patching holes in panels

[thetacon]

In residential construction the panel cans are prepunched with 1/2" ko's everywhere. When it is reqiuired to punch a large hole that does not line up with a factory hole you end up with unintended ko's getting partially punched out leaving holes in the can that cannot be filled with ko seals. what i have found to be the cleanest way to deal with this is I screw on a 4sq cover with 4 -8/32 tapped into the can at the location i need to punch my hole . Then i punch through the can and the cover leaving a very clean solid can and installation. I could use very large reducing washers but it never in my opinion creates as solid installation.

Is a 4sq cover required to be listed for this installation, and is this a code compliant installation

thanks for your time
geoff

 

[480sparky]

I'd say a 4square cover isn't listed for that use, but I've seen it done many times, and it passes.

This is why I say no panels should have factory KOs in them. I hate Mickey-Mouse KOs.

 

[jeremysterling]

When the "4 square blank" becomes a piece of "scrap sheet metal", i.e. when you name it such, it has therefore become "suitable" for adaptation as a "hub" for your panel. In other words, common sense prevails.

 

[thetacon]

thanks for the replies. I agree that this is more a matter of common sense rather than the listing of a product. This all came about because the other electrician on the job felt that this was a code violation, siting the listing issue.

This issue is no big deal at all. What it did point out for me though is that I need to gain a better grasp on how to determine what the listing is on a product.. do you have any suggestion on the best method for doing this, not just for this situation but any product that may come up?

thanks

 

[iwire]

I also use 4" square blanks or sometimes metal from left over tough ect.

When the "4 square blank" becomes a piece of "scrap sheet metal", i.e. when you name it such, it has therefore become "suitable" for adaptation as a "hub" for your panel. In other words, common sense prevails.

That is how I see it as well, IMO if you do it 'neat and workmanlike' :wink: no one should have a problem with it. :smile:

 

[LarryFine]

This all came about because the other electrician on the job felt that this was a code violation, siting the listing issue.

And their recommendation for the problem is ... ?

 

[Pierre C Belarge]

Here is the issue I would have with this installation.

1. For nonmetallic raceways, I have no issue at all.


2. For metallic raceways, I have concerns for bonding to facilitate the effective ground fault current path.
2a. If the installer uses tapping type screws, I have concerns that the connection of the plate to the box may not be able to carry fault current. We discussed this at a UL class presented by the Under Writers, and it would not be considered sufficient as the fault current path.
If, instead of using tapping type screws and one was to use screws and nuts, it then would be considered sufficient to carry fault current.

 

[brian john]

This is one of those things that is pretty common place and is a better solution than the option in my opinion, a sloppy 2" hole surround by one or more 1/2 of a 1/2" KOs or reducing washers.

 

[iwire]

2. For metallic raceways, I have concerns for bonding to facilitate the effective ground fault current path.
2a. If the installer uses tapping type screws, I have concerns that the connection of the plate to the box may not be able to carry fault current.

Generally I use 1/2" x 1/4" x 20 Hex head bolts with 1/4" x 20 nuts.

I really have little faith in field taped holes into the thin metal of cabinets.

 

[don_resqcapt19]

Here is the issue I would have with this installation.

1. For nonmetallic raceways, I have no issue at all.


2. For metallic raceways, I have concerns for bonding to facilitate the effective ground fault current path.
2a. If the installer uses tapping type screws, I have concerns that the connection of the plate to the box may not be able to carry fault current. We discussed this at a UL class presented by the Under Writers, and it would not be considered sufficient as the fault current path.
If, instead of using tapping type screws and one was to use screws and nuts, it then would be considered sufficient to carry fault current.

Given that UL says standard reducing washers are suitable for carrying fault current, I would have no issue with any type of screw that was used to hold the plate to the panel.

 

[brian john]

I have seen electricians use 2-1900 plates as homemade reducing washers. Not sure why they did not just use one and bolt it?

 

[chris kennedy]

This is why I say no panels should have factory KOs in them.

Agreed, they are hardly ever where I need them so whats the point?

 

[480sparky]

So if 4square covers can be used as blunder plugs, can sheet metal be used for breakers that have been removed as well?

 

[Pierre C Belarge]

Given that UL says standard reducing washers are suitable for carrying fault current, I would have no issue with any type of screw that was used to hold the plate to the panel.

Don
I know you do not have the greatest of respect for UL, and I can understand it. I still base a lot of my understanding of topics based on conversation or documents from them, as they have a ton more experience and access to info than I do.

That said, the difference between the reducing washers and the field installed plates is:
The reducing washers have been tested, so they are a known quantity.
The plates are field installed and have not been tested, hence they are an unknown quantity.

Not that I do not respect your knowledge, I do, I just try my best to understand and many times have to defer to those who know more than I do.

 

[jim dungar]

So if 4square covers can be used as blunder plugs, can sheet metal be used for breakers that have been removed as well?

I think it should be the same gage steel as the panel.

 

[cpal]

In residential construction the panel cans are prepunched with 1/2" ko's everywhere. When it is reqiuired to punch a large hole that does not line up with a factory hole geoff

just curious.
why couldn't offset nipples or fittings be used?

 

[cpal]

So if 4square covers can be used as blunder plugs, can sheet metal be used for breakers that have been removed as well?

408.7 Unused Openings.
Unused openings for circuit breakers and switches shall be closed using identified closures, or other approved means that provide protection substantially equivalent to the wall of the enclosure.

If the AHJ will approve it its good to go

 

[ibew441dc]

4 square is a great filler.......

4 square is a great filler.......

Is a 4sq cover required to be listed for this installation, and is this a code compliant installation

110.12(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 (? in.) from the outer surface of the enclosure.

IMO a 4s blank is stronger than the material used for many cabinets.....that being said, it is perfectly legal, and base my opinion on the rule as stated in 110.12(A).

As Pierre C Belarge pointed out, attention must be made as to how the hole filler is attached to the enclosure.

 

[e57]

just curious.
why couldn't offset nipples or fittings be used?

Ughhhh....

 

[brian john]

Don
I know you do not have the greatest of respect for UL, and I can understand it. I still base a lot of my understanding of topics based on conversation or documents from them, as they have a ton more experience and access to info than I do.

That said, the difference between the reducing washers and the field installed plates is:
The reducing washers have been tested, so they are a known quantity.
The plates are field installed and have not been tested, hence they are an unknown quantity.

Not that I do not respect your knowledge, I do, I just try my best to understand and many times have to defer to those who know more than I do.

BUT Pierre this goes hand in hand with the dumbification of our trade. Common sense and experience SHOULD go a long way, but it has no bearing anymore. I guran-fricking-tee you that a 1900 plate WITH TAPPETS (I use 1/4-20s) equals or exceeds reducing washers, the flimsy sometime impossible to seat junk.