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# 3 wires for well pump - all black

#1
05-19-18, 11:33 AM
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3 wires for well pump - all black

I've got a well pump that had wires cut/disconnected without labelling. The 3 wires are all black. How do I figure out which is which to splice it back to the motor control.
I can't easily do a continuity test since the splice point is 75m away from the motor control.

#2
05-19-18, 12:41 PM
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You have to do a continuity check.

Are the connection points labeled at the control ?
They should be something like S (start) R (run) C (common).
This must be done first.

Splice all three wires.
Go to pump control and disconnect the three wires.
Label the three wires A, B, C.
A-B= ohms ?
A-C= ohms ?
B-C= ohms ?

Post what you measure and we can tell you which wire is which.

#3
05-19-18, 05:39 PM
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Splice all 3 together at the cut point near the pump?
The wires are twisted the entire 75m length and buried so even if I know what they are at the control, if they're spliced at the other end, then I still need to figure out
A) which of the 3 is which from the source wire
B) which of the 3 is which on the pump
then splice those.
all the wires on the pump are black as well. Not sure which of the 3 to splice to the 3 from the control.

In the image c=control, p=pump

What's the background to the ohm test by the way? If I disconnect all the 3 wires at the control then why will the ohms be different. They're just 3 wires spliced together then?

Edit: I see what you mean. Splice the cut point and then test and the motor will show different resistances?

Last edited by qwertyjjj; 05-19-18 at 06:34 PM.
#4
05-19-18, 06:55 PM
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They are labelled black, yellow, and red on the control box.
R start
Y common
B main

#5
05-19-18, 07:05 PM
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Splice the cut point and then test and the motor will show different resistances?
Yes...... that is correct.

#6
05-20-18, 05:26 PM
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#7
05-20-18, 07:30 PM
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The three wires got cut midway between the submersible pump and the controller
and they are all black.

#8
05-20-18, 07:35 PM
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Then do the resistance test from the cut point to the pump and the battery test from the cut point to the controller.

#9
06-09-18, 06:10 PM
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I spliced them and am trying the resistance trea at the control box
My ohmmeter just jumps all over the place so I can't get a consistent reading between any of the 3 wires
. It's measuring AC voltage correctly so seems to be working unless the ohm setting needs a fresh battery.
Is there anyway to trial and error the wires or will it burn the motor?

#10
06-09-18, 06:31 PM
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Go to the lowest ohm scale. Usually Rx1. Make sure the meter zeroes out when you touch the leads together. If not.... change the battery.

You cannot guess by randomly connecting voltage without possible motor damage.