GFCI protection on a residential well pump.

My cousin called me last week. One of his relatives is building an addition and they are installing a new well. The Well Co is on site and they hit good water at 130 feet. They are using a submersible with a VFD control so I guess no pressure tank is needed as the pump ramps on the VFD to control the pressure. The house is on a mountain top that gets lightning. The house has lightening protection.

Anyhow, the well company has the pump installed but no wiring yet so they had a generator and were trying to run the pump off the Gen and it wouldn't work they wanted to test the well.

I told him a lightning strike or if they loose power (which they do) and go on their gen they my not play nice with the VFD. i would go with a pressure tank and a switch but that's just me.


The well installers were complaining about their boss who loves the VFDs.
 
Eddie702 said:
My cousin called me last week. One of his relatives is building an addition and they are installing a new well. The Well Co is on site and they hit good water at 130 feet. They are using a submersible with a VFD control so I guess no pressure tank is needed as the pump ramps on the VFD to control the pressure. The house is on a mountain top that gets lightning. The house has lightening protection.

Anyhow, the well company has the pump installed but no wiring yet so they had a generator and were trying to run the pump off the Gen and it wouldn't work they wanted to test the well.

I told him a lightning strike or if they loose power (which they do) and go on their gen they my not play nice with the VFD. i would go with a pressure tank and a switch but that's just me.


The well installers were complaining about their boss who loves the VFDs.
Click to expand...

My VFD well has had no problems on my Generac whole house generator.
 
solar-dr.com said:
Need some help, Inspector is requiring all well pumps to be GFCI protected. Sighting 210 8 (F) in the 2023 NEC code. This code only pertains to a receptacle, not a well. He claims it is utilization equipment. The code will at some point make a well pump GFCI protected but as of right now it is not required to be GFCI protected, please give your argument either way because I believe the building department is mis interpretating this code.
Click to expand...
Article 100
Outlet: A point on the wiring system at which current is taken to supply utilization equipment
 
solar-dr.com said:
what about 210 .3 where it refers to 430 for motors?
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In the 2014 and older codes, nothing in 210 applied to motor circuits as the scope said:
210.1 Scope.
This article covers branch circuits except for branch circuits that supply only motor loads, which are covered in Article 430. Provisions of this article and Article 430 apply to branch circuits with combination loads.
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In the 2017 and newer codes, the rules in 210 apply to motor circuits unless modified by rules in 430. Nothing in 430 modifies 210.8(F).
 
Eddie702 said:
My cousin called me last week. One of his relatives is building an addition and they are installing a new well. The Well Co is on site and they hit good water at 130 feet. They are using a submersible with a VFD control so I guess no pressure tank is needed as the pump ramps on the VFD to control the pressure. The house is on a mountain top that gets lightning. The house has lightening protection.

Anyhow, the well company has the pump installed but no wiring yet so they had a generator and were trying to run the pump off the Gen and it wouldn't work they wanted to test the well.

I told him a lightning strike or if they loose power (which they do) and go on their gen they my not play nice with the VFD. i would go with a pressure tank and a switch but that's just me.


The well installers were complaining about their boss who loves the VFDs.
Click to expand...
They still have a small tank for expansion reasons, water won't compress and pressure will change too rapidly if there is no expansion tank.

I had a new site earlier this year, well was already installed with a hydrant near the well. Concrete guys wanted to be able to run the well for cleaning tools but of course I had no power yet, not even to the house as it was still at the footings stages and the main pole was 300 feet away. I told GC if he wanted it now it would have to be run from a generator. They could not get it to work. I looked at the fault code on the drive - "voltage too high or too low" I checked generator output volts was over 260. My guess they set it a little high in the past thinking it gave them more umph. Backed off minimum speed set screw on generator carb and well took off. VFD usually aren't too picky on quality of input volts, as long as it isn't' a condition that leaves too high or too low DC bus voltage. Even a short time ripple in DC bus could trip it, it is only trying to protect itself when it does this.
 
I think NEC needs to re-evaluate 210.8(F). Conventional submersible run directly across the line maybe is OK to protect with GFCI. It is at least a little more doable not saying you still won't have potential leakage issues and maybe this should at least require 30mA GFPE instead.

But a submersible driven by a VFD should be exempted. First there is no way to add a GFCI between the drive and the motor. The drives are good at responding to low level ground faults and locking out when fault is detected anyway. May not meet class A GFCI standards but still very good at detecting faults you can't even measure with a DMM. The drives do this for self protection if nothing else.

GFCI protection on the input side of the drive? If they get the GFCI's to work with the VFD driven HVAC units then they should be able to work with these drives as well. Still doesn't provide any protection to load side of the drive as it is essentially separately derived from the supply circuit.

Don't get me wrong, more attention needs to be put on safety of some this equipment. Been 20 years or better now, but a 9 year old girl was electrocuted in my county when she contacted the above ground portion of metallic "pitless adapter" of a well casing. IIRC they found the cable running to the well had been damaged by some excavation at some time before the incident and the repair resulted in compromised EGC that likely would have tripped an overcurrent device had it not been compromised.
 
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