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  1. #1
    RobertSmith's Avatar
    RobertSmith Guest

    Default Electrical cable routing

    Last edited by RobertSmith; 12-20-2007 at 01:44 PM.
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  2. #2
    Join Date
    Mar 2007
    Location
    Spring Hill (Nashville), TN
    Posts
    5,851

    Default Re: Electrical cable routing

    Yes, it is a problem. They can be pinched or damaged.

    Scott Patterson, ACI
    Spring Hill, TN
    www.traceinspections.com

  3. #3
    Join Date
    Mar 2007
    Location
    Fletcher, NC
    Posts
    28,032

    Default Re: Electrical cable routing

    Quote Originally Posted by RobertSmith View Post
    electrical cables are routed between the two walkboards?
    Walkboards? As in "in the attic"?

    If so, those need to be routed elsewhere and/or protected from physical damage (so you don't damage them while walking on that floor surface. That floor surface (walkboards) leads to/from where?

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  4. #4
    Mike Parks's Avatar
    Mike Parks Guest

    Default Re: Electrical cable routing

    Use "(H) Bends. No bend shall have a radius of less than five
    times the cable diameter.", from 551.47 Wiring Methods.
    I know it says through studs but it is a good rule.


  5. #5
    Join Date
    Mar 2007
    Location
    Fletcher, NC
    Posts
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    Default Re: Electrical cable routing

    Quote Originally Posted by Mike Parks View Post
    Use "(H) Bends. No bend shall have a radius of less than five times the cable diameter.", from 551.47 Wiring Methods.
    I know it says through studs but it is a good rule.
    Er ... Mike, Did you look to see where 551 applies?











    ARTICLE 551 Recreational Vehicles and Recreational Vehicle Parks

    Now, if you want wire bending limitations, you have to go to 110.3(B) and then to the manufacturers.

    There's more to the attached than just the table but the file size was too large to upload, and the table gives all that is really needed anyway. On the left column is the thickness of the insulation - almost every insulation seen in residential use will be the thinner thickness; the columns to the right are the overall diameter of the cable/conductor (including insulation), and almost every conductor/cable in residential use will be in the farthest left column - 1" and smaller; thus, the minimum wire bending RADIUS is 4 times the DIAMETER of the conductor/cable. The problem I find with most electricians is that they use 4 times the conductor diameter as the 'diameter' of the bend, not the 'radius' of the bend - big difference.

    Example 1: 2/0 is about 1/2" in diameter, its minimum bending radius is 4 times that, or 2", meaning a 4" diameter circle, if bent in a 'U' shape.

    Example 2: NM cable - when bending in the flatways direction, use that cable thickness; when bending in the sideways direction, use that much larger cable width. Makes a HUGE difference in the minimum bending radius.

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    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

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