Septic pump keeps blowing fuse

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Stevenfyeager

Senior Member
Location
United States, Indiana
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electrical contractor
My customer has a two year old septic pump that blows a two amp fuse. The installer has replaced the two pole switch a couple of times in that time. He did a load test 11 amps on the 240 volt Zoeller pump ( one year warranty). Bad deal, his house has to shut down water usage each time. :( FLA is 10.5 amps, locked rotor amps 44 amps. Thank you !
 
On the few that I have worked on that have a control fuse, other than internal components, the fuse protected the float switch.
I would carefully inspect the wiring tom the float(s).
 
augie47 said:
On the few that I have worked on that have a control fuse, other than internal components, the fuse protected the float switch.
I would carefully inspect the wiring tom the float(s).
Click to expand...
It is still blowing the fuse, even with a new contact switch and fuse. I'm not sure the installer inspected the wiring to the float yesterday. The septic installer says the salesman says "when the pump kicks on there is a very high spike in the low voltage terminals."
You think the problem is in the float or the electronic control panel ? I think he replaced the outside control panel last year already. Thank you !
 
Stevenfyeager said:
It is still blowing the fuse, even with a new contact switch and fuse. I'm not sure the installer inspected the wiring to the float yesterday. The septic installer says the salesman says "when the pump kicks on there is a very high spike in the low voltage terminals."
You think the problem is in the float or the electronic control panel ? I think he replaced the outside control panel last year already. Thank you !
Click to expand...

It stands to reason if the the control fuse is blowing, you have a control circuit problem. Disconnect the leads to the pump itself. Less confusion. Don’t rely on what the “installer says the salesman says”. Check it out yourself.
 
A control component issue to look at is if the float switch is set wrong or is malfunctioning, it may be “bouncing” and chattering the pump on and off. That will eventually blow the control fuse, hopefully before it damages the pump and/or contactor.

It is remotely possible that if the wiring to the sump pump is undersized, the inrush of the pump motor is causing an overall voltage drop that is so severe that it causes the control circuit to pull more current an blows the fuse. I would still suspect a bad control circuit issue first, but watching the voltage while the pump starts may give you a clue.
 
Without knowing anything about the setup and hearing a control fuse is blown. I'd see if the float system is tied to this fused circuit. When floats wear out and go bad, often times moisture has entered the float and will blow fuses. I've seen it many times. But, there are many other things it could be as well.....

A megger can help make short work of these problems.
 
Stevenfyeager said:
My customer has a two year old septic pump that blows a two amp fuse. The installer has replaced the two pole switch a couple of times in that time. He did a load test 11 amps on the 240 volt Zoeller pump ( one year warranty). Bad deal, his house has to shut down water usage each time. :( FLA is 10.5 amps, locked rotor amps 44 amps. Thank you !
Click to expand...


Is it an ejector pump?
 
Cow said:
Without knowing anything about the setup and hearing a control fuse is blown. I'd see if the float system is tied to this fused circuit. When floats wear out and go bad, often times moisture has entered the float and will blow fuses. I've seen it many times. But, there are many other things it could be as well.....

A megger can help make short work of these problems.
Click to expand...
I have a megometer, and have only used it to test heated floors, other than that I don't know how to test this situation. I wish I knew more about circuitry and electronic control boards...
 
Stevenfyeager said:
I have a megometer, and have only used it to test heated floors, other than that I don't know how to test this situation. I wish I knew more about circuitry and electronic control boards...
Click to expand...

Disconnect the float wires. Meg to earth or ground as you would the floor heat in both the upper and lower position. With the float in the lower position meg between the two conductors.

Do not meg the control board.
 
Stevenfyeager said:
I have a megometer, and have only used it to test heated floors, other than that I don't know how to test this situation. I wish I knew more about circuitry and electronic control boards...
Click to expand...

You are not going to repair an electronic board. As far as any circuitry that needs troubleshooting, hot, switch leg, and common is all there is whether it's a light switch or a motor control.
 
I would replace the pump and the controller. How much time has been spent on this job. It is a labor vs. parts situation.
 
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