GFCI tripping on pool pump motor

[pfactor2]

Curious if anyone has run into this issue. On a routine private inspection required by insurance company, the report noted the need for GFCI's pool pump motors on the property. One in particular ran fine for a week then would trip immediately. The existing system, from approximately 35yrs ago, had one liquid tight NM conduit with both the motor 208V 1/P and chemical feeder 120V circuits ran to a 3P relay box. I first did a megger check on the motor and it was borderline bad. Temporarily ran 12/2 Romex directly from the vac-pac panel to the line of relay essentially separating the the motor and chemical feeder circuits in separate runs. After this the GFCI did not trip, could I assume inductance was the culprit in this tripping problem? BTW
they elected to install a new motor since the existing was 5yrs old and they run 24/7/366 this year HA!

 

[ptonsparky]

Hard to tell from here but usually it's repeatable with inductive kickback. Cycling manually would cause a trip. After 35 years I would be megging everything. Borderline bad means replace it. Good call.

 

[Little Bill]

If the new pump they are getting has a VFD, chances are high the GFCI will trip on it as well. It has been discovered that Siemens
GFCI breakers work with some VFD pumps, Pentair being the main one.

 

[pfactor2]

Okay I guess you didn't thoroughly
Read the thread,
Bottom line if you did,
Could inductance from the 120volt/conductors being run in the same conduit with the 208volt motor cause a 2/pole GFCI on the motor to trip. No VFD installed. Just a simple Pentair 1stage 3hp 208volt pool pump.

 

[pfactor2]

Correction Single speed motor

 

[Little Bill]

I read it. You didn't mention whether you had a VFD or not so I was just pointing out that there is a well known problem with them tripping GFCI. I have no idea about anything else causing the trip.

 

[Fred B]

If the new pump they are getting has a VFD, chances are high the GFCI will trip on it as well. It has been discovered that Siemens
GFCI breakers work with some VFD pumps, Pentair being the main one.

OP doesn't indicate location, but NYS prohibits the sale of a pool motor that is not a VFD, VSD, type for energy ratings. So will be running into this more often around here. Have already had one that caused issue switched to a Siemens GFCI per mfg. recommendation and seems to be better. Pentair with Siemens have paired to make a GFCI still within class A, but less sensitive to VFD motors issues. (Per Siemens Rep.)