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I had a well pump installed and in the process discovered the significance of tying all metal surfaces together by EGCs to provide a path back to neutral.

Diagram is attached for reference.

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The neutrals and grounds throughout all subpanels are bonded. There is a single ground rod tied into neutral bar at utility pole.

There is no ground wire in the system - equipment and appliances are simply "grounded" through their neutral wire.

Much of this can be rewired, or a separate ground wire added. What won't happen is a ground wire running from the point of first disconnect (utility pole) a thousand feet to the farm buildings.

The main line from the pole is spliced(split) to go to two different buildings.

    • There is no required electrical code for this rural installation. - -

I'm not 100% clear on this, but it seems one way to retrofit would be to ground and bond to neutral at each of these second disconnects. Then the only danger of losing path of low resistance back to the source would be if the neutral wire from these two second disconnects were to be broken.

And then of course I would isolate ground from neutral for all other subpanels and circuits.

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  • Think in most places they use one or two ground rods for each building and ground that way, not with a long wire back to a far ground rod. They also separate the ground and neutral in the sub panels.
    – crip659
    Jan 29, 2022 at 18:18
  • How many amps is this service, and who's your utility? Jan 29, 2022 at 20:11
  • There's a 100A breaker underneath the meter. Its never been tripped. The utility is the county electric co-op?
    – Andrew
    Jan 29, 2022 at 20:25

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I agree with not attempting to retrofit ground to the utility supply due to sheer impracticability. You can lean here on the fact that you are probably grandfathered due to the work having gone in prior to "separate ground" becoming Code.

Yes, I were you, and you feel comfortable retrofitting a ground conductor between greenhouse and utility shed, I would treat the farm shed and utility shed as if the main breaker was there, for purposes of bonding and grounding.

So I think your plan is fine. But as far as the reasons for grounding/bonding, there's more than what you just said. But the most important part is that there be ground rods local to the buildings; I don't see a "win" in spending a lot of money to add a ground rod 1000' from your buildings where there's nothing but a pole.



By the way, if you ever build one of these, or if you want to "heavy-up" the service to this one, you really ought to use a pair of transformers to step up the voltage for the 1000' haul. It's way cheaper than "throwing cubic copper" at the problem. You can kick it as high as 600V on existing wires (lots higher on pole line), but even kicking it to 480V has dramatic effect on voltage drop.

An example: Let's say, 1000' run 100A service, calculating on 80A@240V, you ran 500 kcmil AL feeder to keep voltage drop to 4.01%.

Now you decide you want 200A (calculating on 160A due to standard "derates") so you use 480V transformers, which steps up voltage and steps down current likewise (to 80A). With that existing 500 kcmil AL feeder, that voltage drop is now only 2.005%. That's great! LOL!

How far can we push it? Consider a 600A service. (calculated as 480A @ 240V). Let's pull out all the stops and use 600V transformers. Stepped up to 600V, we have 192A on those wires. What's our voltage drop? 3.85% down the distance.

Wow, that isn't bad at all.

If you're turning a thought to that, then take the time now to figure out what the needed transformers will be, and check Craigslist and Facebook marketplace regularly. They pop up from time to time.




There is no required electrical code for this rural installation.

Not likely. Try "It's easy to build around here without any pre-accident inspections."

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  • Thank you for your answer. I will have to retrofit a ground from utility shed but not pictured in the diagram is the possibility the greenhouse is only wired for 120V, so the third wire could be used as ground. The most important thing is the safety of humans, that in the event of a short/fault, electricity has a path of low resistance back to the transformer's "neutral". It is likely the utility co. will be providing a closer transformer in the next year or two. There are no subdivision, city, county, or state code requirements. Insurance companies and lawsuits might use their own rules.
    – Andrew
    Jan 29, 2022 at 20:21
  • Even if no code requirements locally, being up to code never hurt anybody(insurance and lawsuits), compared to not being up to code.
    – crip659
    Jan 29, 2022 at 21:34

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