Proper mounting of NEMA 3R Box

[parallon]

Hello all. I am from New Mexico, USA. I just tried to get a final inspection for some electrical work done on a new steel building. I stuccoed the building and have 1-1/2" foam attached to the metal siding rather than MDF, with the stucco on top of that. Anyhow, I installed an 50A GE RV Panel directly to the metal siding before the stucco was installed, because I thought is might eliminate undue stress on the stucco when plugging and unplugging. Well, the inspector is stating that there needs to be space behind the box for circulation, in other words, it would need to be mounted on top of the stucco rather than imbedded within it. I contacted GE about the situation, and they informed me that unless the inspector can find anything in the NEC codes that specifies this requirement, they don't see why it can't be installed this way. Does anyone know what the correct answer is on this?

Here is the item in question: GE 50A RV Panel

GE RV Panel with 50 Amp RV Receptacle and 20 Amp GFCI Receptacle GE1LU502SSP - The Home Depot

Enhance any traditional indoor setting with the addition of this excellent GE Unmetered RV Outlet Box with GCFI Circuit Protected Receptacles. Easy to install.

www.homedepot.com

I would appreciate any and all information.

Thanks,

Mike

 

[retirede]

Not required if not specified in the installation instructions.

Ask the inspector to cite the section of code he claims you are violating.

 

[petersonra]

Not required if not specified in the installation instructions.

Ask the inspector to cite the section of code he claims you are violating.

312.2 Damp and Wet Locations. In damp or wet locations,
surface-type enclosures within the scope of this article shall be
placed or equipped so as to prevent moisture or water from
entering and accumulating within the cabinet or cutout box,
and shall be mounted so there is at least 6-mm (1∕4-in.) airspace
between the enclosure and the wall or other supporting
surface. Enclosures installed in wet locations shall be weatherproof.
For enclosures in wet locations, raceways or cables entering
above the level of uninsulated live parts shall use fittings
listed for wet locations.
Exception: Nonmetallic enclosures shall be permitted to be installed
without the airspace on a concrete, masonry, tile, or similar surface.
Informational Note: For protection against corrosion, see 300.6.

I don't see where it cannot be inset but it does seem to require air space. Maybe a nut between the box and the siding?

 

[wwhitney]

So because the enclosure has a door, it's a "cabinet or cutout box" and subject to 312.2, rather than an "outlet or device box," subject to 314.15?

Cheers, Wayne

 

[parallon]

I don't see where it cannot be inset but it does seem to require air space. Maybe a nut between the box and the siding?

@petersonora
Reading that, I agree. There is actually a bigger gap than that behind the box, although it can't be seen due to the stucco surrounding it. The panels of the siding underneath are ~1" high themselves, and the box is resting between 2 of them. And either way, the box itself has 1/4" raised portions at the mounting spots (see attachment).

@wwhitney
Thank you for that clarification.

@retirede
Thank you for the info. Will do...



Mike

 

[retirede]

I don't see where it cannot be inset but it does seem to require air space. Maybe a nut between the box and the siding?

I had forgotten about that. The mounting provisions on 3R boxes usually provide the spacing.
It would seem that the spacing is there in this case, but no way to prove it.

From a practical standpoint, it’s not really needed in this case, but the exception does not seem to apply?

 

[jap]

The rule is for equipment being installed in damp or wet locations.

What they are regarding as "air space" behind the unit is to let any moisture or water to get out from behind it to protect it from corrosion.

Not for cooling purposes of any sort.

Notice the exception for non metallic units not needing this gap for that reason.
A non metallic unit is corrosion resistant already.

In your scenario, water or moisture would have to get in behind the stucco then run behind the unit to get trapped and cause a problem.

In my mind , you're actually helping what the code is trying to prevent, not hindering it.

JAP>

 

[parallon]

The rule is for equipment being installed in damp or wet locations.

What they are regarding as "air space" behind the unit is to let any moisture or water to get out from behind it to protect it from corrosion.

Not for cooling purposes of any sort.

Notice the exception for non metallic units not needing this gap for that reason.
A non metallic unit is corrosion resistant already.

In your scenario, water or moisture would have to get in behind the stucco then run behind the unit to get trapped and cause a problem.

In my mind , you're actually helping what the code is trying to prevent, not hindering it.

JAP>

Thank you so much for your answer. I completely agree. Still haven't requested a reinspection, so we will see, now that I am armed with all this information.

Mike

 

[busman]

You should be able to see the stand-offs from inside the enclosure. I agree this would to prove the airspace though. Maybe you could remove a screw to show from the inside?

Mark