ko seals requirments on MC clamp type boxes

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twompz

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I cannot find a code refrence that addresses the issue of mc clamp type metal boxe Knockouts(the one you remove with flat screwdriver) needing a knockout seal, if it is removed then how do I find a ko seal for it?

The Mc clamp holds 2 mc cables and inspector said if I used one ko for mc and the other was empty I would have to replace entire box, does that sound right.

and if only one ko was missing and the other was not used that I had to screw the mc clamp down.

thanks paul:cool:
 
That sounds right to me. Either that, or rotate the box 180 degrees, use the other clamp for your MC, and screw the boo-boo clamp in the whole way to cover up the holes.
 
twompz said:
I cannot find a code refrence that addresses the issue of mc clamp type metal boxe Knockouts(the one you remove with flat screwdriver) needing a knockout seal, if it is removed then how do I find a ko seal for it?
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The article is 314.17(A). I would think any kind of duct seal, fire stop, or silicone, would be fine.

(A) Openings to Be Closed. Openings through which conductors enter shall be adequately closed.
 
chevyx92 said:
I doubt thats the solution and far from it. JMO.
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Why not.. Not pretty but it would effectively seal the whole. I also think silicone would work. I have in a pinch used metal type duct tape.
 
Dennis Alwon said:
Why not.. Not pretty but it would effectively seal the whole. I also think silicone would work. I have in a pinch used metal type duct tape.
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I don't think that is a real big safety issue, but IMO may run afoul of 110.12(A).
 
twompz said:
I cannot find a code refrence that addresses the issue of mc clamp type metal boxe Knockouts(the one you remove with flat screwdriver) needing a knockout seal, if it is removed then how do I find a ko seal for it?

The Mc clamp holds 2 mc cables and inspector said if I used one ko for mc and the other was empty I would have to replace entire box, does that sound right.

and if only one ko was missing and the other was not used that I had to screw the mc clamp down.

thanks paul:cool:
Click to expand...

http://www.hubbellcatalog.com/raco/raco_datasheet.asp?PN=1042&FAM=RacoFittings&P=6433,7652
 
brian john said:
Super glue a flat washer over the hole?
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Super glue and washer is an approved method? UL listed? Don't believe so. We all can come up with ridiculous ways to seal it. He's looking for the right way. Don't turn him into a hack. :)
 
Turn the box upside down so the inspector won't see it :roll:

A nut, bolt and 2 small washers would have to be legal.
 
Well if nobody wants to hack up the installation, then just change out the box and save it for another spot!!:smile:
 
mdshunk said:
That sounds right to me. Either that, or rotate the box 180 degrees, use the other clamp for your MC, and screw the boo-boo clamp in the whole way to cover up the holes.
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IMO even leaving it in place with the empty hole and the other cable installed - the clamp would be adiquate closure. MC KO's aren't big, and closing it little more than half way with the clamp would not allow much in there.... One cable would make the clamp cock to one side, and effectively IMO close the hole to the point that just short of a well maniplulated coat hanger is gonna get in there.

"effectively closed" can mean lots of things...

Short of that - the clamp is made to do the job sans cable - with that little shield against the bottom - take a pair of tin snips and invert it on one side.
 
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