Electrical Mystery: Pentair Superflow Panel dead despite having 220 V input

[herder79]

Here is the mystery: My Pentair Superflow shows a dead panel. If I disconnect the hot wires from the pump, the voltage across them is 220 V, one hot lead has 120V to ground,
the other 100 V to ground. (due to some imperfect connections from the main panel to the pump).
However if the wires are connected to the pump the voltage across them is 0 V!!, but both have now 120V to ground!
Any help is highly appreciated.

 

[JamesW]

Do you have a timer or a switch controlling the pump?

Can you show what you have?

 

[JamesW]

However if the wires are connected to the pump the voltage across them is 0 V!!, but both have now 120V to ground!

One leg is probably dead and voltage is transferring through the pump.

Most likely a bad circuit breaker.

 

[herder79]

There is no timer, just the pump control panel. I check the circuit breaker, all ok. As I said both legs have voltage if disconnected from the pump. No dead leg.

 

[JamesW]

Disconnect the wires from the circuit breaker and check the voltage at the breaker terminals line to line and each line to ground.

Check the disconnected power wires for continuity to ground if you know how to do this safely.

 

[JamesW]

the voltage across them is 220 V, one hot lead has 120V to ground,
the other 100 V to ground. (due to some imperfect connections from the main panel to the pump).

That would take a serious defect to affect the voltage that much.

Most likely the circuit breaker is defective or the wiring is defective.

How old is the circuit breaker?

Is the CB GFCI?

 

[herder79]

 

[herder79]

Those are the leads at the pump which show 220 V if disconnected from the pump. Circuit breaker is not GFCI. Voltage at breaker is 240V across and 120V each to ground.
I will try to check continuity top ground.

 

[JamesW]

Voltage drop with no current indicates defective wiring.

Change the breaker to GFCI and most likely, the wiring needs to be replaced.

Do you have a different appliance you can put on the wiring as a test load to confirm if the power supply is the problem?

 

[JamesW]

A simple load test can be done with a Range/Stove element like this.

PRIVATE BRAND UNBRANDED 8 in. Universal Plug-in Range Element 464104 - The Home Depot

Use this replacement heating element to bring your existing oven / range back to its full cooking potential. These elements are compatible with most if not all the major brands on the market today. The

www.homedepot.com

4. cooking element power rating 240-Volt / 2100-Watt

This will put a 8.75 amp load on the line to see if there is a voltage drop under load.

If the line is damaged, load testing might be a bad idea.

The element gets hot, so figure out how to make it safe while it is being powered.

Only do what you are 100% sure that you can do safely.

 

[herder79]

On lead showed 200 KOhm on the continuity test. I agree that the wiring must be faulty. I will replace the wires and see what I get. Thank you!

 

[JamesW]

On lead showed 200 KOhm on the continuity test.

Is that from wire to ground or from one end of the wire to the other end?

Wire to ground should show O.L (Open Line). Any reading other than O.L is a fail and a ground fault, which is why you need GFCI on a pump power supply.

End of wire to end of wire should show the correct resistance based on distance and wire size.

For example, a #12 AWG copper wire at 100 feet should show about 0.19029 ohms end to end.

If the resistance is significantly higher, then that is a fail and the lines or connections need to be replaced.

For a load test, the voltage drop should be about 1.27% (3 volts) (240 volts drops to 237 volts) (12 AWG copper, 8.75 amps, 100 feet, 240 volts).

Higher voltage drop than indicated is a fail and requires addressing the failed components.

Any voltage drop with 0 amps load is a fail and requires addressing the failed components.

 

[herder79]

>Is that from wire to ground or from one end of the wire to the other end?
This wire to ground.

>Wire to ground should show O.L (Open Line). Any reading other than O.L is a fail and a ground fault, which is why you need GFCI on a pump power supply.
Agreed

>End of wire to end of wire should show the correct resistance based on distance and wire size.
Cannot measure since wire is buried.
I am in the process to replace the wires temporarily with new wires from an extension cord.

 

[JamesW]

(due to some imperfect connections from the main panel to the pump).

Seems like some known problems with the wiring.

What type of problems are known about the wiring?

 

[herder79]

Pool had a light which I had disconnected. I had to jury rig the connection in a wet location underground. I suspect this connection has gone bad.
Anyway after rewiring the pump works! Your suggestion to check connectivity to ground did the trick!
Now I need to put in new GFCI breakers permanent new wiring. Thank you very much!

 

[mknauss]

Your suggestion to check connectivity to ground did the trick!
Thank you very much!

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