 am ET by Soultrain
Good news everyone!!
I checked the compressor on another 20A circuit (on which it had worked before & that breaker tripped as well, so I knew it was the compressor).
I had called Porter-Cable before & they said it sounded like an issue with the check valve, but I wanted to rule out the breaker before I dug in.
Anyway, after ruling out the breaker, removed the check valve (owners manual described how to do it & said it would not void the warranty). Low & behold, there was a tiny piece of debris lodged in the valve keeping it open. I ran water through it until it came out.
Once everything was put back together, it worked like a champ.
Ok, here's my latest thought on this:
You say that it trips the breaker after it's first fill.
Most pressure switches have a 'bleed down' valve that releases the pressure between the pump and pressure switch when the switch cycles off. You'll hear a distinct hiss when the pressure switch trips, the valve opens, and the motor stops. The pressure release is so the motor doesn't have to push against ~100 psi when starting the next time.
If the pressure release valve isn't working, this would make starting a lot harder, thereby requiring far more current, possibly enough to trip a breaker.
Do you hear a hiss when the switch cycles?
Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
Sounds like you got it Scott.
If the compressor doesn't unload it will go over current, long enough on start up, for the breaker to trip. Most electric motors will have a start current as much as 2 to 3.5 times the FLRA rating. Sometimes this is listed as Locked Rotor Amps. Breakers are designed with a time delay in them to allow the passage of the FLRA or LRA. When that time has elapsed, they trip to protect the circuit wiring.
Sounds like PC will replace the compressor b/c it is still under warranty.
Dave