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.

If you go into meter sockets with this post, please disregard everything I previously said. Power company requirements would preclude such installation recessed, in most cases. That is why I did not want to relate this discussion to meter sockets, just to NEC in general terms.

Chicken!
Okay change my post to the service disconnect that would be with a close nipple to the recessed meter can.Which would be recessed right beside it.

Nick,
Directly from you link "312.2 Damp and Wet Locations. This section addresses "damp and wet locations". The Code requires all equipment covered by this article to be "placed or equipped" so as to ensure water does not enter or collect within the enclosure. ADDITIONALLY, a minimum clearance from the mounting surface of 1/4 in. must be maintained to prevent corrosion of the enclosure."
If the enclosure that is designed for surface mounting is enclosed by stucco, brick, or other material, how does this not increase the chances of moisture intrusion? Does the installer ensure that the minimum 1/4" clearance on the top, sides, and bottom is maintained?
I started in the electrical trade in 1970, and the inspection side of the electrical industry in 1994 and I have seen numerous enclsures where corrision was not confined to the bottom area, granted that is the location that will confine the most moisture/corrision inducing material, but I still maintain that to enclose the equipment is a violation of 312.2

Joe,

I agree that we are talking about the section that you mention. I just don't happen to agree with a lot of the other things you are saying on this particular issue.

Using the same logic, I can ask conversely, "How DOES enclosing the sides and rear of the enclosure INCREASE the chance of water getting back there?" It doesn't. If someone has data to the contrary, I would be interested in seeing it.

If I silicone around the enclosure and the mounting surface, it still has the 1/4" clearance in the rear. It's built-in due to the manufactured offsets in the rear of the enclosure. Nothing changed. Additionally, the sides and top and the bottom do not require 1/4" clearance. Only the side that it is mounted on,

"and shall be mounted so there is at least 6-mm (¼-in.) airspace between the enclosure and the wall or other supporting surface..."

In fact, the equipment is rated NEMA 3R. If I place silicone around the enclosure where it is mounted on the wall, the equipment is still rated NEMA 3R. Nothing changes. I can argue that I made it even better. NEMA 3R is only designed to provide a DEGREE of protection against 45 degree angled rain. My way, I have 100% protection against any angle of rain. No water will get back there. The equipment would be very happy.

I do believe I would meet the intent of the section.

When panels are surface mounted than 312.2 applies and the 1/4" space is required. When panels are recessed inside the wall than 312.3 applies, and 312.2 no longer does.

I raised this question to the code panelist at the IAEI Southern Section meeting yesterday and Mark Ode, Jeff Fecteau, both of UL and Keith Lofland of IAEI stated that unless the panel is listed as a semi-flush panel then it would be a violation of 312.2(A).

We are talking about panels "and such" or so the post is entitled; equipment in a general sense. Yes if outdoor panels were specifically flush MOUNTED it would be a violation. Only problem with that is -- most outdoor panels are only surface mount. So they must be mounted to the surface using the rear of the panel. Adding silicone around the edge as I described would not violate the listing. Neither would placing trim around the panel. Neither would placing brick around the panel. Neither would placing stucco around the panel. The 1/4" is still present, and the panel is mounted via the rear of the enclosure, so there is no listing violation. So the panelists are correct for the question that was posed. The only problem is that the answer does not help to substantiate your position.

I refer you to my previous answer since the 1/4" gap would still exist under these circumstances:



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

Suffice it to say, if a panel listed for surface mounting located on the exterior of a building in the juridiction of my employment was not found mounted on the surface of the final exterior finish, excluding paint, it would fail the inspection. Nick at this point in time you and I will have to respectfully agree that we disagree.

Yes Joe, we can agree to disagree. But if you red-tagged me for putting silicone around the back of a weatherproof enclosure then I have to admit - I would call the building official!

I didn't say anything about the UL product listing. All I quoted was the code sections and how they apply.

I also find it hard to believe that a WP panel or meter socket that is made to be mounted in wet locations can't be recessed in the wall just like the regular panel. Is the enclosure metal and paint on a WP panel different?

I still think you run into a 110.3(B) problem. What do the installation diagrams show?

There is no listing violation if one installs using the back screwholes.

When I look at the SqD site I see two different numbers for surface and flush mount 3r "all in one" panels (just an example). Is the difference only in what cover you get or is there another difference? How are they labeled?

Maybe Jim Pauley can answer that. Anyone talking to him lately?

Can you post the links to what you are looking at?

Flush panel

http://www.schneider-electric.us/product...;countryCode=us

Surface panel

http://www.schneider-electric.us/product...;countryCode=us

Otherwise spec'ed the same.
Is the only difference the cover?
Does it come with different installation instructions?

It may not be an issue but I know a lot of things here have come down to what the manufacturer says in their paperwork.

I do not have a huge problem with these things being flush mounted except for the service entrance conductors traveling any significant distance in the wall, even if it does make a "neater" installation.

When you look at 408.37(A) (panelboards) or 240.32 (enclosures for overcurrent protection), they both specifically refer you to 312.2(A) not 312.3. 312.3 appears to be describing loadcenters that are flush mounted.