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Old 02-20-2012, 04:17 AM   #16
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Well pump trips breaker at start, but then starts when breaker reset


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Originally Posted by mpoulton View Post
#14 wire on a 40A breaker may not be your preferred installation, but it is code compliant and there's nothing wrong with it in this specific circumstance. He says the run is only about 30 feet, so voltage drop is unlikely to be an issue - especially since he actually has #12 installed. Using a 30 or 40A breaker is perfectly fine for this application and may fix his problem. However, it seems likely that either the motor or the breaker has a problem because an upsized breaker really shouldn't be necessary to start this motor.
"[quote=mpoulton;858013]#14 wire on a 40A breaker may not be your preferred installation, but it is code compliant and there's nothing wrong with it in this specific circumstance."

True to code, but hard to take at face value. If you look at the big picture, with the thermo protection on the motor it makes sense. But I still ran #10 on a 30amp breaker for my new compressor. But then again the wire is free too me.


Writerís information is for discussion purpose only and should be confirmed by an independent source.

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Old 02-20-2012, 05:38 AM   #17
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Well pump trips breaker at start, but then starts when breaker reset


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Many thanks to all those who responded.

With regards to the start capacitor, I replaced it, but then had the original one tested at Grainger and it was found to be good. There was no evidence of leakage, either. I am fairly confident that is not the problem.

With regards to the centrifugal switch, I cleaned the contacts and also checked the resistance across the switch at rest and it was a small fraction of an ohm. Thought it may have been sticking, so I cleaned and lubricated the mechanism. I am now fairly certain that is not the problem.

With regards to the bearings, there is resistance to turning, but it does not feel excessive. Since the motor is still assembled to the pump, I would expect there to be some amount of drag.

With regards to the breaker, it is a Homeline by Square D. I believe that I have 12 AWG conductors which I think are rated at 20A for 600V and 100 feet of conductor. Again not positive of conductor size and rating. The pump is on the opposite side of my garage from the breaker panel. So I have much less than 100 feet, probably closer to 30 feet. I will measure the cable tomorrow to be sure. Home Depot has a 30A breaker for my panel, which I may try.

I am suspicious of the start windings, but do not have a megger to test. I am not sure my multimeter can handle the current.

Again, thanks for all of the advice. Need to avoid needlessly changing out a motor or pump if I can fix what I have. Every penny counts.
Thanks for providing so much good information in your original post as it helps with troubleshooting and gives people an idea of your knowledge. From your description of the motor turning slowly when the breaker trips I wouldnít replace your breaker with a 30 amp at this point because Iím almost certain there is something wrong with your start circuit. I would still focus on your start switch because itís mechanical and a bit old. The contacts can become intermittent once the plating is burned off and the mechanism gets sloppy with age.
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Old 02-20-2012, 05:59 AM   #18
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Well pump trips breaker at start, but then starts when breaker reset


Is reconfiguring the motor for 240V an option? Often these motors have jumper straps to permit changing voltage for motor. If you can do this you'll halve the motor current. As a result your voltage drop (R*I) in lines will be less. While it may be fine to use #14 for the steady state running of the motor you have to consider the voltage drop the motor will see upon startup due to IR drops. That may be part of your problem.

So I would try going to 240V if possible and failing that you might want to consider beefier wires to handle the startup current.

I have a 3HP compresor in my garage that came 120V and often popped the breaker in cold weather. I swapped it to 240V and it starts up quicker and has never tripped a breaker since.
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Old 02-20-2012, 06:43 AM   #19
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Well pump trips breaker at start, but then starts when breaker reset


[quote=Hardway;858035]"
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Originally Posted by mpoulton View Post
True to code, but hard to take at face value. If you look at the big picture, with the thermo protection on the motor it makes sense. But I still ran #10 on a 30amp breaker for my new compressor. But then again the wire is free too me..
It's not commonly done in residential work. When it is, it's usually only for AC compressors that specify a wire size and OCPD right on the nameplate so nobody has to do their own calcs. In industrial facilities, motor circuits are pretty much always sized according to Article 430. They also tend to incorporate more complex systems like starters (delta-wye) or VFDs that also influence the conductor and breaker sizing.
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Old 02-20-2012, 08:23 AM   #20
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Well pump trips breaker at start, but then starts when breaker reset


its none of that.......your blew your motor widings......change the motor......leave the wiring alone....its drawing alot of amps to get going and trips thats all.........change the motor and the seal
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Old 02-20-2012, 09:42 AM   #21
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Well pump trips breaker at start, but then starts when breaker reset


Again, many thanks to all for the input.

Confirmed wiring is 12 gauge. Length may be more than 30 ft but no more than 45 ft.

At rest, there is less than 1/2 ohm resistance across the start switch.

Will see if I can borrow an ammeter from work tomorrow to check current draw.

Will also see if there is a megger I can borrow.

While rechecking the start switch this morning, using my multimeter, I checked the resistance of the power leads to ground: both read infinite resistance. Then I checked the resistance of the shaft to ground: read 34.4 ohms. I do not know what it should be, but suspect that is low.

I cannot use the existing wire in the wall to reconfigure the supply for 230V. There is not enough conductor in the breaker panel to rig a double breaker. The pump does have a selector switch to change over. Since I have run on 115V all of these years, I don't think that should be necessary.

Something is broken. Unfortunately, I cannot rationalize how the breaker will trip when the pump first tries to start and then will start just fine when the breaker is reset. Stiction in the motor bearings would be my only smoking gun, but I have turned the motor after it has set for awhile and it really does not take much torque for it to turn.

As a temporary measure, I have installed a 30A breaker. I will monitor it through the day to see how things go. If it trips, then I think the correct course of action is to replace the motor.

Again, I am very grateful for all of the help.

God bless,
Dave
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Old 02-20-2012, 04:21 PM   #22
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Well pump trips breaker at start, but then starts when breaker reset


An update for those interested.

Have had no issues with the 30A breaker installed.

Borrowed a clamp on ammeter from a neighbor. Starting current appeared to be approximately 30A, running current 8A. The needle on the ammeter peaked and then dropped off without hesitation, so it was hard getting a definite reading.

I was looking at replacement pumps and found detailed technical data on the Sta-rite web site. For their 1 HP pump, they recommended a 20A breaker and 12 AWG conductor/cable.

I am not totally comfortable leaving the 30A breaker in place.

On one blog, I found a discussion of the quality of the line of breakers that are installed in my power panel. The discussion was not favorable, though I have not had any issues up till now. The genesis of that thread was the Homeline breaker tripping; the service was a grinder. Without trying to regurgitate all of the discussion, the issue appeared to be insufficient delay in the breaker for the motor in the circuit.

Here is a theory I offer for anyone to comment on: the 20A breaker that was installed eventually weakened [for lack of a better term in my mechanical vernacular] and then started to trip. I replaced it with another 20A breaker that was not as 'strong' and it tripped immediately [as I have previously posted].

Back to my reservation with the 30A breaker: what if I installed a 20A fuse block in line? The intent would be to allow the spike at start, yet still have the protection at 20A offered by the fuse. Not sure this is worth the effort or that the fuse will permit the rapid spike. I will do a little more research on fuses.

I really appreciate all the input I have received and y'all's willingness to help.

God bless,
Dave
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Old 02-20-2012, 04:25 PM   #23
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Well pump trips breaker at start, but then starts when breaker reset


Rewire for 240 and life will be good!!!
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Old 02-20-2012, 04:32 PM   #24
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Well pump trips breaker at start, but then starts when breaker reset


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Rewire for 240 and life will be good!!!
Think about it. If ir drop of motor at startup is say 20vac or 17% of voltage. Now switch to 240 and current is half or 10 vac drop but now on 240vac or 4%

17 to 4% just to move a neutral wire to opposite phase and swap a jumper under a cover of motor. Easypeasy
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Old 02-20-2012, 05:33 PM   #25
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Well pump trips breaker at start, but then starts when breaker reset


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Back to my reservation with the 30A breaker: what if I installed a 20A fuse block in line? The intent would be to allow the spike at start, yet still have the protection at 20A offered by the fuse. Not sure this is worth the effort or that the fuse will permit the rapid spike. I will do a little more research on fuses.
There is absolutely no reason to do that. It is not required by code and provides no real safety improvement. The thermal protection in the motor is completely adequate for overload protection of the #12 wire, and the circuit breaker is perfectly adequate for short circuit protection. If you really wanted to, you could do it and use a time-delay fuse. But there's no reason to.

What you probably should do is rewire it for 240V. You can use wire nuts in the panel to extend the existing conductors if they aren't long enough. If you don't have any spare slots and the panel is listed for tandem breakers (if it's 30-slot or smaller, it probably is), you can install a tandem breaker on a different circuit to free up a space. You will need to use a 20A 2P breaker not 30A - can't go larger on 240V with that motor and wire.
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Old 02-20-2012, 08:48 PM   #26
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Well pump trips breaker at start, but then starts when breaker reset


Received advice from electrician at Home Depot to not install a fuse. Glad to hear that others agree with him.

Would have switched to 230V today, but finding the neutral wire is more than I want to do right now. It is buried in all of the other neutral wires and behind some of the major power cables. I am going to have to do that when the family is not home and I can kill power to the house.

Thanks again to all who have offered advice.

God bless,
Dave
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Old 02-21-2012, 12:27 AM   #27
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Well pump trips breaker at start, but then starts when breaker reset


In my experience, Square D breakers tent to trip on the lower end of the scale.

I don't know if they make a HM (High Magnetic) version of the HOM 20 amp, but they certainly do in the QO line.

According to the Square D trip curves, a 10 amp (yes, they make them) will hold more instantaneous current than a standard 15 or 20.

I'm comfortable with the idea of the old breaker getting weak as time went on, ultimately tripping when there is no fault, and the new breaker being too weak to handle the start current of the motor.

I'd also be completely comfortable with a 30 and #12 wire for this motor.

But, as others have said, if possible, run it on 240.

Rob

P.S. The Square D two pole breakers have a much higher instantaneous setting that the single pole ones. About the same as the HM version of the single pole.
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Old 02-21-2012, 01:29 AM   #28
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Well pump trips breaker at start, but then starts when breaker reset


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In my experience, Square D breakers tent to trip on the lower end of the scale.
...
I don't know if they make a HM (High Magnetic) version of the HOM 20 amp, but they certainly do in the QO line.
...
P.S. The Square D two pole breakers have a much higher instantaneous setting that the single pole ones. About the same as the HM version of the single pole.
Very interesting! I never would have guessed that there's so much variation in trip curves between standard breakers with the same nominal rating. Thanks for the info.
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Old 02-24-2012, 09:55 PM   #29
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Well pump trips breaker at start, but then starts when breaker reset


For those of you who might still be following this thread, I did a little more research, first at the hardware store and then on the internet.

I found a GE breaker that fit my power panel; then looked online for info. I found the attached time trip curve for a 20A breaker. I saw from the curve that it should handle the high motor start up current. I installed the breaker today and it has worked flawlessly. Nothing against the Square D breaker, it just isn't appropriate for the motor application.

Again, thanks to all those who replied and offered great advice.

God bless,
Dave
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Old 02-24-2012, 10:02 PM   #30
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Well pump trips breaker at start, but then starts when breaker reset


You should not be using a GE breaker in a Square D Homeline panel.

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