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WATER PUMPS, TANKS, TESTS, WELLS, REPAIRS
CHEMICAL CONTAMINANTS in WATER
DRINKING WATER TESTING
DRINKING WATER - EMERGENCY PURIFICATION
PLUMBING SYSTEM INSPECT DIAGNOSE REPAIR
WATER CONSERVATION MEASURES
WATER CONTAMINANT LEVELS
WATER FILTERS, HOME USE
WATER HAMMER NOISE DIAGNOSE & CURE
WATER ODORS, CAUSE CURE
WATER PUMP REPAIR GUIDE
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER SOFTENERS & CONDITIONERS
WATER TANK: USES, TROUBLESHOOTING
WATER TESTS, CONTAMINANTS, TREATMENT
WATER TREATMENT EQUIPMENT CHOICES
WELLS CISTERNS & SPRINGS
WELL CHLORINATION & DISINFECTION
WELL FLOW RATE
WELL WATER PRESSURE DIAGNOSIS
WELL YIELD IMPROVEMENT
WINTERIZE A BUILDING
Well pump wiring diagnosis & repair:
this article describes troubleshooting a submersible well pump that was causing tripped circuit breakers and that pumped water only at a slow, reduced rate and pressure.
Ultimately using some simple electrical tests the homeowner traced the water pump problems to a nicked well pump wiring circuit wire.
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Electrical Wiring Damage Causing Water Pump Malfunctions: breaker or fuse trip/blow, poor or weak pump performance
My home well is doing some weird stuff. First of all, I have 25 amp breakers going to my 1.5 HP pump that is 160 feet down. in the last few days, it has tripped the breakers 5 times. I ohm ed out the motor and it is open (infinite resistance) to ground both legs and 3.2 ohms between the 2 leads going to the motor.
[Click to enlarge any image]
The symptoms that I am seeing is that it it taking my well about 7 to 10 minutes to fill up ( I have a 120 gallon galvanized tank with no bladder). When the water pressure in the tank gets to about 30 psi, the water in the house starts discharging air and water combined.
I have changed the starter cap. because the pump sounds as if it is working extra hard at start up, but smooth out as the pressure increases. changing the caps did not help. I was thinking that the caps may be bad and it was pulling too much current at start up and tripping the breakers. I'm not sure if the system is water logged or not. Any ideas?
Joe, Tripping breakers on the pump circuit often mean that the pump is drawing high current [or that there is an actual short circuit].
If we don't have a short in the circuit then unfortunately that makes us suspect a failing pump motor. Keep in mind that motor tests are tricky because once parts start spinning an internal winding can move, changing the electrical properties of the device.
For readers who are qualified and know how to use electrical test instruments, for safety and completeness also see
I'm speaking beyond my competence but from what I've been studying just recently, there are useful relationships between motor current draw and other conditions besides a failing motor.
Illustration at above-left: orange extension cord wiring used to hook up the pump pressure control switch is an improper and unsafe electrical installation.
So we could argue that a pump running against a waterlogged pressure tank might see higher than normal pressure but I doubt it. A water logged pressure tank will quickly if not immediately reach cut-out pressure and turn off the pump (unless the pressure control switch is itself faulty and not sensing that the tank is up to pressure). Anyway it's easy enough to check for a waterlogged tank, as we discuss in this article series.
I think I'd pull the pump and check for binding bearings, damaged impeller that's binding, and if those looked good I might take it to an electric motor repair shop for more expert testing.
Reader follow-up: successful well pump diagnosis traced to damaged wiring
Image at left, not from Joe's home, illustrates un-protected 240V wiring entering the well casing at the casing top of a water well located in a building basement.
I spent all day with it, watching it, listening to it. Here is what I found:
I was showing 238V at the cut off box at the control box. when the pump kicked on, I was loosing one leg and this was tripping the double pole breaker
. I tested this theory (I actually seen the leg go off with the meter) by taking my generator and hooking the 230V side up to the pump. I have a 7000 watt generator, so there was no issue running the pump. It took about 5 minutes to fill the 120 gallon tank.
It took forever [for the water tank pressure] to get past 25 psi, but once it hit 30 psi it took about 2 minutes for it to reach the cut off pressure of 68 psi (my pump and tank are quite a ways from my house and I adjusted the pressure). I had my wife and kids take showers, run the washing machine, and even used the sprinkler in the yard for a couple of hours and watched the pressure gauge and everything worked as normal.
With that being said, my power wire from the breaker box to the well is buried underground. I dug it up today and found a burned spot in the insulation. I cut the insulation back and found that the leg I was loosing when the pump came on was damaged.
I guess there was a nick in the wire when I buried it and didn't notice it. When the pump was not running, there was no current being pulled even though the voltage was still there. when current started passing through the wire, there was enough missing insulation to trip the breaker - like a ground fault on a 480V system.
I am an industrial electrician and I'm very familiar with 480V-2300V systems. I wasn't sure in my original post if I was seeing an issue with the air pressure in the tank or something along those lines.
Final fix: repaired bad wire going to the pump control box.
Well Pump Wiring Troubleshooting, Q&A
(Feb 2, 2014) tinner65 said:
my deep well pump has a concentric pipe running from the well to the pump. is the outer pipe just a sleeve for the inner pipe, or is there another reason for it?
Tinner, some installers run a larger diameter pipe to make it easier to replace a supply pipe or wiring in the future. The new lines can be snaked through the larger diameter plastic line. But I can't know for sure what you've got with no other description than your note. Take a look at the fittings, wiring, and water piping involved.
Continue reading at WATER PUMP ELECTRICAL SWITCHES or select a topic from the More Reading links shown below.
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