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Consider the following scenario. A 240/120-V split-phase overhead service. The service conductors from the pole-mounted utility-owned transformer come overhead with a guy wire. They enter a weather head, and travel down in conduit, where they reach the meter, and continue and reach the soil level. Then they travel through underground conduit, reach a manhole, and then continue underground. They come across a 90-degree bend and reach the surface, then they continue and reach the service disconnect. Is it allowed by the Code to ground the neutral wire at the manhole? And, is it allowed to connect the supplemental ground rod directly to the neutral wire, instead of connecting it to the first rod? This is shown below, where the phase wires are omitted for simplicity.

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Figure 1. Image source: own.


Edit: Suppose there are actually two manholes, each with a ground rod, to comply with the minimum 1.8-meter distance between them (section 250.53(A)(3).) Also, I’ve clarified the meter, service disconnect and panel were attached to a wall of a house outside, perhaps in the backyard. And also that the ground rods under consideration are not those from the utility. Like this:

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Figure 2. Image source: own.

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  • @RobertChapin Sorry, I thought I’d be obvious the meter, service disconnect and panel were attached to a wall of a house outside, perhaps in the backyard. I think those details are irrelevant.
    – alejnavab
    Commented Dec 7, 2023 at 14:09
  • That's a huge assumption. I thought the question was about temporary service for new construction. Commented Dec 7, 2023 at 14:35
  • Can you ground the neutral (to dirt) elsewhere - evidently yes, as the power company ground it to dirt at the service pole. Is that dirt connection at the service pole part of the grounding system at my house that's bonded to copper ground? Nope. Does that dirt rod connection count as one of my copper grounding system dirt rod connections? Also nope.
    – Ecnerwal
    Commented Dec 7, 2023 at 14:58
  • @Ecnerwal Sorry again, I’ve also clarified the two ground rods under consideration are not those from the utility.
    – alejnavab
    Commented Dec 7, 2023 at 17:27
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    Gotcha. Maybe it could have been an, "I believe I can do this because, A, B, C. Am I reading this correctly?" type of question, then. The way it was worded seemed as if you were asking then answering all at once.
    – FreeMan
    Commented Dec 7, 2023 at 19:40

1 Answer 1

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I think yes, it is allowed, for both questions. For the first question, section 250.24(A)(1) of the 2020 NEC states that the service neutral wire must be be grounded anywhere between the load-end of the service conductors and the service disconnect, including those two locations, and wherever it’s done it must be accesible for inspection. So since a manhole is between those two and it’s accesible, then it’s permitted.

I know I should check with the AHJ (authority having jurisdiction) and maybe the PoCo (power company), but for this question let’s ignore it and only focus on the NEC.

My understanding of such NEC section is that the system grounding (grounding of the neutral wire) must be made only a) at the load-end of the service conductors, or b) at the meter socket enclosure (must check with utility company and AHJ first) or current transformer enclosure (for commercial and industrial installations), or c) at a wireway or auxiliary gutter between the service conductors and the service disconnect, or d) at the service disconnect enclosure wherever it is located (whether in an individual dedicated enclosure or in the main panelboard or in a meter-main combo); see figures 3–5.

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Figure 3. Image source: Minessota Electrical Association (p. 16).

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Figure 4. Image source: Minessota Electrical Association (p. 17).

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Figure 5. Image source: Mike Holt's Illustrated Guide to Understanding the National Electrical Code, 2020 NEC, volume 1 (p. 248).

And for the second question, section 250.53(A)(2) allows on item (1) to connect the supplemental rod directly to the neutral wire instead of to the first rod.


Sorry if I’ve already self-answered my question. I just want to be sure.

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