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I have ran underground ~40’ of 600V pvc ins. alumaflex 4way wire from code grounded 200A meter/load dist. combo box on permanent service pole to ungrounded 200A shop subpanel inside of shop. I don’t know if I should keep my neutral isolated from grounding to metal building since it doesn’t have a 8ft copper ground rod bonded to it or if it’s ok, meaning safe for me and my shop tools machines etc, and not really gonna require a lot more power usage for me to isolate neutral making it run the 40ft back

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  • What are you referring to when you mention "a lot more power usage for me to isolate neutral making it run the 40ft back"? The current has to make a complete circuit to and from the transformer no matter what you do; there's nothing you can do to make the neutral current not have to run the 40 ft back. Commented Dec 13, 2023 at 16:57

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There are three basic issues with grounding a subpanel in a separate building from the main panel:

  • Run a 4-wire cable (or 4 separate wires) - hot, hot, neutral, ground - from the main panel to the subpanel. "alumaflex 4way" sounds like you're OK.
  • Separate ground and neutral in the subpanel. That should be easy to do with a fairly new subpanel. 200A sounds more likely to be a "main panel" than a tiny little subpanel, but it really makes no difference. Just put neutral on neutral bars (as always), ground on ground bars (add a ground bar if you don't already have one) and remove any neutral/ground bond in the panel.
  • Install ground rods or ufer ground. Ufer ground (in concrete) is done when a building is built, so for a later installation the normal solution is 2 ground rods. Add them.

The distance doesn't really matter. The first two rules apply to any subpanel anywhere. The third applies when the subpanel is not in the same building as the main panel, which is obviously the case when the main panel is on a pole 40' away. Just add the ground rods - ~ $20 each + some 4 AWG copper wire and you're done.

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    I think you meant "third" in the 3rd sentence of the last paragraph.
    – Mark
    Commented Dec 13, 2023 at 5:36

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