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I am placing an unattached breaker panel in a well house to be run from a generator. I realize that I need a grounding rod for the ground, but since it does not have a ground for the neutral bar does this need a second grounding rod? I have read several discussions but they only speak of the path going back to a house or transformer. Since there is no path for the neutral to a ground in an unattached building is a # 6 coated wire attached to the panel neutral bar an option. So , by using two ground rods six feet apart one a bare wire to the panel case and the other to the neural bar would this keep me from shorting out my generator and myself?

  • Is the generator the only power source for this shed? – ThreePhaseEel May 26 '18 at 4:38
  • Also, is the well casing metal? – ThreePhaseEel May 26 '18 at 4:38
  • And is this generator going to be a portable generator corded to an inlet, or a permanently installed generator? – ThreePhaseEel May 26 '18 at 4:42
  • How does the well get power? – Harper May 26 '18 at 5:33
  • Yes the generator is the only power source also the well casing is old and unknown if it is metal or pvc it has a twenty inch cemented top with a five inch Center that has a 1 1/2 metal pipe with the submersible pump at attached, depth unknown without pulling it. The generator is a Miller Bobcat 250 portable on a trailer not grounded to the trailer. I use for repair welding. The well at one time was connected to a main panel at an old farm house but is now disconnect for demolishment. So the breaker panel is unattached. I have read what has been posted about NEC 250.30. – Rick May 26 '18 at 15:22
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How to handle this

I'm going to presume that there's a panel here (if not, I'd slap a decent-sized main breaker loadcenter in there, a Siemens P3030B1100CU would be my starting point, and then add the appropriate breaker for the well pump and hook it up), and that we don't have to worry about the generator itself -- it has overcurrent protection in the form of a circuit breaker built in.

As a result, we can simply pull the bonding screw on the loadcenter/panel, and then wire a generator inlet box (locking type, 50A, 120/240V) to it using a 6/3 UF cable such that the hots land on each hot leg of the main breaker, the neutral lands on the main neutral lug, and the ground lands on the main ground lug -- if the panel has no ground bar in it, you will need to add one. The inlet box will mount to the outside of the shed, by the way (this saves the generator cord from having to be run through a door or window frame).

Once you're done with that, you can then run 6AWG copper from the panel to two driven ground rods, spaced 6' apart, as well as a length of 6AWG copper from the panel to the well casing if the well uses a metal casing. This takes care of the grounding electrode system.

Once all this is done, you simply take a 50A generator cord, plug it into the generator power receptacle and the inlet, and all should work. Since things are in a separately derived system configuration, you don't have to fuss with the bonding jumper in your generator at all, and if you want to replace the generator inlet with a permanent feeder in the future, the panel's already configured for that.

  • Although a main breaker is usually a good idea I don't know if I would waste the $ on that the generator has a breaker and if it is turned off there is no power so the only the need breaker is the one sized for the pump.Other than that I fully agree. – Ed Beal Jun 5 '18 at 7:20
  • @EdBeal -- part of the reason for the main breaker panel is to make it relatively trivial to change this over from being a generator setup to a permanent feeder in the future. – ThreePhaseEel Jun 5 '18 at 11:23
  • I do understand the reasoning and gave an up vote but depending on OP future plans if any they may want to save a few bucks. – Ed Beal Jun 5 '18 at 14:53

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