Steel elecrical box/cover holes

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mnmaint

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I work in apartment maintenance. I have a few surface mounted square electrical boxes with covers. The covers attach to the box using 2 of the 4 holes. This leaves 2 holes open. My boss wants the empty holes plugged with a self tapping screw for safety reasons. He thinks someone will stick a wire in the hole an be electrocuted.
My question is, does code require the unused holes to be plugged?
I have attached a pic.
 

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Usually those holes need to be punched out so if you punched them and didn't use them then I believe they may have to be filled. Just take a nut and bolt and that will fill the hole. To be honest I am not certain what the nEC says on this.
 
I've never seen these holes with a knock-out in them. I've also never seen them filled later with a screw. The chances of someone poking a wire or nail or screw into that hole, finding a hot wire exposed or actually piercing the insulation and getting a shock without shorting the hot to ground in the hole is so much lower than if they just poked something into a receptacle that it seems pretty ridiculous to me to want them filled.
 
@mnmaint

Well, if those holes are designed as part of the mounting and securing (even if its the cover) then they do not have to be filled. Others may agree to disagree but it appears to me that Section 110.12(A) covers these openings. What's next....filling weep holes. (oh let's not go there).

With that said....if the man who is paying your salary wants it plugged...then I would plug them and do it with a smile. Just my thoughts on it:thumbsup:
 
I believe that a general purpose enclosure (e.g. UL Type 1) can have openings in it, as long as a 1/8" dia 'test probe' is excluded.
 
NEMA 250 Standard on Openings is covered but only for those enclosures that are desired to actually have the ratings on them like NEMA 1, 2, 3, Etc.


Below is just a sample of some of the test requirements for all openings.
3.6 OPENINGS
Openings provided in an enclosure shall comply with the tests for the enclosure type with the openings
unfilled except that openings in accordance with 3.6.1, if provided in the test enclosure, shall be filled to
maintain the environmental integrity of the enclosure.

Protected against access to
hazardous parts with a finger or wire


Non-Vented Live Parts
<102mm an access probe
of 3.2 mm will not penetrate

 
Dennis Alwon said:
Usually those holes need to be punched out so if you punched them and didn't use them then I believe they may have to be filled.
Click to expand...

I only get the ones with KOs in them sometimes. Normally the ones I get have all four holes open and I would never even consider that they need to be closed.



110.12 Mechanical Execution of Work. Electrical equipment
shall be installed in a neat and workmanlike manner.

(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. Where metallic
plugs or plates are used with nonmetallic enclosures,
they shall be recessed at least 6 mm (1?4 in.) from the outer
surface of the enclosure.
Click to expand...
 
mnmaint said:
My boss wants the empty holes plugged with a self tapping screw for safety reasons.
Click to expand...

A self-tapping screw may do more damage than just leaving things alone. The drill point can damage wire insulation. A stretch, but so is the thought of those holes posing any type of hazard. What does he have to say about the small holes that 1900 boxes sometimes have in their sides? Or the open corners in stamped/welded boxes? Are you supposed to weld those up? :)


SceneryDriver
 
MasterTheNEC said:
Are you actually referring to a NEMA Type 1 Enclosure versus a UL Type 1 Enclosure.
Click to expand...

For all intents these two ratings are equal.
Neither requires a enclosure to have absolutely no openings, as evidenced by the number of items with ventilation openings.
 
I've got a question,
what does he want you to do about the 2 small holes on the edges of that 4" square box?( the holes that are provided for attachment to plaster wall wires) at least I think that's what they were used for back in the day.
 
mopowr steve said:
I've got a question,
what does he want you to do about the 2 small holes on the edges of that 4" square box?( the holes that are provided for attachment to plaster wall wires) at least I think that's what they were used for back in the day.
Click to expand...

Actually, they're still for that, just like the two small holes on the side of metal wallcases. That tapping tool that Klein makes... you run the 8-24 tap (IIRC) through those holes, and you can screw the ears from a wallcase to the side of a 1900 (4" sq.) or the side of a wallcase and attach it to the face of a stud. Works great for stabilizing the free side of a gang of wallcases or for mounting 1900 boxes to studs.
 
PetrosA said:
I've never seen these holes with a knock-out in them.
Click to expand...

Here is one with the holes closed

36601851.jpg
 
Dennis Alwon said:
Here is one with the holes closed

36601851.jpg
Click to expand...

Interesting. Maybe it's a local manufacturer? I've never seen anything like that around here. It's even hard to find 4" sq. covers with raised corners like that here. Nobody likes hooking up ground wires to devices in PA I guess :)

Edit to add: The other difference I see is that that plate only has single screws for the receptacles. You can't get them here either.
 
PetrosA said:
Interesting. Maybe it's a local manufacturer? I've never seen anything like that around here. It's even hard to find 4" sq. covers with raised corners like that here. Nobody likes hooking up ground wires to devices in PA I guess :)

Edit to add: The other difference I see is that that plate only has single screws for the receptacles. You can't get them here either.
Click to expand...


Probably an older pic-- I am not in the field much so they may not make these anymore-- IDK. I just remember knocking out the small holes
 
Hey guys, since we are talking about these raised covers where the devices are mounted with small screws & nuts I have a question. Are there any easy ways to secure the small screws & nuts? I keep dropping one or the other. And, you might think that Raco would at least make the screw a Phillip's head instead of just a strait slotted screw.
 
Michael15956 said:
Hey guys, since we are talking about these raised covers where the devices are mounted with small screws & nuts I have a question. Are there any easy ways to secure the small screws & nuts? I keep dropping one or the other. And, you might think that Raco would at least make the screw a Phillip's head instead of just a strait slotted screw.
Click to expand...




I pull the longer 6-32s out of the device and reuse those with the nuts. The longer screws with their tapered end make putting the nut on fast and easy.
 
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