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Thread: Concentric KO's

  1. #1
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    Concentric KO's

    I fail to understand why manufacturers can't get concentric KOs right. Twice yesterday, the entire KO ring blew out while I was trying to remove just the center. Now I have sets of 2" --> 1" and 2" --> 1-1/2" reducing washers installed. I hate these things with a passion. Just let me punch my own holes if it's so hard to engineer a concentric KO that isn't terrible; at least then I know they'll always come out the right size. That's why I always buy enclosures with no KO's.

    The concentric KO's in 4" sq. boxes work great. Why can't that technology be applied to breaker panels and ATS enclosures?!

    <rant off/>


    SceneryDriver

  2. #2
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    I guess you had a fight with couple of KOs and you got KOed out by both???

    It is ok. Have a beer or two.

    I know, sometimes all come out but you just wanted a 1" and now you have to get a 3" to 1" reducer.
    Edward
    The only thing I know, is the progressive discovery of my ignorance


  3. #3
    Join Date
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    Oh, they were probably OK for the first couple hundred boxes, then the dies started to wear.... a couple thousand later, they're not so good.

  4. #4
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    Quote Originally Posted by SceneryDriver View Post
    I fail to understand why manufacturers can't get concentric KOs right. Twice yesterday, the entire KO ring blew out while I was trying to remove just the center. Now I have sets of 2" --> 1" and 2" --> 1-1/2" reducing washers installed. I hate these things with a passion. Just let me punch my own holes if it's so hard to engineer a concentric KO that isn't terrible; at least then I know they'll always come out the right size. That's why I always buy enclosures with no KO's.

    The concentric KO's in 4" sq. boxes work great. Why can't that technology be applied to breaker panels and ATS enclosures?!

    <rant off/>


    SceneryDriver
    I agree with you, many of them are terrible to remove. Often I will bend them slightly and then cut each section of the concentric ring with my dykes to isolate one little tab at a time. The tangential type usually on Square D stuff seem to be better but IMO when you're done the holes are somewhat sloppy.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  5. #5
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    IMO, this happens periodically when the punch is getting dull. Not sure how they check these things but I usually find that they work okay most of the time.
    They say I shot a man named Gray and took his wife to Italy
    She inherited a million bucks and when she died it came to me
    I can't help it if I'm lucky



  6. #6
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    An EC friend I know hates them so bad, he uses a hole punch on them and doesn't even try the screwdriver method.

    For me, some of them come out fine with care, but I have had some that were horrible. I have had some that were so bad, the bottom of the panel would dent before the ring would pop.
    Cheers and Stay Safe,

    Marky the Sparky

  7. #7
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    Just yesterday I drilled out a "pre-punched" 1/4 inch KO for a grounding conductor that did not want to "knock out".

  8. #8
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    Quote Originally Posted by SceneryDriver View Post
    I fail to understand why manufacturers can't get concentric KOs right. Twice yesterday, the entire KO ring blew out while I was trying to remove just the center. Now I have sets of 2" --> 1" and 2" --> 1-1/2" reducing washers installed. I hate these things with a passion. Just let me punch my own holes if it's so hard to engineer a concentric KO that isn't terrible; at least then I know they'll always come out the right size. That's why I always buy enclosures with no KO's.

    The concentric KO's in 4" sq. boxes work great. Why can't that technology be applied to breaker panels and ATS enclosures?!

    <rant off/>


    SceneryDriver
    I dislike premanufactured conduit entries too. It means you have to know exactly where your conduits go, if you are trying to plan alignment of your equipment in advance of having it available. Also an issue if another trade is going to build your conduits embedded in a wall or slab, in advance of your equipment showing up on site. And good luck finding this information on a datasheet. It also means that if the over 250V rules apply, you need additional grounding means that you wouldn't need if you could make your own hole.

    Another issue is if the manufacturer anticipates a different mix of sizes than you do. I've seen equipment that has a field full of 1/2" only KOs and only one larger KO. All I wanted to do was 1" in and 1" out.
    Last edited by Carultch; 04-21-17 at 12:55 PM.

  9. #9
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    I have found that drilling out the points, that connect one ko to the next size, using a ⅛" bit, helps tremendously. Not sure how better to describe what we do.
    ABC

    "Eschew Obfuscation!"

  10. #10
    Join Date
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    Quote Originally Posted by electricguy61 View Post
    I have found that drilling out the points, that connect one ko to the next size, using a ⅛" bit, helps tremendously. Not sure how better to describe what we do.
    Thank you for an actual good idea.

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