VFD on submersible pump in a body of water

[kwired]

The constant velocity pump is also known as a constant pressure pump and is using a pressure xducer for feedback. The pump motor that was installed is a single phase and the controller will be for a 3 wire single phase motor which is configured for residential pump control. The motor and drive are seperate devices on this system.

My mistake on this installation was assuming that the ground fault detection on the drive was sufficient to meet rule 26-956 but in discussions with Pentair there is no defined specification at which the ground fault detection occurs - could be 1A or more. Of course this is not acceptable.

At this point I will most likely install system with a GF breaker feeding the standard start/run winding relay and motor. There is a large market for this VFD application if there was a safe and accepted solution.

Is likely safe enough, problem is NEC throws in a requirement kind of out of the blue for GFCI protection for things that haven't yet been evaluated for use on GFCI's, based on just one real world incident and a bunch of speculation about many other similar situations. These items weren't normally required to have GFCI protection in the past and therefore not required to pass same leakage levels for listing requirements.