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4" sq. mounting revisited #90076 10/29/04 05:32 PM
Joined: Jan 2004
Posts: 1,507
G
George Little Offline OP
Member
It really bothered me about those small holes in a 4" square box that are sometimes used for mounting the box so I checked with NEMA and UL and this is what they came back with:
Quote
I checked with an Industry expert and he informed me that those holes are not for the mounting a box to the wooden 2x4. It will place the nail to close to the edge of the top edge of the 2x4. Mounting of the box this way could compromise the support of the box by allowing the nail to split of the edge of the wood.

These holes were used with a special bracket intended to secure the box to a lathe and plaster wall. The U shaped bracket would be secured to the side of the box by screws through the bottom of the U. One of the legs would be over the top and the other would be under the back side of the lathe. The appropriate size mud ring would be used depending on the thickness of the plaster.

No one makes or uses this type of bracket now. But the holes are still put in the boxes.
So there you have it.

[This message has been edited by George Little (edited 10-29-2004).]


George Little
2017 / 2014 NEC & Related Books and Study Guides
Re: 4" sq. mounting revisited #90077 10/29/04 05:40 PM
Joined: Jan 2003
Posts: 4,391
I
iwire Offline
Moderator
George I still have a problem. [Linked Image]

Quote
I checked with an Industry expert and he informed me that those holes are not for the mounting a box to the wooden 2x4. It will place the nail to close to the edge of the top edge of the 2x4. Mounting of the box this way could compromise the support of the box by allowing the nail to split of the edge of the wood.

I have not been on a job with wood studs in a long time.

I work on metal stud jobs, they do not split. [Linked Image]


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: 4" sq. mounting revisited #90078 10/29/04 06:20 PM
Joined: Apr 2002
Posts: 7,211
HotLine1 Offline
Member
Bob:
Yes, wood studs are becoming a rarity in comm work, and some resi is going steel also.

As to the holes......that was a decent explanation, and I've been around a while, & can't say I ever came across that clamp in any old resi with lathe & plaster walls/ceilings. Usually it was/is old black steel gems, ears turned back & 1/2" wood screws into the lathe. Or really old pancakes with a gas pipe hickey ane at least four BX's.

John


John
Re: 4" sq. mounting revisited #90079 10/29/04 06:28 PM
Joined: Jan 2004
Posts: 1,507
G
George Little Offline OP
Member
The discussion revolved around what are those holes really designed for? The answer was, (and I paraphrase) to install a bracket for supporting the box. Now if you are able to satisfy the supporting of a box using these holes, go for it. I was merely solving the mystery. I for one would not write a violation if an electrician used these holes to mount the box in a metal stud installation as long as it didn't interfere with fill or have any sharp edges. I would also look for a leg behind the box to provide rigidity due to the flexibility of the metal stud.On wooden studs I now understand that this would be a violation and would question the installation for the reason already stated.


George Little
Re: 4" sq. mounting revisited #90080 10/29/04 06:31 PM
Joined: Jan 2003
Posts: 4,391
I
iwire Offline
Moderator
George thanks for the info. [Linked Image]

I was just having some fun, do not take me to serious. [Linked Image]


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: 4" sq. mounting revisited #90081 10/29/04 08:51 PM
Joined: Jan 2004
Posts: 1,507
G
George Little Offline OP
Member
Bob- I've been an inspector for 20 years, taught code classes for ten years for Michigan State University concurrently. It would be pretty hard to get my goat [Linked Image]


George Little
Re: 4" sq. mounting revisited #90082 10/30/04 12:24 AM
Joined: Jun 2003
Posts: 1,143
D
DougW Offline
Member
I had to install a 1900 (4" sq) box the other day, and the only I had in my truck had a pre-formed sheet metal bracket for attaching to the face of a stud. Guess where it was secured to the box?


Yep... those two little holes.

So, I suppose the next question is.... do we "field expediaent", and drill the side of the box to make a hole at the proper depth?

Re: 4" sq. mounting revisited #90083 10/30/04 10:50 AM
Joined: May 2004
Posts: 697
D
Dave55 Offline
Member
I don't like deep bracket boxes, I feel like they're flimsy. If I want a deeper box I use a deep 4 X 4 and mount it onto the wood stud by drilling 3 or 4 holes and using deck screws. I'll also usually knock out a 1/2" knockout and screw a fender washer in it's place.

There, I've confessed. I feel SO much better. I don't know if it's code compliant, but you'd have a hard time pulling it off with a crow bar.

Dave

P.S. I also mount my receptacles horizontally, so the deck screws aren't close to live screws.

Re: 4" sq. mounting revisited #90084 10/30/04 02:29 PM
Joined: Dec 2003
Posts: 886
H
hbiss Offline
Member
... I don't like deep bracket boxes, I feel like they're flimsy.

I have never seen an unbracketed square box mounted to the side of a stud- at least by a professional. I can't see what you are after by thinking the bracket is flimsy. With wood studs no way are they going to move and with metal studs, well, nothing is going to make any difference anyway except far side and back supports.

One reason to use bracket boxes with wood studs that are sometimes twisted is that you can bend the box in or out to keep it parallel to the surface of the sheetrock. Mount a plain box as you do and you would bend the box all up trying to do this, or you could use shims. [Linked Image]

-Hal

Re: 4" sq. mounting revisited #90085 10/30/04 04:08 PM
Joined: Jan 2002
Posts: 1,457
E
Electricmanscott Offline
Member
Dave55, what are you suporting with that box? [Linked Image]

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