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Thread: Marking out panel for conduit

  1. #11
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    So would you move your back line up an 1/8 " or back for 2" or smaller

  2. #12
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    Quote Originally Posted by liquidtite View Post
    So would you move your back line up an 1/8 " or back for 2" or smaller
    Yes, so if your strut were 1.5" and you made a line across 1.5" from the back of the panel you would adjust the line to be say 1/8" less or 1.375" from the panel back. This would allow the EMT to be plumb and the larger KO hole to be slightly closer to the back of the panel. If using 2.5" or larger EMT or RMC just run the line across the strut and that's the back of your KO.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  3. #13
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    Make your line, then measure the diameter of the raceway, half of that (the radius) is the center point of the hole.

    1/2 EMT is approximately 3/4" diameter, the center of your KO should be 3/8 of an inch from the line you made with the strut.

  4. #14
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    Quote Originally Posted by liquidtite View Post
    So for emt using the center point on the cutter of the knock out kit is most accurate .
    For a hole cutter or hole saw IMO yes.

    For punch sets I disagree with that because you cannot see this center mark with the punch die in the way and the center mark already drilled out.

    If I really want to do it perfect I use a square and a pencil to make a cross on the center mark and line the punch die indicating marks* up with the cross lines.


    (*If you look carefully at the side of a punch die you will find four small lines embossed on the edge of the die 90 degrees apart to line up the center. The marks are faint, often I hit them with my sharpie to make them stand out.)

  5. #15
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    I decided to check my tool box near me to see if I had a punch inside to show here. Even better I found a 2" die that still has my painters tape and sharpie mark pointing out the marks I was talking about.

    They are small and faint but I have found them on most if not all punches.
    Attached Images Attached Images  

  6. #16
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    When doing multiple KO's I like to draw a box for each hole on blue masking tape, find the center and then line up the CUTTER side of the KO tool with the lines. IMO this is the most accurate method. Here is 68 KO's, 34 KO's on each side for this large pull box. You can see the cutter in photo #2.

    Click image for larger version. 

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    Click image for larger version. 

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    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  7. #17
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    Quote Originally Posted by infinity View Post
    When doing multiple KO's I like to draw a box for each hole on blue masking tape, find the center and then line up the CUTTER side of the KO tool with the lines. IMO this is the most accurate method.
    I would say the results of your box method or using the factory punch center marks would be indistinguishable. Either is going to be on the money.

    Your method requires drawing more lines but is likely easier to see in low light.

  8. #18
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    Quote Originally Posted by iwire View Post
    I would say the results of your box method or using the factory punch center marks would be indistinguishable. Either is going to be on the money.

    Your method requires drawing more lines but is likely easier to see in low light.
    It depends how good your eyes are and how good the markings are on your KO set.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  9. #19
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    Quote Originally Posted by infinity View Post
    It depends how good your eyes are and how good the markings are on your KO set.
    Exactly.

    I was brought into using punches for everything.

    We would drill a 3/8" hole, punch that to 7/8" and then if needed punch that to 3/4" or larger. I moved into hole saws for 1/2" 3/4" and 1" but I have to step up my game and move to hole cutters.

  10. #20
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    Jun 2006
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    Ohio
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    Here's a NEMA Bulletin you may want to add to your digital toolbox...

    https://www.nema.org/Technical/Docum...d_12_15_11.pdf
    I will have achieved my life's goal if I die with a smile on my face.

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