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Thread: Residential garage

  1. #11
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    Quote Originally Posted by dm9289 View Post
    Yes if you look at the beam picture I posted it would be similar to that with a drywall ceiling. Lets say 8 NM cables typically tie wrapped to create the bundle. I am not sure how to derate no conduit
    Same way you "derate" conductors in a conduit. If you have eight 12-2 cables bundled together you have 16 current carrying conductors and adjustment factor for that is 50%.

    If you break it into two separate bundles and maintain spacing so that it remains as two separate bundles now you only have 8 current carrying conductors in each bundle and adjustment is 70% - that works out to not needing to increase conductor size for NM-B.

    Reality is you probably never produce enough heat to be an issue unless they are all feeding HVAC or other continuous loads, but that is not what NEC says....
    I live for today, I'm just a day behind.

  2. #12
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    Hawthorne, New York NEC: 2014
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    Quote Originally Posted by dm9289 View Post
    The picture I posted is an example of the beam but the finished garage ceiling is what is different. Typically you will see 8 NM cables tie wrapped across the beam then 90 degree angle attached in corner of ceiling and block wall then a 90 downward to panel. Hope this clears my description up.
    Nope. Even more confusing. How about a picture?

    -Hal

  3. #13
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    3M cable stackers, but you can bundle w/ tywraps.

  4. #14
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    Quote Originally Posted by dm9289 View Post
    The basement/ garage area of a common “A” frame home in my area has a steel beam running thru the center of the home at a 90 degree angle to floor joists. In the basement laundry part bored holes are common rules pretty straight forward.

    But the typical garage has a finished ceiling and the nm cables are attached/ bundled between finished ceiling and steel beam exposed. Is this code compliant?

    After the steel beam ends wires are bundled run along wall finished ceiling height to service panel drop about a foot then enter panel is this OK

    334.15C gives some good info as does 300.4 but I’m having trouble. With the garages here having finished ceilings and the above methods seeming so common and probably incorrect is what causes me confusion

    Thanks for your help
    If you are saying they are only bundled for a foot then you are ok. That is the same as a sleeve less than 24" NEC 310.15(B)(3) in 2014, adjustment factors, more than 3 current carrying conductors.

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