Properly Plugging Unused Knockouts

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Lake Country Sparky

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Semi Retired. Industrial Maintenance - Electrical, HVAC etc
Hey guys - noob here - first thread. Did a search and didn't find what I was seeking. What is the NEC compliant method for plugging an unused knockout hole where a conduit connector used to be? I see different types - the pop in friction fit, and the mechanical fastener fit with a screw or wing nut. Does the Code call for any particular type? I'm assuming an outdoor panel would require a more substantial knockout plug than an indoor panel in a dry location.

Anyway, thanks for answering by dumb question. :cool:
 
Anything that keeps a finger out is probably OK. When I'm out of KO seals, I'll use two fender washers with a 1/4" bolt and nut. In real emergencies, I've used a couple of layers of foil duct tape, although I doubt the code compliance of that.
 
Hoffman makes a similar plug to the Saginaw, also available in SS. I kept a good assortment of both in my work van, for NEMA 4 and 4X applications. T&B makes a plastic snap in KO plug I would use on NM enclosures, perhaps a bit of glue as well
For other KOS, the push in type or 3 piece are fine. The KO plug has to be rated for the environment.
 
110.12(A) requires that the closure be " substantially equivalent to the wall of the equipment ". While I have used the push-in KO closers, I don't see how they meet that requirement.
Often I have used a pair of fender washers and a nut and a bolt if I did not have an actual hole closer. Have also bolted a cover for a 4" square box over larger openings.
 
don_resqcapt19 said:
110.12(A) requires that the closure be " substantially equivalent to the wall of the equipment ". While I have used the push-in KO closers, I don't see how they meet that requirement.
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My theory is that the box could be as thin as the filler is. :sneaky:
 
Lake Country Sparky said:
Hey guys - noob here - first thread. Did a search and didn't find what I was seeking. What is the NEC compliant method for plugging an unused knockout hole where a conduit connector used to be? I see different types - the pop in friction fit, and the mechanical fastener fit with a screw or wing nut. Does the Code call for any particular type? I'm assuming an outdoor panel would require a more substantial knockout plug than an indoor panel in a dry location.

Anyway, thanks for answering by dumb question. :cool:
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110.12(A) "...shall be closed to afford protection substantially equivalent to the wall of the equipment." I would say that leaves it up to you. I like what Coppersmith uses when he is out of KO seals. Of course I always prefer the two piece screw type.
 
I have use box covers bolted on as well especially when you knock out the knock out and the whole thing comes out so know your oversized. Put a cover on it and punch it out
 
Jason Tilford said:
110.12(A) "...shall be closed to afford protection substantially equivalent to the wall of the equipment." I would say that leaves it up to you. I like what Coppersmith uses when he is out of KO seals. Of course I always prefer the two piece screw type.
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Thanks Jason! That Code citation tells me what I need to know.

Also appreciate all the tips guys! I've been out of the field in an office environment so long I've regressed back to apprentice. I need all the help I can get. :)
 
I'd say anything that satisfies the code referenced above. PLUS, if you are above the bus you have to satisfy the requirement for keeping it watertight. Can't remember the code section right off the top of my head.
 
Chamuit said:
I'd say anything that satisfies the code referenced above. PLUS, if you are above the bus you have to satisfy the requirement for keeping it watertight. Can't remember the code section right off the top of my head.
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I think the reference already given 110.12 "substantially equivalent to wall of equipment" should address most issues in that if a it is NEMA 3 enclosure, Water tight needed; if NEMA 1 then other means.
I'm not aware of a code reference that would require watertight specifically above a bus otherwise all standard romex or mc connectors, and the enclosure, would fail that requirement in a NEMA 1 enclosure. If water tight is a concern it would need to be a NEMA 3 enclosure and appropriate water tight connectors and closures.
 
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