Article 408.37 refers you to Article 312.2(A) for requirements for mounting panels in damp or wet locations. Art. 312.2(A) requires that meter sockets, panelboards and such be mounted with a 1/4 inch air gap behind them. On many residential and some commercial projects I see these item recessed in the stucco or brick. Is this a violation of 312.2(A)?

We had this question a few years back, if I remember correctly.

Before I can respond let me ask, who is the power company?

There are three companies locally FP&L, FPU and Okafanokee. But this also involves the panelboard and other cabinets installed outside, this is the thing I am most interested in, not the utilities guidelines. I guess I mean to ask, does a panelboard (and possibly a disconnect) need to have a 1/4 inch air space behind it as required by Article 312.2(A).

I think the bottom line would be the manufacturer's instructions and the listing. If they say the panel was listed to be buried in the wall or the instructions say it can be mounted in the wall, it would be OK. Otherwise this is probably a violation.
In the case of a meter base I would also question the service conductors being "inside" the building. Is there 2" of concrete cover over that raceway?

My short answer is "no" and I will speak in general terms and avoid a huge discussion on meter sockets, and power company requirements.

The purpose for the 1/4" gap is mainly for the manufacturers of the electrical equipment - so that when they make the enclosures in the factory, they will automatically have the 1/4" gap in the rear (if the enclosure is mounted on a solid surface). Keep in mind here that the intent of the code is to prevent the rear of the enclosure from corrosion.

I have heard it argued by some that the purpose was to have "air" be able to flow behind the equipment thereby providing a means to "cool" the enclosure. This is not the intent.

If a contractor mounted the equipment in brick or some other surface and it was sufficiently sealed around the enclosure such that water could not enter behind the equipment at all, then I would say that the intent of the code is satisfied, and move on to the next inspection. I for one am guilty of violating this code. When I had my electrical contracting business, I would purposely silicone seal around every enclosure, after I mounted it to the building surface. Hence, no gap. However there was no way for water to penetrate behind the enclosure.

If anyone has documentation to the contrary, I would be interested in seeing it.

Lastly, here is what the handbook has to say:

handbook link



Bryan if you are reading this I will give you a call next week. I've been busy lately so I apologize for not calling.

In almost all cases, enclosures identified for use in wet locations are manufactured with the 1/4" gap with the use of cleats, domed recesses, or other effective means. I am referring to the little feet on the back of the enclosure that stand the enclosure of the surface it is mounted to.

There are many builders that will coat, finish, and paint the exterior wall at the service equipment location prior to the installation, however many do not.

I don't see the matter being all that critical...

I guess that was my main point. If the 1/4" language was not in the code, some of the manufacturers might no longer make the equipment with the factory offsets.

Yes it is a violation of 312.2. If the box is designed for surface mounting then it should be mounted on the surface, not partially inclosed by stucco, brick, or other material. As stated in 312.2 the purpose is to prevent moisture or water from entering the enclosure. If it is inclosed you have just increased the chances of moisture or water intrusion.

I just don't agree, I'm sorry. I think you make a huge leap with your last sentence.

The handbook clearly states that the 1/4 inch is to prevent corrosion at the rear of the enclosure. Whether the enclosure is surface mounted, partially enclosed in stucco or brick, the enclosure still has that 1/4" in the rear, and the enclosure doesn't change the way it is constructed, or how it opens and closes. The chances of moisture or water intrusion do not "increase."

I have been doing electrical for over 20 years. My experience has been that the only thing which tends to corrode (over many years) is always the BOTTOM of the enclosure.

This discussion has some interest to me.
Due to while I was at progress energy.
I was on the meter book committee at the time.
Some where in the panhandle area.
A contractor called on a issue that the meter can was mounted on a residential home. It was mounted on a block wall but had a brick veneer.
So meaning the meter can was recessed,flush with the brick veneer.
Our meter dept. turned down the installation. For no accessibility to the can. I can only guess now that the reason was no access to the sides of the meter can.
It was like 8 years ago.
There was a underground pvc stub out from the can.
So at the time there was not a issue with running the service conductors.
And of course the contractor stated that they have been doing it for years.

At that point in time I was concerned about the 1/4 inch air space so I was not in agreement with the contractor.

Knowing that the utility company did not adhere to the nec at the time.
But today looking at this discussion.

Would this type installation be considered in or out of the building.
Meaning the service conductors are under the brick veneer but on the surface of the concrete block.