Ok smart problem solving people...

Ron

Ron

Dum Spiro Spero
Moderator
Joined
Apr 16, 2005
Location
Sharon, SC
All you smart nerdy engineer types
@shawn @jeepinmatt @Fabrik8 @6BangBronk
and a whole bunch more I'm probably forgetting.

:flipoff2:

Intermittent problem has been stumping me for a few days now.
House has a septic tank and it utilizes an effluent pump to move contents up to drain field.

Pump is a standard 120V style with integrated cord plug and plugs into gfi receptacle located at man hole.

First problem arose when septic backed up found gfi tripped. Wouldn't reset instant tripped. Ran extension cord to another GFI recep (testing to see if that particular GFI recep was bad) and same results. Insta trip.

At this point suspecting failing pump or possible cord/connection leak to ground issue.

Tank was full and had to pump down to investigate furthr...well didnt have to but strongly preferred to.

Plugged extension cord into dedicated 20A recep that is not GFI and pump performed dazzlingly and quickly pumped tank down to appropriate level. Breaker never tripped, extension cord never got warm. Pump ran for 30 solid minutes maybe 45. (septic tank is waaaay over sized for house. dont ask. builder is a dumbass. for those who have been here you know...so not an indication of a clogged pump or under performing it was working that whole time) until float switch cut it off and everything was as it should be.

At this point not really questioning motor anymore. Just cord/connection.

Plug back up to gfi outlet and stay fine. Manually fill the tank until floats kick pump on, pump runs fine. Will keep up with hose indefinitely. GFI never trips. So its looking like everything works until water gets too high and then it shorted the connection out and would trip the gfi once water level got to appropriate height (below electrical connection) gfi would power pump just fine.

Replace the failed high level alarm found the first time this screwed up and life is good.

For 3 days.

Today high level alarm goes off again and again I have a tripped gfi. Same routine. Wont reset, use non gfi to pump water down. Resets fine and works with float switch.

Something isnt right.

Pulled pump. No signs of damage to cord.

Disassemble connections and megger test the cord. Cord is good.
Take stinky motor to motor shop friend he tests the motor and says it is shitty but performing flawlessly.

Now what....
Thoughts.
Its not "just" a bad gfi as when the water level is high the GFI wont reset.
No visible fault path to ground.
Motor is fine.
I'm seriously considering just ditching the GFI and using a standard outlet. Ye sits outdoors. Yes technically its a wet location. Its under a waterproof outlet cover and inside a fake rock cover. Its dry "enough" top work just dont tell the code enforcement boogey man. :rolleyes:...But that's not the "right" answer. And my damn anal retentive ass likes to do things right...only I dont know what right is here.

Tell me what I've missed.

Oh yeah. Just for S&Gs I megger'ed the wire between the breaker and the post at the manhole cover and its fine as well.

And I had motor shop friend test my megger and its good.
 
Is the GFI 20A rated as well?

Is the GFI properly installed and grounded?

I'm slightly confused, when the GFI trips, it only trips when the motor runs, and not when the motor is first plugged into the outlet?

A GFI basically compares the supply and return current and trips if there is >5mA delta between them or whatever. If you've tested the cord and there's not appreciable resistance between the conductors and ground, it sounds like something is creating a minor current leakage path in the motor or switches. There could very well be a leakage path to ground that is small enough to trip the GFI but not large enough to interfere with motor operation. This might only happen when the motor is running and energized.

The other thing that could be happening is a pressure-related leakage path; the pressure on the pump is highest when the water level is highest, so something may be worn and touching if some part of the pump is deflecting under pressure, etc. Far fetched for it to be that consistent though.

It's interesting that it's water level related. Can't imagine it would have anything to do with the different dielectric constant of hose water versus um... regular tank contents. Can't be that much different for conduction.

Where are the switches (not the floats) with respect to the water level? Which are submerged or not submerged at the various states of water level?
 
Regarding it being level related, that made some sense to me as the connection/term point for both power on control is on top of the motor. So when it is over the top there could be current leakage through the terminals to the slop to earth, but after pulling the pump it was bone dry in the term box.

GFI is properly installed, and checked multiple ones. Eliminated that.

Actually Brian's post got me thinking about something. The float is a piggy back plug design and I did not test it. I wonder if there is current leakage through the float contacts. If the float housing is compromised ther could be crap (literally) getting inside and creating a short.

Great means I have to pull this damn thing, AGAIN!
 
Take the top of the pump off, look at the start up capacitor is it swollen? Signs of any heat? That is mostly what goes bad, FYI the motor will be filled with oil, it is supposed to! Good luck
 
Ron said:
Regarding it being level related, that made some sense to me as the connection/term point for both power on control is on top of the motor. So when it is over the top there could be current leakage through the terminals to the slop to earth, but after pulling the pump it was bone dry in the term box.

GFI is properly installed, and checked multiple ones. Eliminated that.

Actually Brian's post got me thinking about something. The float is a piggy back plug design and I did not test it. I wonder if there is current leakage through the float contacts. If the float housing is compromised ther could be crap (literally) getting inside and creating a short.

Great means I have to pull this damn thing, AGAIN!
Click to expand...

You can't create a short where there is already supposed to be one, if so (and shitwater has nowhere near enough conductivity to run the pump) then the pump would just turn on. You have a bad seal and it's giving you issues. Depending on how expensive the pump, I would just replace it--being that it has a piggyback float, it's probably not too pricey. I would also suggest a nicer pump and hard wire it to the panel sans gfci (or *cough* get rid of the gfci outlet). I've run into this more than to many times with ground fault outlets (expensive ones too) not liking sump pumps.
 
Refrigerators and freezers don't play nice with GFIs, too. Seems likely that the pump is leaking something back to ground.
 
Shitty situation.... All i have to add
 
Worn brush filings in the motor allowing for intermittent contact back to the case and tripping the GFI. Wouldn't take much. Not enough to trip a regular breaker, but would a GFI or AFCI....
 
braxton357 said:
You can't create a short where there is already supposed to be one, if so (and shitwater has nowhere near enough conductivity to run the pump) then the pump would just turn on.
Click to expand...

You don't need enough conductivity to run the pump, you just need enough for the GFI to detect 5mA of ground leakage and trip. That could happen with the pump running or not, depending on how the switch is connected in the circuit. I've never seen schematics for a effluent system like this, but it could be very telling...

Dunno, maybe none of those types of pumps are meant to designed to be used with a GFCI because of leakage?
 
You have a wire that has been juggled so many times that it has worn through the protective insulation. Sometimes it is ok, while other times (after a jiggle, it is not ok)

I'm not a nerd,nor did I read most of this thread.

But that is what happened to my well pump.
Wire was worn through, deep down,near the pump. Sometimes it would kick on, which causes movement and rubbing. It was kick the breaker. I could reset the breaker, and it would come back on, until the next" wiggle" then it would kick off again.
 
Fabrik8 said:
You don't need enough conductivity to run the pump, you just need enough for the GFI to detect 5mA of ground leakage and trip. That could happen with the pump running or not, depending on how the switch is connected in the circuit. I've never seen schematics for a effluent system like this, but it could be very telling...

Dunno, maybe none of those types of pumps are meant to designed to be used with a GFCI because of leakage?
Click to expand...
The float is just a switch loop with a steel ball or mercury inside that closes or opens two contacts and it is also the least likely place for a leak. Lower end pumps also are not oil filled so the chances of water getting in and causing problems are high. I'm my mind though it's like everyone has said, gfci outlets can have issues with large motors.
 
I'd still recommend exactly two things:
  1. Get a new GFI, because they're better than they used to be about nuisance tripping, and yours may be faulty with age. They do have a finite useful life.
  2. Get a new pump, because I still think there is something wrong and you have leakage current that you shouldn't have.
 
I'm no electronics guru, but it sounds like an inductive loading problem. Pump is a big motor, with higher load the inductive load is greater. Hence also why GFIs don't work well w/ things that have compressors (e.g. motors).
Either the inductive load of the pump had increased (worn brushes etc like you suggested) or the sensitivity of the GFI to it has increased w/ age so it trips now.
The cheap easy first thing to try as mentioned by Fabrik8 is a new GFI outlet. If that doesn't do it, you may indeed be looking for a new pump at some point in the future.
 
update
as stated tried this on multiple GFIoutlets and it does it on all of them. It isnt an outlet problem. There is current leaking somewhere to ground. However believe me, I'm well versed in the problems inductive loads cause with GFIs. However I'm also sensitive to the fact that should I change it to a non gfi, and something unforeseen happens and it causes damage, as a licensed electrical contractor who "knew better" insurance would probably leave me hung out to dry.

@broncosbybart ...I wish life was still that simple. If you know how to pick a basement up and move it Im all ears because Id relocate this bitch far away and build a decent house. Yes I said Basement. 12' ceilings and walk out. My back yard falls like a mofo. 42' of elevation change over 350' of run. The dumbass who built the house put the septic system in the front yard because...well because no one knows why. Even went and convinced the county to change their recommendation to put it in the front yard. back yard is 9 acres and backs up to 375 zoned AGR-Perm. No reason this damn system was designed the way it is.

@braxton357 my thinking with the float was simply that if water was getting inside the PLASTIC bulb :rolleyes: the switch contacts inside have exposed terminals. if it shorted the contacts together, then yeah pump turns on. But if current leaked into the water to the ground..then that would be a ground fault by definition and the gfi is doing its job. Again get the water below the float level and the gfi will cycle the pump dozens of times without tripping.

Im thinking I am just going ahead and replacing the pump, float and all. Its only 7 years old but seems the path of least resistance at this point. Anyone got a recommendation on where to buy one. This is the 2nd dauy of work Ive missed because of this mofo this week. On the good side, the new high level alarm worked and prevented another shitty situation.
 
This is far from my category of smartness... My brother is an electrician so usually just hit the "Easy" button and save those brain cells for other issues.

But I agree with RatLab that I too have had no luck with GFI's period for bigger items. I know for a fact that they trip on refrigerators, compressors and table saws. And that refrigerators make a hell of a mess when you figure out 3 days later that they tripped the GFI.

Which reminds me of a GFI to re-install when I put my house up for sale.:rolleyes:

I would try a known good receptacle not a GFI before throwing money at this. My guess would be that a septic pump would need to be on it's own circuit hardwired into the panel with the suggested breaker size.

Next possibility I'd check would be a bad wire grounding on itself or metal somewhere. I'd run a new wire straight to the pump and see if it works. I imagine new wire would be cheaper than a pump???

Again... No help here man. I've never had to deal with these. Good luck though!
 
I mean you can throw lots of money at it, but I'd just replace the GFI with a non-GFI. I also don't have the liability of being licensed.

There are also GFI breakers, but I don't know if that would make the situation better or worse. Might be worth thinking about, but in my mind, you would just have the same problem at a different location.

Something is happening between the low level cutoff and the high level alarm that is causing this, which would point to the float switch that brings the pump on.
 
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It sounds like it's been working for a long time on the GFCI, so I have a hard time blaming anything but the pump at the moment. It's the only variable that's changed recently if I understand correctly.
 
I would ditch the GFCI an just have a dedicated normal receptacle.

If you need to service, turn the breaker off.

GFCI are great in bathrooms and great in theory for garages and workshops. But they suck in damp location and starting motors and compressors.

Drag a good extension cord across dew covered grass and it's done....
 
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You quoted me before I deleted the post. Read 620.1. The scope says that only applies to elevator/escelator etc servicing equipment. I deleted my post because it dosent apply to residential.
 
Ron said:
House has a septic tank and it utilizes an effluent pump to move contents up to drain field.
Click to expand...

I can't offer any useful advice in this matter, but the key word here is "UP"...

...it all started about 40-45 +/- years ago when some st-o-o-o-pid sum-bush, who called himself an "in-jun-ear" decided shit could be run uphill. Since then... nuthin' but trouble. :shaking:

Good luck in solving your problem! :)
 
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