Meg Testing a Pool Pump Motor

[Little Bill]

Is it safe/ok to check a pool pump motor with a megohmeter?

If so what readings would be in the "pass" zone?

Had a customer call and ask me to check to see why his breaker is tripping for his pool pump. He said sometimes it will run for hours then trip and now he says it's gotten more frequent. Even to the point of only running a few minutes. He took it upon himself to put in a new GFCI breaker. He said that didn't help any.
I plan to check the current draw to see if I can catch it tripping to see if it's overloaded or not.
I thought if I couldn't catch it with my meter I would try a regular breaker to see if the tripping is on overload or ground fault. Of course this would be just to test and no one will be in or near the pool. If it still trips on the regular breaker I thought I could megger it but wasn't sure if it's ok to do that on a pool pump motor.
Now this pump is most likely a dual voltage motor. Meaning it can run off of 115V or 230V. It's been a while since I was there to remember for sure, but most if not all, the pool pump motors are dual voltage.

I'm assuming I would check:
hot to neutral
hot to frame of motor
neutral to frame

Any other ideas/suggestions?

 

[Tony S]

Test the cabling.

 

[Little Bill]

Test the cabling.

Actually I would be checking both at the same time since I would start at the end of the conductors that connect to the panel. Then if it reads poorly I would check each separately.

 

[ActionDave]

It won't hurt anything to megger the motor, hot to the frame, but if may not be worth the effort. I'd just use my amp meter, listen to the motor, and shine a flashlight inside to look at the winding to see if the lacing is in good shape.

Pool pumps lead a tortured life. Bad bearings, bad seal that leads to bad bearings, bad cap, bad starting switch would be my guesses. Unless you are hany with motors or close to a motorshop that will work on one that small it will be easier to just replace it. Except for the caps, those are easy to replace.

 

[Little Bill]

It won't hurt anything to megger the motor, hot to the frame, but if may not be worth the effort. I'd just use my amp meter, listen to the motor, and shine a flashlight inside to look at the winding to see if the lacing is in good shape.

Pool pumps lead a tortured life. Bad bearings, bad seal that leads to bad bearings, bad cap, bad starting switch would be my guesses. Unless you are hany with motors or close to a motorshop that will work on one that small it will be easier to just replace it. Except for the caps, those are easy to replace.

I hadn't planned on working on the motor. I just wanted to confirm whether it was the motor or not before he runs out and buys a new one.

 

[kwired]

Is it safe/ok to check a pool pump motor with a megohmeter?

If so what readings would be in the "pass" zone?

Had a customer call and ask me to check to see why his breaker is tripping for his pool pump. He said sometimes it will run for hours then trip and now he says it's gotten more frequent. Even to the point of only running a few minutes. He took it upon himself to put in a new GFCI breaker. He said that didn't help any.
I plan to check the current draw to see if I can catch it tripping to see if it's overloaded or not.
I thought if I couldn't catch it with my meter I would try a regular breaker to see if the tripping is on overload or ground fault. Of course this would be just to test and no one will be in or near the pool. If it still trips on the regular breaker I thought I could megger it but wasn't sure if it's ok to do that on a pool pump motor.
Now this pump is most likely a dual voltage motor. Meaning it can run off of 115V or 230V. It's been a while since I was there to remember for sure, but most if not all, the pool pump motors are dual voltage.

I'm assuming I would check:
hot to neutral
hot to frame of motor
neutral to frame

Any other ideas/suggestions?

Hot to neutral check means little as far as using a higher test voltage - if the motor is in working condition there will be rather low resistance between those two leads, if not you have an open circuit motor and it will not run at all.

Any reading below maybe 15-20 megohms to the frame and you have potential for enough leakage to trip GFCI's. If it is a submersible type of motor (not typical for pool pump motors) it may just have a leaking seal and needs seal replaced and dried out.

If you meg the cable and motor at the supply end and it tests good, not much need to further test motor. If it fails, you then need to go to the motor and separate from supply and verify which way the fault is. Also could be other components ahead of the motor that may be the problem, maybe not so much on a typical pool pump, but this was just general advice on megging, a hot tub maybe does have controls that may be the fault location.

 

[ramsy]

Any reading below maybe 15-20 megohms to the frame and you have potential for enough leakage to trip GFCI's.

I think you missplaced your decimals by a few orders of magnitude.

Didn't you mean below 0.15-0.2 megohms?

 

[kwired]

I think you missplaced your decimals by a few orders of magnitude.

Didn't you mean below 0.15-0.2 megohms?

Actually impedance to ground needs to be much lower then that, more like 30k if operating voltage is 120, for enough current to flow to trip a GFCI.

But experience tells me any reading in any kilo-ohms range is trouble and is either bad or needs dried out.

 

[Little Bill]

Customer is jumping ahead of me again!
He took a regular breaker and ran the pump off of it for 8-9hrs. He said it never tripped.
That was one of the things I was going to do but I wanted to do it myself to assure the breaker was installed correctly and to make sure to warn him not to let anyone in the pool, oh well.....

With that said, he told me although the pump ran it was noticeably louder than usual and thought he smelled a "burnt" smell. I told him there wasn't much use in paying me to come and do any further testing since it sounds like the pump motor is on its way south.
He agreed and is getting a new pump/motor. I will go and connect it for him but will check the wiring just to make sure before connecting it.

 

[kwired]

Customer is jumping ahead of me again!
He took a regular breaker and ran the pump off of it for 8-9hrs. He said it never tripped.
That was one of the things I was going to do but I wanted to do it myself to assure the breaker was installed correctly and to make sure to warn him not to let anyone in the pool, oh well.....

With that said, he told me although the pump ran it was noticeably louder than usual and thought he smelled a "burnt" smell. I told him there wasn't much use in paying me to come and do any further testing since it sounds like the pump motor is on its way south.
He agreed and is getting a new pump/motor. I will go and connect it for him but will check the wiring just to make sure before connecting it.

Did he install a higher amp setting breaker as well?

Sounds like possibly starting capacitor switch is hanging up and not cutting out a start capacitor. This shouldn't be a GFCI tripping issue but may cause enough current draw to trip on overload, but upsizing his replacement may allow it to continue running. But it also will only run a couple minutes max before the start capacitor fails - then it would likely continue to run sounding "normal" but would have no working start capacitor for the next time he tries to run it.

I guess replacing the motor may still be least cost option for the owner though, until the GFCI continues to trip and he finds out the motor wasn't the problem the first time:angel:

 

[Little Bill]

Did he install a higher amp setting breaker as well?

Sounds like possibly starting capacitor switch is hanging up and not cutting out a start capacitor. This shouldn't be a GFCI tripping issue but may cause enough current draw to trip on overload, but upsizing his replacement may allow it to continue running. But it also will only run a couple minutes max before the start capacitor fails - then it would likely continue to run sounding "normal" but would have no working start capacitor for the next time he tries to run it.

I guess replacing the motor may still be least cost option for the owner though, until the GFCI continues to trip and he finds out the motor wasn't the problem the first time:angel:

No, he just put in a SP 20A breaker which is what the GFCI was. He said it got so that the GFCI wouldn't even stay set for more than a few seconds.

There is no control circuit for the pump, no timer or anything, just straight from the breaker to the pump. I stated I would check his wiring before connecting the new pump. There is nothing else to check beyond that so I feel confident that the new pump and new GFCI breaker (that he already bought & installed) will take care of the problem.
I will also make sure the GFCI breaker is wired correctly as he put it in!:happyyes:

 

[kwired]

No, he just put in a SP 20A breaker which is what the GFCI was. He said it got so that the GFCI wouldn't even stay set for more than a few seconds.

There is no control circuit for the pump, no timer or anything, just straight from the breaker to the pump. I stated I would check his wiring before connecting the new pump. There is nothing else to check beyond that so I feel confident that the new pump and new GFCI breaker (that he already bought & installed) will take care of the problem.
I will also make sure the GFCI breaker is wired correctly as he put it in!:happyyes:

Why can't I get my customers to do all the work for me and all I do is check to see if it was done right