knock out seal

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  #1  
Old 04-14-11, 06:31 PM
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knock out seal

I have a question about knock out seals for metal boxes.



I have an existing 1-1/2" 4x4 box, with a 1-1/2" extension ring on it, making it double deep. I need to move a rigid conduit from a back hole to a front hole.

Out of the six holes on top, five of them are occupied, it is fairly congested in there. After I removed the old conduit, I tried to use a knock out seal to cover the back hole on top. I nudged the wires over to the side and tried to push it up into the hole, but you know this thing is so tight, and there is no leverage to tap it with a screw driver because there are two boxes deep and the hole is in the back, on top. I tried for a good 15 minutes and gave up!

I know I can put it in from the outside, but the "claws" inside may nip wires.

Is there a better way? Can I just tape the hole shut with electrical tape?
 
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Old 04-14-11, 06:42 PM
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I know I can put it in from the outside, but the "claws" inside may nip wires.
Knockout closers are normally always installed from the outside. Don't use electrical tape.
 
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Old 04-14-11, 06:48 PM
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Plastic KO seals are MUCH easier to install and are UL approved. We buy them buy the box load.

I hope your box is not over filled. A 4"x4"x 1 1/2" box is allowed only 9 #12 or 10 #14 (also adding for devices) If your extension ring is the same depth your are looking at about double for your max wire count.
 
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Old 04-14-11, 07:07 PM
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if you install it from the outside, when you push it in, and later on you had to move wires to the back wouldn't it have a good chance of nipping the wires?

I thought the proper way is to install it from the inside out, and then flatten the claws from the outside, no?
 
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Old 04-14-11, 07:10 PM
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Originally Posted by Tolyn Ironhand View Post
Plastic KO seals are MUCH easier to install and are UL approved. We buy them buy the box load.

I hope your box is not over filled. A 4"x4"x 1 1/2" box is allowed only 9 #12 or 10 #14 (also adding for devices) If your extension ring is the same depth your are looking at about double for your max wire count.
I don't have that many wires. I needed an extension ring because I am using a GFCI outlet which is quite "boxy". The wires back there I may have 10 or so, but it's not the number of wires, sometimes it's the length of the wires, with over half of them existing solid #12 wires they are not as easy to fold or tuck as the stranded wires.

Where would I get plastic knock out seals? I looked at the big box store, couldn't find any.
 
  #6  
Old 04-14-11, 08:07 PM
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Snap-in seals may be inserted from either side of the box, the "claws" do not present any significant danger to the insulation on the wires. It is not supposed to be necessary to bend the claws back but I so often find that I need to bend the claws inward just to get the seal in place that bending them back may not be a bad idea.

Years ago the snap-in seals were fairly easy to install but the ones manufactured recently (or at least the ones readily available at the homecenter) are a real bear to get in. I actually prefer the type that has a screw through the middle with a cross-bar but I never see them at the homecenter.
 
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Old 04-15-11, 02:18 PM
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Try a supply house.

And here we have more characters.
 
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