Pump motor compartment electrode

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Electromatic

Senior Member
Location
Virginia
Occupation
Master Electrician
I'm wiring two replacement submersible pumps for a municipal water station. In addition to the other wiring, each pump has a single-conductor cable that is apparently for an electrode in the motor compartment to detect seal leakage. I'm a little confused by the single wire, but it looks like the relay it goes to loops to ground to measure the resistivity. Do I have that basically correct?
Also, the factory cables will go to a junction box from which I need to extend the power and control conductors to the actual control cabinet. Do I need any special kind of wire to extend this electrode conductor?
 

Electromatic

Senior Member
Location
Virginia
Occupation
Master Electrician
I have a manual I got online for the general series of motor (Wilo FA10.34 T17.2). I doesn't mention extending wiring or not. It just says:
"Connect the electrodes via an evaluation relay. Relay “NIV 101/A” is recommended for
this. The threshold is 30 kOhm."

The factory cable is marked Prysmian Group H07RN-F 1x1.5mm2. I found a spec sheet for it, but it is all referenced to European standards, and I won't be able to get that specific wire.
 

Jraef

Moderator
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
1.5mm2 wire is essentially 16ga, I would use 14ga. That wire is rubber coated, here we often call it “pump cable” when there are multiple wires in a bundle. I would try to find some RHW individual wire.
 

Electromatic

Senior Member
Location
Virginia
Occupation
Master Electrician
These pumps actually came with 15-meter long power and sensor cables, but they would not reach all the way to the pump house control panel. We installed a junction box where they would reach. From there, I just used THH(W)N for the power and for the thermal and motor seal electrode sensor wires. The pumps were commissioned this morning, and everything operated fine. The municipality got new relays for the motor seal electrodes, but it was not in our contract to do anything with the control panel. I left it to them to make any necessary adjustments there.

Thanks as always for the feedback.
 
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