Panel over panel

[ryan_618]

I had the Chief Building Official of a nearby city call me today to get an answer on an NEC question. They have an old panel mounted flush inside a masonry wall. They intend to remove the guts out of it and mount a new panel over the top of the existing one. The new panel would completely conceal the old one. The old panel has a few conductors that run directly through the old panel --no splices, taps, twists, turns, etc... He was wondering if he could justify the old "box" as a raceway, since there are no splices. Your thoughts please...

EDIT: Keep in mind that I think it is a bunch of nonsense also, but I am intersted about the legallities of it, as per the NEC. OOPS! Can someone move this to the NEC forum please? :roll:
(Done. CEB)

[ September 05, 2003, 11:43 AM: Message edited by: charlie b ]

 

[iceman2610]

Re: Panel over panel

ryan_618, This is a very unusual installation request. I have found in my past expierence, the NEC leaves much of its finner points to the AHJ to decipher. I am an electrician, but my personal response to this would be NO. NEC intends for all raceways, fittings, and boxes to be servicable after the installation. The installation you are describing, would make the origional panel box a junction box, or a pull box(if no junctions exist). It would be no different than burring a LB inside the wall.

I would suggest extending the panel box outward and adding a cover so the new panel box could be mounted beside it. This would allow access to the box in question and be consistant with the code requirements of NEC section 314.29.

 

[a.wayne3@verizon.net]

Re: Panel over panel

So what you are saying is that they want to free air the conductors from the existing panel through the openings in the back of the new panel??????

 

[george t. everett]

Re: Panel over panel

Sounds like a violation to me.

 

[ryan_618]

Re: Panel over panel

Originally posted by a.wayne3@verizon.net:
So what you are saying is that they want to free air the conductors from the existing panel through the openings in the back of the new panel??????

No. The old panel is being removed, with the exception of the can (enclosure). The existing conductors in the can will remain. They come into the can in EMT and leave the can in EMT, without splice. The new cover will render them innaccessible. They AHJ wants to call the old can a raceway (don't ask me why?) The biggest question is: As per the definition of "raceway" is this installation legal?

 

[gregory]

Re: Panel over panel

Ryan
I go with the Iceman on this issue. 314.29 covers this installation. If you have noticed the large 1/2 moon cutouts on fluorescent strip lighting fixtures, the reason is to make the wiring in the boxes above the fixture accessable without removing the fixture. the same applies for putting a panel over a panel. it must be accessable.

 

[ryan_618]

Re: Panel over panel

Gregory: Thanks for your response. The difference between the strip light you speak of is the splice inside box behind the strip light. I don't want to sound like I condone this installation because I DO NOT, but take a look at the definition of raceway:
Raceway. An enclosed channel of metal or nonmetallic materials designed expressly for holding wires, cables, or busbars, with additional functions as permitted in this Code. Raceways include, but are not limited to, rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, liquidtight flexible conduit, flexible metallic tubing, flexible metal conduit, electrical nonmetallic tubing, electrical metallic tubing, underfloor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface raceways, wireways, and busways.

I agree it's a stretch...but what about "designed for holding wires, busbars, etc...

 

[Guest]

Re: Panel over panel

Can't you just use the Binford 9000 swing-away subpanel? That's what Tim the Toolman Taylor would do

Or, cut some 1/2 moons in the back of the new subpanel?

../Wayne

I hope you appreciate some humor here.

 

[russellroberts]

Re: Panel over panel

If the old box has conductors running through it ,wouldn't it have to be considered a pull box?

Russell

 

[gregory]

Re: Panel over panel

Ryan
314.29 BOXES and Conduit Bodies to Be Accessible.
Boxes and conduit bodies shall be installed so that the wiring contained in them can be rendered accessible without removing any part of the building.
314.29 requires boxes to be accessable. when you remove the guts from the existing fuse box it becomes a pull or junction BOX. Box is the key word. I do not think that this box is a raceway.

 

[big john]

Re: Panel over panel

At first, I was going to support the idea of simply mounting the new box over the old:
How would it be any different than a piece of rigid underneith two inches of concrete? It's just as inaccessable and serves the same function in my eyes.

However, the main difference is that in order to fix a fault in a piece of rigid under two inches of concrete all you have to disrupt is the concrete. In this case, you'd have to shut down and probably completely dissassemble the new panel entirely. Simply from the standpoint of possible future maintanence I wouldn't do it.

What would be the problem with cutting the old cables, putting a vertical trough next to new panel and splicing the old cables into that?

-John

 

[big john]

Re: Panel over panel

AND:
I may be preaching to the choir, but it just occured to me why the code is worded to specifically include boxes as in this case:
It may not have been a pull box when it was designed, but if anyone ever wants to fish a new circuit into one of those conduits, there's a good chance it could be a pullbox in the future. A pullbox that you can't pull from. Beautilous!
-John

 

[ryan_618]

Re: Panel over panel

Big John: Thanks for your reply. My answer to the question was very similiar to your own. I agree with your code interpretation (as well as the others who have posted), but I wanted to start this thread to initiate some thoughts on interpretation. Some of the strange questions we get asked... :roll:

[ September 06, 2003, 12:30 AM: Message edited by: ryan_618 ]

 

[Guest]

Re: Panel over panel

Can you post a picture of the box? A picture is worth 1000 words.

../Wayne

 

[pierre]

Re: Panel over panel

Ryan_618
From Merriam-Websters Dictionary

Convolution
3: a complication of intricacy of form, design, or structure.

The enclosure that was installed for the panel was, designed, listed, and installed for the purpose of enclosing a panel.
Now for convenience, someone wants to 'convolute' the process to make it easy for their own purpose.

I would politely tell the person(s) that the installation as they want to perform is not acceptable/permitted.

Pierre

 

[websparky]

Re: Panel over panel

Hi Ryan,

In a similar situation, the electrician covered the existing can in the wall with the new can but only covered 2/3 of it. The remaining 1/3 was covered with a custom made sheet metal cover which made the conductors accessible for future work if needed.

 

[jimb]

Re: Panel over panel

Although I'm sure they have their reasons for wanting to place a can over a can, it really seems like a half-way method for doing the job. I agree with all the others that the hidden enclosure would be a pull box and should be accessible. If for some reason it were absolutely impossible to install a trough or wireway maybe a variance could be granted but it's hard for me to believe that it would be impossible.

If, however, they INSIST upon calling it a "raceway" perhaps you could ask them if they will be able to comply with 310.15(B)(2)

Jim