240v Pump Trips GFCI Immediately

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Cybergy

Cybergy

0
May 23, 2014
116
Whitby, Ontario - Canada
I've had the same pump/GFCI breaker and wiring for 15 years now. Pump motor was rebuilt 2 years ago.

The pool is in-ground, 16x32, pump is 240volt protected by GFCI breaker at the panel, dedicated circuit. Wall-mounted outside by the pump is a power shutoff and a motor control switch to start/stop the pump. All equipment is open-air, but rated as such.

Pump has worked fine all season (past 3 months). We had heavy rain on Wed afternoon, I had the pump turned off at the time. After the rain stopped I went out to switch on the pump. Started fine, but a few mins later it was off. Now it will not start, as the GFI breaker trips immediately.

What I have done so far;
- replace the outdoor switch
- replace the GFCI breaker
- bypass the power shutoff box
- took the pump apart and had a tech check it out. Works fine, started up (mind you it's a dual voltage pump 120/240 he used 120)

What the heck else can I test/check? My pool is starting to turn on me, it's a long weekend and can't find an electrician. :confused:
 
Most likely some water got into the motor. With my 20+ year old pool I’ve also found water in the conduit and degraded wire insulation so I had to pull new wires.

Get a low cost digital multimeter and check for leakage resistance. The steps are:

Turn off the power to the pool subpanel
Turn off the pump GFCI
Turn on the pump switch.
​

Check the resistance between ground (the panel box) and each side of the pump breaker. This should be a minimum of 50K ohms and ideally well over 500K.

If you have < 50K Ohms, disconnect the wiring at the pump and check each line terminal to ground. Check the wiring for leakage to ground too. The problem will be at the pump, wiring or switch or all three.

If it’s the pump, let it dry for a few days, and check it again. If it returns to normal reconnect it, reinstall the wiring cover and seal the cover with silicone calk. If it's the switch or wiring you should just replace with new.

If you are not experienced working with 220V, call an electrician. You can be easily injured or killed.
 
CA92807 - I know how not to electrocute myself but I have no idea how to test for leakage, so your suggestion is fantastic - thank you!

I assumed the rain was the cause but I have completely disassembled the pump (except the motor itself) and saw no signs of water. Further, it worked just fine on the bench at the shop so I assume the difference is that the shop didn't have a GFCI and I do?

As I mentioned I replaced the switch, the breaker and bypassed the outdoor shutoff panel, so it has to be wiring - or still the pump itself.
 
Cybergy said:
I assumed the rain was the cause but I have completely disassembled the pump (except the motor itself) and saw no signs of water. Further, it worked just fine on the bench at the shop so I assume the difference is that the shop didn't have a GFCI and I do?
Click to expand...

Even with high leakage current (low resistance) the motor will run fine without a GFCI. You usually won't see any evidence except in extreme cases when it arcs, ruining the motor as plastic is turned into carbon from the heat.

You need a multimeter to isolate the root cause, but you don't need to pay over $20. Check out at Amazon. If you had a Harbor Freight nearby you can get one for free with a coupon.
 
Gotcha, so if the short is minute enough it won't trip a breaker but will trip a GFCI. I'll just wait and keep trying the pump. Hopefully it will start before the long weekend is over!

I've been using my multimeter all day but just checking for continuity where there shouldn't be. Will try testing for leakage tomorrow.
 
Well the numbers don't look good either way. Here's what I got testing between pony panel ground and each side of the GFI breaker (GFI Breaker OFF and pony panel breaker OFF);

Pump Connected, Pump Switch On
Red .9K ohms
Black .9K ohms

Pump Dis-Connected (at the pump switch - the "whip" was left connected to pump), Pump Switch On
Red 14K ohms
Black 33K ohms

The resistance is very low either way.
 
Disconnect the wires at the pump and check from each side of the line input to the pump case ground. If it's 900 ohms at the motor you have a major issue, perhaps insulation breakdown in the field coils. Small chance it could be a failure of the start cap, so disconnect that and check. Also a chance there is debris in the centrifugal start switch, if you have one.

The wiring from the breaker to the pump should really measure open from either side to ground. The GFCI should have no leakage to ground when open, but disconnect the wires and check just to be certain (I know, it's new). Your 15K & 33K measurement to ground is about what I had too, so I pulled out the wires and found water in the plastic conduit. The insulation had degraded and the line was leaking the ground wire. I used a pull rope with a long skinny rag at the end to collect the water (took several passes) and replaced the wires.
 
CA92807, I messed up my shoulder so testing is done for today :)

However earlier I had an idea to run from a regular, non gfi, breaker to see how the pump responded. It started and ran for about 30 seconds but was more noisy than normal, then the breaker tripped. I think it's the motor that's shot.

Thought perhaps when the shop tested it at 120v it only uses half of the windings as opposed to me running at 240?

Sent from my Nexus 7 using Tapatalk
 

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Well I got the news from the shop today - pump is internally grounding out and it's toast. No idea why it worked on the bench last week, but possibly due to the fact it was only hooked up to 120v.

I am now combing through the Pump forum posts for recommendations on a replacement.


Thanks for all the help on this one!
 
Sorry for the bad news. You still need to check out your wiring in the conduit. If there is still leakage between any of the wires or to ground with both ends open (as you indicated) you need to fix that.
 
The conduit has no water in it and readings on the lines show no issue, so I think I will be good to hook up the new pump when it arrives next week sometime.

I settled on a Hayward 1hp, 2-speed pump which cost less than $100 more than putting a new motor in the old one speed.
 
If the motor tech connected 120v source to test the motor, he would have to change some wires on the motor terminal board to run it at 120v, because you have a 240v connection, are you sure he changed the terminal board connections back to 240v after he tested the motor? you brought the motor to the tech with a known 240v motor configuration, because you have 240v source that you connect to it normally, that's obvious.

If he forgot to do that, it means you could have reconnected your wires, which supply 240v, to a terminal board set to run at 120v, which will fry the motor.

you can hook 120v power source to 240v motor, and it will run usually, but it runs slower, and will trip thermal overload circuit on motor, because the motor runs hotter.
you cannot run 240v power source to 120v configured motor, this may possibly explain why after 30 seconds, and unusual noise heard, was why motor fried. did it smell bad after it did this?

everything you describe as to original problem with g.f.i. tripping, most likely was moisture related (rainfall), g.f.i,s are very sensitive to water, and are specifically designed to trip at the slightest sense of it.

you said he was a "tech" most motor shops i know of have various voltage supply options where they bench test motors at, that clip on motor terminals, eliminating the need to alter terminal board to configure for 120v as in your case.

i think the tech may be responsible for what happened, what may have been a fluke moisture related issue, that would have dried, and possibly fixed itself, and stop the gfi tripping, has now left you with a fried motor, just my thoughts on what could have happened, without being able to put my eyes on it.
 
Cybergy said:
The conduit has no water in it and readings on the lines show no issue, so I think I will be good to hook up the new pump when it arrives next week sometime.

I settled on a Hayward 1hp, 2-speed pump which cost less than $100 more than putting a new motor in the old one speed.
Click to expand...

Please check the wiring for leaks as already recommended, they were suspiciously high (resistance too low) in your tests with pump off.
 
pool&spatech said:
...are you sure he changed the terminal board connections back to 240v
Click to expand...

I understand what you are saying but, I would say the point is moot now as I can't prove anything. I have no installation manual for the pentair whisperflo to confirm how to switch from 115 to 230. I just hooked up my friends old Hayward pump and there is a definite switch. I see nothing similar in my old dead pentair. There are two screw terminals and two wires connected to spade terminals. Think he put power on one screw and one spade. But I didn't see where he put his alligator clips.



Sent from my Nexus 7 using Tapatalk
 
max2k said:
Please check the wiring for leaks as already recommended, they were suspiciously high (resistance too low) in your tests with pump off.
Click to expand...
Hooked up my friends old pump and its running great, so if there's an electrical issue it's not tripping the gfi any longer.

It just seems to all point to the pump internally shorting out as was diagnosed at the shop.

Sent from my Nexus 7 using Tapatalk
 
I'd like to close the loop on this issue;

I was unable to sort things out before the winter freeze last season. Started up this spring and of course the tripping GFCI persisted.
I emailed Hayward. After telling them the house wiring showed no fault, they had a new pump at my door in 2 days (motor and control only - not the wet end). Completely different motor manufacturer and design. I suspect they had issues with the old design, because that was too easy.


New pump runs like a dream! No trips at all. Even through driving rain, etc.
 
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