Pump Inoperative

[Toby Hanson]

Hi all,

I put in a new pump a month ago, a 3/4 HP submersible. It's 90' down in a 100' well. It worked fine from that time until this weekend. I was out of town over the weekend with my wife and got a message from my sister saying the water was off. I got home today and started troubleshooting. One of the fifteen-amp fuses in the disconnect box was blown. I replaced it and closed the pressure switch manually. The pump came on for a few seconds but then it quit and won't come back on. I checked the fuses again and they're both good. I checked resistance on the wires to the pump and everything is within spec. I got a replacement capacitor for the control box just in case that was the problem but that didn't change anything. I traced the power path with my tick tracer and, with the pressure switch closed, there's voltage all along the wiring from the disconnect through the pressure switch to the control box and down to the pump. Even with the voltage on the wires the pump won't run. I've tried troubleshooting everything I know how to do on this system and I'm out of ideas. What else should I try?

 

[Reach4]

Use a voltmeter to measure the voltages at the control box. Measure L1 to L2. Measure black to yellow. Measure red to yellow.

Pull both fuses to make sure there is no power. Measure the resistance from the pump yellow to a ground.

 

[Sponsor]

 

[Toby Hanson]

Use a voltmeter to measure the voltages at the control box. Measure L1 to L2. Measure black to yellow. Measure red to yellow.

Pull both fuses to make sure there is no power. Measure the resistance from the pump yellow to a ground.

Here are the results:

Voltage, L1 to L2: 28.2 mV
Voltage, black to yellow: 0 V
Voltage, red to yellow: 0 V

Resistance, yellow to ground: 31 ohms
Resistance, red to ground: 41 ohms
Resistance, black to ground: 27.5 ohms

 

[Reach4]

Voltage, L1 to L2: 28.2 mV

If that was measured while good fuses were in, could have been good news. L1 and L2 should have 240 whenever the pressure switch is calling for water because the pressure is low. However the low resitance to ground is a problem.

Once you track down and fix the leakage to ground and restore power, measure the voltage into the pressure switch and out of the pressure switch:
If we call the terminals on the pressure switch A, B, C, D across.... then each of these should have 240 volts:
A to C
A to D
B to C
B to D

But first, ... the resistances to ground are way low. That could pop a fuse. So I expect that there is a popped fuse again.

Resistances to ground should be over 500,000 ohms. If it were 100,000 that would not be so bad. But your resistances are way low. Pull the fuses again, and disconnect L1 and L2 wires. See which still shows low resistance to ground. There could be a short down the well, in the wires to the well head, in the controller, before the controller. Divide and measure. Find the electrical leakage. I hope it is something easy to fix, like a cover or something that went thru the wire insulation.

 

[Toby Hanson]

If that was measured while good fuses were in, could have been good news. L1 and L2 should have 240 whenever the pressure switch is calling for water because the pressure is low. However the low resitance to ground is a problem.

Once you track down and fix the leakage to ground and restore power, measure the voltage into the pressure switch and out of the pressure switch:
If we call the terminals on the pressure switch A, B, C, D across.... then each of these should have 240 volts:
A to C
A to D
B to C
B to D

But first, ... the resistances to ground are way low. That could pop a fuse. So I expect that there is a popped fuse again.

Resistances to ground should be over 500,000 ohms. If it were 100,000 that would not be so bad. But your resistances are way low. Pull the fuses again, and disconnect L1 and L2 wires. See which still shows low resistance to ground. There could be a short down the well, in the wires to the well head, in the controller, before the controller. Divide and measure. Find the electrical leakage. I hope it is something easy to fix, like a cover or something that went thru the wire insulation.

Here are my results:

The voltage across any of the terminals at the pressure switch, with good fuses, was only 55 mV. That's almost nothing. I measured the voltage between the L1 and L2 after disconnecting them from the control box and got the same reading. I checked at the disconnect switch and also got 55 mV there. I'm thinking there might be a problem with the power supply coming from the main panel in my garage.

I then checked resistance to ground from the various wires going down to the pump. The numbers were all the same; every one was less than 40 ohms. I did a continuity test on all the pump wires to ground and the meter showed continuity which makes me think there's a short to ground somewhere. I'm thinking the next step will be to pull the pump and check the wiring going down to it. If there's no short in the wiring going to the pump then I can check and see if the short is internal.

 

[Reach4]

The voltage across any of the terminals at the pressure switch, with good fuses, was only 55 mV. That's almost nothing. I measured the voltage between the L1 and L2 after disconnecting them from the control box and got the same reading. I checked at the disconnect switch and also got 55 mV there. I'm thinking there might be a problem with the power supply coming from the main panel in my garage.

I would track down the resistance leak first. After that is resolved, check the voltage across the outputs of the two fuses.

I'm thinking the next step will be to pull the pump and check the wiring going down to it.

Not yet. Isolate the wires at the R, Y, and B terminals, and see which side (terminals or wire ends) show continuity. Alternatively do the isolation at L1 and L2. But the R,Y,B terminals are the last easy place. The next place will be to break the splices at the top of the casing. You want to try the easy stuff first. Remember to always remove power before checking resistances.

But pulling the pump may be happening after you eliminate the easier stuff.

 

[Toby Hanson]

I would track down the resistance leak first. After that is resolved, check the voltage across the outputs of the two fuses.


Not yet. Isolate the wires at the R, Y, and B terminals, and see which side (terminals or wire ends) show continuity. Alternatively do the isolation at L1 and L2. But the R,Y,B terminals are the last easy place. The next place will be to break the splices at the top of the casing. You want to try the easy stuff first. Remember to always remove power before checking resistances.

But pulling the pump may be happening after you eliminate the easier stuff.

I took all the wires off the control box and tested resistance to ground and continuity on the wires going down to the pump. Yellow -> ground: 4 ohms, black -> ground: 1 ohm; red -> ground: 14 ohms. There was continuity on each pair of wires. There's no splice at the well head. When I installed the pump I ran the wires through one of the vents in the well seal and directly to the control box. The only other splices in the wires is down at the pump where I spliced onto the pigtail coming out of the pump. I doubt there's a break in the wire insulation where it goes through the well seal because I wrapped the wires in several courses of electrical tape and ran them through a plastic bushing so the sharp edges wouldn't cut into the wiring.

EDIT: I forgot to mention earlier that I re-checked the voltage at the pressure switch. This time I got a proper 244 V. I didn't notice that the battery was nearly dead in my multi-meter last time I checked the voltage, which might explain the super-low reading previously.

 

[Reach4]

black -> ground: 1 ohm;

Hard short to ground on the black wire.

When I installed the pump I ran the wires through one of the vents in the well seal and directly to the control box.

That would be a good place for the short to be. I can picture the wire insulation damaged where it passes through the well seal plate.

 

[Valveman]

Hard short to ground on the black wire.

That would be a good place for the short to be. I can picture the wire insulation damaged where it passes through the well seal plate.

Yeah or it could be in the motor. You won't know until you pull it up and have a look.

 

[Reach4]

Yeah or it could be in the motor. You won't know until you pull it up and have a look.

It is possible that if he monitors the resistance to ground by wiggling the black wire at the well seal, he could tell. He would probably need a helper to watch the meter while he wiggles.

 

[Toby Hanson]

Problem solved. I pulled the pump out of the well and found the insulation had rubbed through on the black wire about three feet above the pump. I spliced the wire back together and put it back in the ground. It's pumping normally again. Thank you for all of your help troubleshooting!

 

[Valveman]

Now if you don't want that to happen again, you can add a Cycle Stop Valve, as cycling on and off is what causes the pump to torque and wear out the wire.