sub panel ground issue

[Don Hawley]

This is a 4 wire feed to a sub panel for a hot tub on a Deck. The grounds and neutrals are separated and the ground bar attached directly to the panel. So far so good, then there is a ground rod and wire attached to the neutral bus instead of the ground bar. I don't think this is correct but every thing else appears to have been professionally done. Is this correct or should the Ground wire be moved to the ground bus. Never mind the ground wire is black. 34886

[Jim Port]

Are you saying the black conductor goes to a ground rod?

The tub should not have a ground rod.

[Bill Kriegh]

I'm not sure I see anything professional here. The PVC male adapter needs a bushing. Grounding conductors don't appear to be connected to the enclosure. The neutrals appear to have a "grounding" conductor of some kind attached, which is a big no-no.

Whether the "looks like" ground rod wire (grounding electrode conductor) is required depends on certain things, but if the small panel is mounted on the same structure where the main disconnect is the GEC shouldn't be there. And, if required for some reason, can't be run through that big knockout hole without a clamp/bushing of some kind.

I would also be concerned about how the cable that enters from the back is connected to the enclosure.

Maybe the screws that hold the enclosure to the structure are OK.

[Gunnar Alquist]

Hi Bill,

Related/unrelated question here.

This is more in line with the current supplemental ground rod requirement. For the purpose of my question:

Assuming that the spa panel is attached to the home, that the GEC to the nearby rod is properly sized & connected, and that the EGC between that spa panel and the service equipment is properly sized & connected, would that meet the supplemental rod requirements of 250.53(A)2?

Correlated question:

Would the required rod at a detached building (again assuming correct sizing and connections) meet the supplemental rod requirements of 250.53(A)2?

Thanks

[Jim Robinson]

Using a four wire feed that was properly wired, what would the downside be of having a ground rod connected to the ground terminal bar?

[Bill Kriegh]

Hi Gunnar
The required grounding electrodes for an electrical service need to be connected at the service disconnect. Installing a second ground rod at a second panel location wouldn't meet the requirement. Also, in keeping with good practice the electrodes should be as close as possible to the main disconnect.

[Bill Kriegh]

The reason the grounding electrodes need to be as close as possible to the service is to keep high voltage surges from traveling to other areas to find a ground access.

Grounding electrodes are there to protect against surges related to lightning or possible supply problems, like a high voltage cable falling on the service voltage cables. The electrical system on a residence would work just fine without it.

The idea is to dump the high voltage to ground as close to the source as possible. You really don't want that voltage looking to take additional paths to get to ground as the stuff doesn't respect the insulation on the house wiring - for all practical purposes it doesn't even know it's there.

Other issues happen when there is a neutral failure between the house and utility supply, or another structure has neutral problems. Now the neutral current starts looking for another way to the source (transformer) and when it finds them it will use all it finds. That means the second ground rod location will be putting neutral current on the grounding conductor. Which way it's trying to go will depend on the failure involved.

I'm trying to put a whole book's worth of info in a few sentences here, but the whys are pretty complicated. Just winds up being one of those things where more isn't better, or even good.

[Gunnar Alquist]

The required grounding electrodes for an electrical service need to be connected at the service disconnect. Installing a second ground rod at a second panel location wouldn't meet the requirement. Also, in keeping with good practice the electrodes should be as close as possible to the main disconnect.

Thanks Bill. I had forgotten the close as possible part of the GEC.