Hot tub panel

[Frank P. Newman]

Inspected a house today that had a separate sub panel - found a) ground and neutral combined and b) a second ground rod driven and conncted to the ground/neutral of this subpanel. Is there something about hot tub wiring that makes either of these ok?

[Jae Williams]

Originally Posted by fnewman

Inspected a house today that had a separate sub panel - found a) ground and neutral combined and b) a second ground rod driven and conncted to the ground/neutral of this subpanel. Is there something about hot tub wiring that makes either of these ok?

In a sub-panel the grounds and neutrals must be on a separate terminal bus.

The neutral terminal cannot be bonded to the panel--it must "float".

The earth ground conductor must be attached to the ground terminal, the ground terminal must be bonded to the panel.

[Jeffrey R. Pope]

The "hot-tub" has nothing to do with anything. A remote panel can be wired that way if certain conditions are met.

[Speedy Petey]

Jae, Jeff is correct here. This can be quite compliant under certain circumstances, IF the panel is detached from the structure.

[Frank P. Newman]

Originally Posted by jpope

The "hot-tub" has nothing to do with anything. A remote panel can be wired that way if certain conditions are met.

OK-forgetting the "hot tub", what would the certain conditions be?

[Jeffrey R. Pope]

There must be no other metallic connection between the panels - such as metallic piping, conduit, fences, foundation steel, etc.

There should also be a disconnect for the remote panel, located in the service panel (or the panel feeding the remote panel).

[Frank P. Newman]

Originally Posted by jpope

There must be no other metallic connection between the panels - such as metallic piping, conduit, fences, foundation steel, etc.

There should also be a disconnect for the remote panel, located in the service panel (or the panel feeding the remote panel).

This panel is mounted on a vinyl/wood wall and fed with 2/C w/gnd, non-metallic sheathed cable from a dedicated breaker in the main panel, so based on the above, combining the neutral and ground and connecting a local ground rod would be ok? I've learned something new today - thanks !!

[Jeffrey R. Pope]

In many instances, the most difficult part (from the perspective of an HI) is verifying the absence of any additional metallic paths.

It sounds as if yours may be just fine. . .

[Frank P. Newman]

Yes, that can be difficult in some cases. I happen to know the contractor who built this particular house and am pretty familiar with the building practices in the area, so can be 99+% certain that no metallic conduit or other connection is involved. The exposed exterior conduit is all PVC as well.

It is interesting, because in the year or so I have been visiting this forum, I don't recall seeing this discussion before (usually the answer is always that 'subpanels require separate neutral and ground, etc.'). However, I would think this situation could easily exist in a majority of contenorary wood frame homes. Thanks again.

[Jeffrey R. Pope]

The exception only applies to remote (sub) panels that are not attached the the building where the service equipment is located. Whenever the panels are part of the same structure/building, the neutrals must not be grounded at any point, other than at the service equipment.

I believe this exception is being eliminated in the '08 NEC. . .

[Frank P. Newman]

Interesting - so if the panel (like this one) is mounted on the outside wall of the house the exception does not apply, but if on a fence 10' away surrounding the hot tub it would be ok? I guess that's what keeps it interesting and confuses the average installer!

After 40+ years in heavy industrial electrial engineering work, I am still trying to get my arms around the residential portions of the NEC. However, whatever changes come with the '08 code probably won't matter a lot out in the county around here as there is no AHJ!

Given all the above, I will probably put this installation in my report for follow-up but the 'qualified electrician' they are likely to call will say it is ok.

[Jeffrey R. Pope]

Originally Posted by fnewman

Interesting - if on a fence 10' away surrounding the hot tub it would be ok?

Not necessarily.

It's always been my position that a Home Inspector is well within their "rights" as a generalist to defer a remote panel installation that is not a four-wire feed, with isolated neutrals, because it can be difficult to determine if the installation is compliant.

If I cannot conclusively rule-out the potential for an "additional metallic path/connection," I will defer the installation for verification.

[Speedy Petey]

Originally Posted by fnewman

This panel is mounted on a vinyl/wood wall and fed with 2/C w/gnd, non-metallic sheathed cable from a dedicated breaker in the main panel, so based on the above, combining the neutral and ground and connecting a local ground rod would be ok?

Actually no, this is not ok.
The ground of a two-wire NM cable CANNOT be used as a grounding and a grounded conductor. The bare wire in NM cable is NOT meant to carry current.

One of the specific circumstances is that the grounded conductor MUST be insulate or be part of a Type SE cable, such as SEU.

[brian winkle]

It doesn't sound like a separate structure is involved here. If so, how does the NM get there? Not only is the NM not allowed to carry neutral current on it's bare grounding conductor like Petey said, it is also not allowed in a wet location.

[Greg Fretwell]

Defer it to an electrician who works on pools and spas. That is not usually the garden variety residential sparky