open mounting hole in panel

[John Dirks Jr]

This panel was mounted using screws through the side into studs. The there are two open mounting holes in the back of the panel. They are about 3/4" in diameter. i know you would call an open knockout, but would you also call these open mounting holes because of their size?

Image Insert:

92.59 KB

[Sodapop]

NEC 2008 11012(A) Unused openings

Unused openings, other than those intended for the operation of equipment, those intended for mounting purposes, or those permitted as part of the design for listed equipment, shall be closed to afford protection substantially equivalent to the wall of the equipment. ....

(Italicized indicates change from 2005 NEC)

These openings are not required to be covered. Usually the back of the panel is up against a wall. From the photo I take the opening to have a space behind the panel and not flush to a wall. Mounting the panel through the side screw holes into the stud is common practice in residential. You would typically use those holes when mounting the panel to a basement wall.

Mounting of panels must also meet NEC 2008 314.23 Supports

[John Dirks Jr]

Thanks Sodapop,

I will still be writing up the panel and calling for an electrician for other reasons. There is no labeling and a number of unmarked white hots. Since the electrician will be on site I will suggest that they cover the holes .

Its just makes sense to do it. An item does not have to be against code to make sense, nor does it have to be against code to be commented on in an inspection report.

That's my opinion anyway.

[Neal Lewis]

So what is used to cover the holes? I wouldn't think the manufacturer makes anything to plug the holes.

[Jim Katen]

Originally posted by AHI

This panel was mounted using screws through the side into studs. The there are two open mounting holes in the back of the panel. They are about 3/4" in diameter. i know you would call an open knockout, but would you also call these open mounting holes because of their size?

There's no need to cap these openings. Sodapop gave the correct reference.

- Jim Katen, Oregon

[Eric B]

John,

Look at it this way, there was no knock out there to begin with. It's an intended opening.

[Brian G]

Black-letter code aside, I agree with John. What's the difference between an intended 3/4" hole in an enclosure and an unintended 3/4' hole in an enclosure, where safety is concerned? Zero. Nada. If there's a reason to close off one, there's a reason to close off the other. With what, in this case, I'm not sure.

Why does a panel need a big 'ole 3/4" mounting hole to begin with?

Brian G.

A Hole Isn't a Hole If It's Intended? [:-boggled

[Jim Katen]

Originally posted by Brian G

[navy]. . . Why does a panel need a big 'ole 3/4" mounting hole to begin with?

Call Underwriter's Laboratories and ask them.

Tell us what they say.

- Jim Katen, Oregon

[Brian G]

Originally posted by Jim Katen

Call Underwriter's Laboratories and ask them.

Would that be a UL thing? I would think the manufacturers make all the decisions about mounting holes (where, how many, how big, etc.).

Brian G.

5/8 Lag Screws Seem Excessive []

[Jim Katen]

Originally posted by Brian G

Originally posted by Jim Katen

Call Underwriter's Laboratories and ask them.

[navy]Would that be a UL thing? I would think the manufacturers make all the decisions about mounting holes (where, how many, how big, etc.).

They do make the decision. Then they send it to UL for testing. If it meets UL's testing and product standard requirements, then it gets listed.

- Jim Katen, Oregon