Electrical Troubleshooting Question
I have a pool pump that is tripping the breaker in the basement. 20A breaker, dual pole, 240 volts across the black and white wire.
I shut off all the switches in the pool house. Breaker still trips.
I removed all the wires from the underground cable in the box in the pool house. Breaker still trips.
I tried leaving just the black wire connected. Breaker doesn’t trip. Hook up just the white wire, breaker trips.
I found the junction box in the basement where the house wiring connects to the underground cable to the pump house. Disconnected the wires, turned on the breaker, breaker doesn’t trip.
Wired an extension cord to the cable to the pool and plug it in, GFCI trips.
Is there any doubt that I have a defective underground cable from the house to the pump house? Is there any additional trouble shooting I should do before I start digging? I think I have isolated the problem, but if there is anything else I can do before digging, I would like to hear it.
Thanks for any advice.
Replies
disconnect it at the pump house and keep checking ... might be something out there ...
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, wer ist jetzt der Idiot ?
You have a load that is grounding out. Something on the hot side is not properly isolated to the neutral side.
If you turn the power off to the 240 VAC circuit and then took a resistance measurement between the hot and neutral, you will find you have a low resistance. You have already started isolating the problem, you just need to finish finding the problem.
It could be the wiring on the hot run, but I might suggest that it is a load instead. What kind of loads do you have? Isolate them one at a time with the power OFF and take a resistance reading. When it goes up to infinity, you found the problem.
A lot of electrical problems can be found in a connection, not normally in a wire run. Or it is a load. Could of been something vibrated a connection loose and it is now touching ground.
> I tried leaving just the black wire connected. Breaker doesn't trip. Hook up just the white wire, breaker trips.
Sounds like somewhere the white has been connected to ground or to another white that isn't fed through the GFCI breaker. Remember, the white must as isolated as the black once it leaves the breaker -- can't be tied to any other whites.
You have said several things here that some of the other people have missed.
Also you said seveveral thing that aren't very clear.
"I have a pool pump that is tripping the breaker in the basement. 20A breaker, dual pole, 240 volts across the black and white wire."
So this is a 240 volt only circuit. No neutral and no 120 volt loads.
In a circuit like that the white wire is suppose to be remarked to show that it is a hot wire and not a neutral. Usually done by wrapping with black or red tape.
Is this just an overcurrent breaker or is a breaker that also has GFCI function? And if so can you tell the which caused it to trip?
"I shut off all the switches in the pool house. Breaker still trips."
How many switches and what do they operate?
"I removed all the wires from the underground cable in the box in the pool house. Breaker still trips."
Does that include the ground wire?
"Hook up just the white wire, breaker trips."
Again does that include the ground wire?
"Wired an extension cord to the cable to the pool and plug it in, GFCI trips."
To the pool or the pool equipement? And how did you make the connections a 240 extension cord is not common?
And what did you plug it into? Where is this GFCI?
It sounds like you tried to completely bypass the underground cable. If you did bypass the underground cable them this test shows that you have other problems (which might be a bad test).
Note that underground cable is not legal for supply pools, at least not for somekind.
http://www.selfhelpandmore.com/homewiringusa/2002/accessory/index.htm
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I removed all the wires from the underground cable in the box in the pool house. Breaker still trips.
I found the junction box in the basement where the house wiring connects to the underground cable to the pump house. Disconnected the wires, turned on the breaker, breaker doesn't trip.
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NO doubt at all. Jerk that suckka outa there.
SamT
[Meant for the OP] Do you have a multimeter? "Ohm" between the ground wire and the other two with the cable disconnected at both ends. If there's enough leakage to trip the GFCI you should read less than infinite resistance on one of the wires.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Edited 6/25/2007 11:28 pm by DanH
Thanks for the replies I've received so far. I'll try to clarify some points.
There is no load on the wires in the pool house because the troublesome wire has been disconnected from everything.
No, I did not disconnect the grounds when I was testing the circuit.
The two switches in the pump house that I shut off are breakers that control the two pumps (one main pump for filtering that runs a lot and one booster pump for the rolling vacuum that runs around the bottom of the pool when needed)
I connected the two wires to the pool house to a 120V power source via an extension cord only to see if I could get some power to the pool house. I plugged it into a GFCI outlet in the basement.
The interesting thing is that the pump was running two days ago. It seemed to be running poorly (pressure was low). I shut it off to check the strainer in case it was clogged. Strainer was not overly clogged, so I tried to restart the pump and that's when the breaker in the basement started tripping.
The fact that things were running makes me wonder if there could be another problem, although my testing leads me to think there is a problem in the cable from the house to the pool house.
two wires, Black and White on a 240v breaker ....it trips so you disconnect those two, fiddle around, and then power them up using a 120v extension cord.. how do you do that ?
how could just make one of them a neutral ?
is ithe bare ground your neutral ?.
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., wer ist jetzt der Idiot ?
I have just disconnected the grounds at each end of the cable to the pump house. Neither end of the cable is attached to anything. I used an ohm meter to check resistance between the white and the bare neutral. Zero resistance. I checked the resistance between the black and the bare neutral, it's very high (although not actually zero).
If there is any other conclusion to draw other than a short in the underground cable, I would like to hear it. I think I will be digging unless another solution presents itself.
The house was built in 1999, not when I lived here. Sticker indicates electrical was inspected an passed, so the use of the bare conductor as a neutral, which is what it appears to be, must have been legal at the time.
Yeah, the cable is toast. Likely it was nicked during installation, or has a factory splice that didn't get cut out like it should have. Or maybe a gopher or some such. (Have you done any digging or fence post setting in the area recently.)
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
This thread is confusing at the least. I read your initial post about 8 times to figure it out. So you have:
- 240 VAC circuit that supplies power to Two electric motors that drive pumps, that's the only thing on the circuit.
- It trips when the breaker is energized.
- You have close to infinite Ohms between the hot and neutral (you state it is very high, although not actually zero). You wouldn't have a neutral on this system, just two hot legs, this needs to be clarified. You state that between neutral and the bare wire you have 0 ohms which would indicate to me that this is a 120 VAC circuit or the white leg is part of a 220 VAC circuit and is grounded. Does it have a single or two pole breaker at the breaker box?
Personally, it sounds like a motor winding has failed, but need more information:
1. Is the wiring in a conduit, or is it ROMEX?
2. How is the wiring marked, sounds like black, white and bare. Check it at the breaker box, if the white and black both feed into a separate breaker, this would be the configuration for a 220 VAC circuit. If only the black feeds into a breaker and the white is tied to the common/neutral, it's a 110 VAC circuit.
3. Have you disconnected the motors at the junction box at the motor and energized the circuit to see if the breaker still trips? Do one motor at a time. If it doesn't trip, then it sounds like your wiring is good and the motor stator winding has failed (grounded out). If that is the case, you need to replace the motor.
If it no longer trips with one motor disconnected, measure the resistance from the hot lead of the motor winding to the bare frame of the motor. If the resistance is 0, the stator winding has failed and that is your problem. It should be very high (megaohms).
Can you post pictures of what you are trying to do? This is a very easy problem, but is very hard to understand, pictures would make it very easy.
from what he wrote, the bare ground is being used as the neutral for the black and white.... two separate hots out to the pump house and then one to each pump . along with a bare wire...sounds like the inspector missed it or whomever installed it pulled a fast one....
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., wer ist jetzt der Idiot ?
He never used the term neutral until well after other people had used that term.Paul kept using the term neutral."You have a load that is grounding out. Something on the hot side is not properly isolated to the neutral side.""If you turn the power off to the 240 VAC circuit and then took a resistance measurement between the hot and neutral, "And here he is not using the term consistantly.That is my I made very seecific comments and questions. But he did not verify them one way or anyother..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
you're right something was not adding up , I couldn't figure out how 240 or 120 could run a pump well I hope he at least ran 12/3 W G.
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., wer ist jetzt der Idiot ?
I would like to formally appologize and recall anything that I said that was incorrect.
:-)
A picture is worth a thousand words. And you are right, it probably was the motor running on 110 VAC versus 220.
any other conclusion? nope you will be digging...may as well replace the cable with three wire / ground.
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., wer ist jetzt der Idiot ?
One other thought: Before you rip up anything, carefully examine the cable where it enters the junction boxes at both ends, and make sure that there's no spot of skinned insulation or some such that could cause this.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
To all who replied, thank you for your assistance and patience.
I did what I should have done sooner, I ran a new cable above ground to the pump house. Everything works perfectly. I will start digging and burying soon. I know it would have taken less time to do that than the amount of time that has been expended here, so thanks again.
In addition, the pump now works fine, too, with normal pressure. I think that yesterday I thought I had a pump problem and then thought I had a coincidental line problem. I bet that the line was the whole problem from the start, and the pump was running poorly because it may have lost part of its power. I'm no electric motor guy, so who knows. All I know is that all is well and the obvious answer was the right one.
It may be that only half the double-pole breaker tripped, feeding 120V to the pump. It would still struggle to work, but would run slowly and would be apt to overheat.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Run in conduit this time, easy to replace if needed to again.
"The fact that things were running makes me wonder if there could be another problem, although my testing leads me to think there is a problem in the cable from the house to the pool house."It is possible for their to be a problem with the cable and pumps still work.All it takes is a small nick in the insulation and water getting into it to get enough leakage to trip a GFCI.You did not indicate 2 pole breaker was just an over current protection are if it was also a GFCI breaker.But even if it was only overload it is possible for a short to start developing between the one hot and grand and still supplying power ot the load.Depends on what kind of damage and just what is happening inside the cable..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Bill
It's not a GFCI breaker, but see my reply to Maddog, it certainly appears that I have a short between the white and bare ground in my feed to the pump house.
The cable could be undersized or have had a bad spot in it, and overheated.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Did anyone mention that UF cable isn't generally used for wiring pools? You refer to underground cable, so I'm figuring that's what you mean.
If you follow the NEC or some derivative of it then the approved method is to use wiring that has an insulated ground. This usually means conduit with individual conductors pulled through it. UF has a bare ground wire so is not approved for this use (the NEC refers to it as "covered").
This requirement kicks in where the wiring leaves the house and goes underground.
FWIW...................Ed
Edited 6/26/2007 10:04 pm ET by edlee