Grounding of Pipes Coming out of Submersible Well in PVC

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donjohn

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Can anyone tell me if the NEC requires that the metal water pipe coming out of a submersible well (casing is PVC) is required to be grounded as it comes out of the wellhead? The submersible pump motor is a 5 hp 3-phase 480 volt and is approximately 320 ft. deep.
donjohn
 
Grounding of metal pipe coming out of submersible well

Grounding of metal pipe coming out of submersible well

Thanks for your assistance. The way I read your response is that the pipe, as it leaves the well head should be grounded, especially if the well casing is PVC. Is this addressed specifically in a particular section of the code? Should the pipe be grounded to a driven ground rod right at the well head and should the pipe also be bonded to the grounded conductor of the electrical service as it also leaves the well head? I have always assumed that the grounding should be this way but I haven't had any luck finding a direct statement within the code that directly relates to this situation. Anyway thanks for your assistance.
donjohn
 
Don
Is this metal pipe continued on underground to the building or is this just metal fitting that are used to go from nonmetallic to nonmetallic piping?

If it is indeed a metal piping system that has 10 feet or more in direct contact with the earth then it is part of the electrode system and is to be bonded using table 250.66 as outlined in 250.52(A)(1).
If this is just fittings that are used to make up the nonmetallic piping then it can be bonded to the equipment grounding conductor that supplies the pump as outlined in 250.104.

A driven rod would not hurt anything but it won?t help anything either as outlined in 250.4

Remember that the equipment grounding conductor is installed to open the overcurrent device in the event of a ground fault. Installing a rod that ?might? make the 25 ohms as mandated in 250.56 will not open the circuit that is supplying the pump.
Using Ohm?s law and one leg of the 240 volt circuit that is supplying the pump (assuming it is a 240 volt pump) the rod will only draw 4.8 amps, not enough to open the overcurrent device supplying the pump.
The only good the rod would be is in the event of a lightning strike.
 
Is this a service or a feeder? It doesn't matter if the casing is metal or plastic it (the pipe) needs to be bonded to the gounded conductor if this is a service or the grounding conductor if a feeder.

Does the pipe fit the description or requirements of 250.52(A)(1)? If yes, keep reading, you will find the answers.
 
Grounding of Well Pipe

Grounding of Well Pipe

Mike,
Thanks for your reply. In this instance the submersible well is approximately 320 ft. down the well. The well casing only is PVC. The metallic pipe continues down the well and supports the submersible pump. The pump motor is a 5 hp 3-phase 277/480 volt and the grounded conductor of the 4-conductor wire is only bonded at the motor itself and only again at the pump electrical panel. As the metallic pipe exits the well head it extends about 3 ft. out of the well head and non-conductive hoses running to a well drilling pit, are connected to the metallic valves on the end of the pipe. As the pipe leaves the well head it does not make contact with the earth at all although the pump and the pipe at the bottom of the well are in probably about 30 ft. of water, which naturally is in contact with the earth. We have a well drilling contractor that is installing these submersible wells in without any grounding other than on the pump connection and the pump panel, which is roughly 40 to 50 ft away from the well head, and I believe that it is a violation of the NEC. It appears from my reading of the NEC that the pipe as it comes out of the well head should be bonded to the ground conductor of the electrical service wire and also to a driven ground rod at the PVC casing. But again, it doesn't state this directly. Anyway, what do you think?
Don
 
Hello, Don. If the rod isn't effectively bonded to the rest of the Grounding Electrode System, the rod will serve to ensure a high voltage gradient exists during a lightning strike on the system with the pump system (pump, phase conductors, OCPD) taking the full brunt of it.

The pipe and rod, if meeting the descriptions of 250.52, would be connected to the grounding electrode conductor, not the grounded conductor.

On a 480V grounded-wye system, the ground rod at 25 ohms draws 11A. The grubs and earthworms hate it, but it's not the fault path you want the current to follow back to the service. For the pump motor itself you'd have an equipment grounding conductor running in parallel with the phase conductors all the way back to the panel, sized sufficiently (as are the phase conductors) so that a ground fault at the pump would pass enough current through the EGC to clear the OCPD quickly.

As ptonsparky and jwelectric said, you'd also have to run a bonding jumper back to the grounding electrode system if the pipe and rod conform to 250.52. I'm not positive on this, but I don't think it's kosher to make the EGC pull double-duty as a bonding jumper to the GEC, so you'd need separate bonding.

If I typed any slower I'd be pushing daisies.
Is the fourth wire acting as the neutral on a wye-connected motor, or the equipment grounding conductor?
Regards,
Dan
 
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As you describe it, this pipe is not part of the grounding electrode system. The equipment ground to the pump is allowed to bond equipment that may become energized and only at the pump end is adequate. That said, I would certainly like a bond on the top side but the installer is meeting minimum.
 
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