Separate ground rod at pool subpanel?

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cybertoad

Well-known member
Jan 30, 2019
53
California
I'm just curious how many others do or don't have a separate grounding rod installed at their pool equipment subpanel. Our pool was built last year and does not have a separate grounding rod, only the equipment ground running in the underground PVC conduit back to the main panel. Our inspector apparently did not require a separate grounding rod, because our pool passed.

The reason I am asking: From my reading on the Mike Holt website, any time a subpanel is installed detached from the main structure, it is considered a remote subpanel and the NEC apparently requires dedicated grounding rod(s) in addition to the equipment ground running back to the service entrance. This even includes panels that are mounted 12 inches away from the main structure on a separate post, as ours is, as the post is detached from the main structure and technically deemed a separate "structure."

I'm curious if these (well intentioned) code guys are "all wet" in terms of actual industry practice, or if my pool needs an upgrade.
 
CT,

Most residential pool sub-panels do not use a separate ground rod. The equipment pad is considered part of the main house assuming that is where the power is coming from.

Thanks,

Jim R.
 
NEC states there will be only one electrical ground point at the main panel. All subpanel grounds should be connected to the main panel and ground.

Multiple grounds can cause current imbalances.
 
CT,

What is your goal? Your pool passed the local code inspection and two people here have said it is ok as is... :scratch:

Why are you concerned and what advantage do you believe that a second ground rod will provide.

It is not like the grounding Police are going to raid your house in the middle of the night... :)

Thanks,

Jim R.
 
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Now that I've heard from some pool experts on the matter, I'll probably leave well enough alone. It was mostly just was just an academic curiosity on my part as to whether my pool, despite passing local inspection, actually is compliant with a strict interpretation of the current NEC, and whether or not some jurisdictions are requiring auxiliary electrodes. The only advantage an auxiliary ground would provide is redundancy in the event that the primary service grounding system becomes unknowingly compromised years down the road due to loose or corroded connections (rare but not impossible.) When it comes to electricity around water, I have a tendency to want to overthink safety, which is why I just ripped out a perfectly good 12 volt landscape transformer and replaced it with a pool-rated safety transformer to power my landscape lights around the pool, and why I'm going to add a GFCI breaker to our gas fired heater that currently doesn't have one.
 
To the OP: I gave the 2017 NEC a quick scan. While a separate ground rod is required for subpanels "in a remote building or structure", and structure is defined so helpfully as "that which is build or constructed", it's in my non-electrician mind a bit of a stretch to consider a sub-panel mounted on a post 12" from your house a "structure". Ultimately, what matters is what the local AHJ says, and the inspector, who signed off on it. (and that it's safe)

Out of curiosity, why was the sub-panel mounted on a post and not just mounted directly to the house?

ajw22 said:
NEC states there will be only one electrical ground point at the main panel. All subpanel grounds should be connected to the main panel and ground.
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One connection between neutral and ground at the main panel, but not one connection from the ground conductors to ground. The 2017 NEC requires that remote building or structure subpanels (outside of the main building) have their own grounding rod system. This is in addition to a ground wire running between the remote panel (and the remote ground rod), which connects to the main panel ground and main panel ground rod. The neutral at the remote sub-panel is not connected to ground at the remote sub-panel though, as the only location neutral can be connected to ground is at the main panel (since 2008 anyway, as earlier NEC editions allowed "re-grounding" the neutral). The only exception to this is a single branch circuit powering the remote building or structure, including a multi-wire branch circuit, that contains an equipment ground.
 
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