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Old 04-28-2010, 08:59 PM   #16
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well pump electrical multimeter question


Actually, you already have used the wire as a shunt.

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Originally Posted by tpolk View Post
I was able to check both sides of the 30amp double pole breaker and was reading 124 each leg.

checked the wire at the well and read almost exactly the same
What size wire are you using and how many feet between the breaker and your measurement point?

100' of #10 [50' for a two conductor cable] has a resistance of 0.1 ohm. 7A would drop the voltage 0.7V, so 248.0 v at your breaker would be 247.3v at your measurement point.
If you had very long test leads you could then measure the voltage drop on one 50' conductor, and it would be 0.35v corresponding to 7A. This way is much more accurate for measuring the current draw.


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Old 04-28-2010, 09:06 PM   #17
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well pump electrical multimeter question


100' of#10
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Old 04-28-2010, 09:29 PM   #18
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well pump electrical multimeter question


You can read the resistance of the motor, but what good will it do you?
The pressure switch sholud be wired with the incoming wires on the two outaide contacts, and the pump wired to the two inside contacts, or it could be wired the other way around.
Turn the power off and work the pressure switch by hand to see how it works.

With a deep well pump, there is not much troubleshooting you can do if everything up top works.
If you go through the trouble of pulling it out, you may as well replace it.
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Old 04-28-2010, 09:48 PM   #19
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everything new from press switch thru well pump last nov. guess i'm yanking the rascal should still be under warranty
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Old 04-28-2010, 10:02 PM   #20
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well pump electrical multimeter question


Do you have 240v going to the pump when it stops pumping?
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Old 04-28-2010, 10:28 PM   #21
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well pump electrical multimeter question


Here's my thoughts. The pump runs for 3 seconds. It's not seized.
There is still voltage on the cables to the pump when it stops running. That indicates to me one of two problems. 1. The pump is defective and cutting off on thermal overload. 2. Bad cable that is flexing with the pump torque and opening. Either one requires the pump to be pulled. Measuring the current might help. But it still going to lead to #1 if current too high or #2 if no current when pump stops.
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Old 04-28-2010, 10:37 PM   #22
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well pump electrical multimeter question


If you are testing the voltage on the cable to ground, then you will not
get a proper diagnosis.

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