# pump trouble



## gcpl (Jul 7, 2012)

We installed a fuel dispensing pump about a month ago. 120 volt, about 3 amps running load, 180 feet panel to in ground pump, fuel dispenser is about 80 feet beyond the pump. All wired with #12 copper from a sq D QO panel. Breaker trips when the pump is running, not running, sometimes after the business is closed(they reset it in the morning), sometimes during the day they hear a click and its tripped. We monitored the circuit and no abnormal events, harmonics, volt surges ect. We have repulled the circuit and changed the breaker and still have the same problem. Anyone have any insight? Bad pump or fuel dispenser switch??? Thanks, Steve


----------



## nolabama (Oct 3, 2007)

gcpl said:


> We installed a fuel dispensing pump about a month ago. 120 volt, about 3 amps running load, 180 feet panel to in ground pump, fuel dispenser is about 80 feet beyond the pump. All wired with #12 copper from a sq D QO panel. Breaker trips when the pump is running, not running, sometimes after the business is closed(they reset it in the morning), sometimes during the day they hear a click and its tripped. We monitored the circuit and no abnormal events, harmonics, volt surges ect. We have repulled the circuit and changed the breaker and still have the same problem. Anyone have any insight? Bad pump or fuel dispenser switch??? Thanks, Steve


I can't imagine a bad pump tripping a breaker. I can't understand an off motor tripping a breaker. I cant understand a motor that can start and run on a breaker tripping it. I can't see three amps opening a thermal in a breaker. I can see something binding the pump causing the motor to lock and that opening a breaker. I would have to assume this is a single phase pump with no real motor control circuit.


----------



## Big John (May 23, 2010)

What does "monitored the circuit" mean? If you were monitoring current you must've seen an overload of some kind?

It sounds like an insulation failure in the run somewhere. That it's intermittent makes me think not the motor windings, but maybe even the leads to the motor since you already replaced the underground: Something in the environment changes, temperature, moisture, vibration, and suddenly you've got a ground fault.

Own a megger?

-John


----------



## wendon (Sep 27, 2010)

Why would the breaker trip on motor overload when no one is running the pump. Is the pump being used after hours or is the whole system offline after hours. I would suspect something between the breaker and the control.


----------



## Big John (May 23, 2010)

wendon said:


> Why would the breaker trip on motor overload when no one is running the pump...


Figure of speech. Overcurrent.

-John


----------



## wendon (Sep 27, 2010)

Big John said:


> Figure of speech. Overcurrent.
> 
> -John


What I meant is why would the breaker trip when no one is running the pump. There wouldn't be any voltage on the underground conductors when the pumps aren't in use. Or am I missing something? Is it possible that a relay is arcing or something of the sort?


----------



## nolabama (Oct 3, 2007)

that off motor breaker opened part throws me too

cant wont aint gonna understand that
must have a powered control circuit that is opening the shared over current for the motor 

this is why i tink the control circuit aint right

if its a simple switch tho who knows


----------



## gcpl (Jul 7, 2012)

It is a single phase motor with its own thermal protection. To monitor the circuit we have a power quality monitor that we installed for a day and did not see anything unusal, but it samples every half second, and may have missed an event if it was shorter. Would arcing at the control circuit(the pump) cause a breaker to trip below its rated ampacity?


----------



## gcpl (Jul 7, 2012)

The breaker is a standard QO bolt on, no gfci protection.


----------



## Big John (May 23, 2010)

The fact that this is intermittent and it continues after you replaced the breaker suggest it's not a poor connection at the breaker itself.

If your controls are really out of whack, and for some reason your pump is short-cycling (even when off :confused1 then you could trip the breaker on thermal or magnetic, but you would've almost definitely seen that on your monitor and I would expect other indicators as well.

That's why I'm leaning towards the the ground-faultsomewhere; it seems like the simpler answer. And you would also be lucky to capture an instantaneous magnetic trip while only recording every half-second, so I'm not surprised that didn't happen.

-John


----------



## John (Jan 22, 2007)

Did you try changing the breaker? Did you check the panel?


When you have unexplained events happening.....assume the who ever was there before you did it wrong. :whistling2:


----------



## gcpl (Jul 7, 2012)

Thanks for all the insight. We did swap breakers twice and had the same problem. Last Friday, after reading all the posts, I mounted a 30a fusable pullout disconnect on the side of the panel, fused it with a 20 amp time delay fuse, and hooked the pump circuit to the load side. The were open all weekend(car dealership) and the pump worked fine. The pump is controlled with a franklin controller, which monitors three sensors at the tank and allows the pump to run. Big John, you mentioned a magnetic trip problem. What is that, I am not familiar with that?


----------



## Big John (May 23, 2010)

Magnetic trip is just a function within the circuit breaker when it sees short-circuit current. Instead of tripping by heating an element within the breaker, there's enough magnetic force generated to move the trip element.

Can you post what type of fuses you installed?

-John


----------

