Subpanel location, mounting on the joist

Discussion in 'Electrical Forum discussion & Blog' started by electrotuko, Jan 31, 2014.

  1. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,532
    Location:
    North Carolina
    I wonder why it is a bad idea to bundle NM cable

    [​IMG]

    There might be a good reason if one looks hard enough
  2. electrotuko

    electrotuko New Member

    Messages:
    47
    Location:
    Chicago, IL
    The reason very clearly seen from the picture: the bundle is tire-wrapped very tight, plus it runs through the insulation, not enough cooling, air circulation, wires even changed color from overheat. My is a bit different case, wires going through the non insulated/free air space, and was thinking to tire wrap them not completely, just create a loop and keep NM-B loose inside. But I got the point again, thanks for your comments.
    Homeownerinburb, thanks for advising NM cable support. I am afraid that would not be so convenient way, it will cerate an obstacle in the crawl, kind of something hanging down from the ceiling, some one can hurt his head. Better would be more flat implementation, for example:

    http://www.cyberguys.com/product-details/?productid=62778&rH=1645

    I will nail/staple them individually to joists instead, next to each other, 2" spacing out or so.
    How about 3/8" Metal flex, can I run them in a bundle, loosely bunched together and hung this under each joist?
    Last edited: Feb 2, 2014
  3. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,532
    Location:
    North Carolina
    either of the two devices with links driven to the side of the joist would work or even two cables under one staple.

    Dig out the required working space and install the panel if that is what trips your trigger.
  4. electrotuko

    electrotuko New Member

    Messages:
    47
    Location:
    Chicago, IL
    Exactly, that was the goal for having an elegant solution. Drill one hole in the floor to get to crawl space from the main panel. Run one 50' cable (easy to mount to each joist) through that hole to subpanel and from here easy split multiple NM-B's to all directions.
    Looks like the subpanel still an option.
    Few last things to clarify:
    It is not required to have a concrete floor in the area subpanel mounted? It is a gravel in the crawl.
    What is required minimum distance from the bottom/center of subpanel to the floor?
  5. DonL

    DonL Out of the Trades

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    "It is not required to have a concrete floor in the area subpanel mounted? "

    I think that must be a California thing.

    What part of Texas do you live in ?
  6. electrotuko

    electrotuko New Member

    Messages:
    47
    Location:
    Chicago, IL
    Last edited by a moderator: Feb 4, 2014
  7. DonL

    DonL Out of the Trades

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    Location:
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    Them should be just fine.

    Not sure why you could not use 4, Maybe JW can answer that.

    I did not see any rating, or approval.

    What forum says only 3 can be used ?

    Your Flag looks a lot like ours.
    Last edited: Feb 2, 2014
  8. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,532
    Location:
    North Carolina
    Concrete is not a code requirement.

    That makes things rough on the knees.
    Unless this is a mobile home there is no requirement on the minimum mounting height. The highest breaker can be no more than 6 feet 7 inches above grade but you could sit the panel on the ground if you so desired. In order to have the required working space the top of the panel must be below the floor joist.

    All of this is in the code section you referenced in your first post.
  9. Homeownerinburb

    Homeownerinburb New Member

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    525
    Location:
    Los Angeles, CA USA
    Wow. Now that is some inductive heating going on there!

    I wonder how many current carrying conductors are in there?

    That might have been legitimately derated to about four amps per conductor from the size of that bundle.
  10. DonL

    DonL Out of the Trades

    Messages:
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    Location:
    Houston, TX

    Mediterranean climate ? Are you kidding.

    I froze my butt off on the coast there with the wind blowing off of the water.

    It is a nice place to visit, but I would not want to live there.


    What are you going to do when they run out of drinkable water ?
  11. Homeownerinburb

    Homeownerinburb New Member

    Messages:
    525
    Location:
    Los Angeles, CA USA
    When you get to the end of your questions, and have only those specific to your region, you might want to go ask your local authority.

    Speaking of what CA is asking of us here now: when running NM under the floor in a crawl space, they want for us to install nailers such that nothing can be hung on the cable as it goes from one joist to the next.

    As I understand it, you need to secure the cable every 4' or there abouts. Not to each joist.
  12. electrotuko

    electrotuko New Member

    Messages:
    47
    Location:
    Chicago, IL
    jwelectric, you mentioned:

    But earlier you pointed out to 110.26(A)(1)(2)&(3) and noted:
    Just to clarify, can the subpanel be mounted 4 feet above the ground? How about the headroom of 6 1/2' you mentioned.
    It would be mounted on your suggested 3/4" ply board, making in the same high of my I eyes when sitting on the floor.
  13. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,532
    Location:
    North Carolina
  14. electrotuko

    electrotuko New Member

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    Location:
    Chicago, IL
  15. ImOld

    ImOld New Member

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    Location:
    In the rumble seat
    Interesting thread but............................

    If the OP is in fact in Chicago, you know, the city with it's own electrical code.

    Please don't reply with remarks such as "but it's just the same ".

    It's not.

    Something to ponder.
  16. electrotuko

    electrotuko New Member

    Messages:
    47
    Location:
    Chicago, IL
    The work is in a finishing up stage.
    Just curious if this is acceptable.
    The main panel is installed between studs on the outside wall. Now having added wires coming out to crawl.
    There are approx. 10 wires NM-B going down and 15 up from then panel. I was thinking of putting insulation in the area surrounding panel, between studs, were are the wires. Now worrying if this is OK to cover that whole area with the fiber glass insulation, since many wires over there, can get preheated. Wires not bundled, going in a parallel pattern. Is this Ok to insulation as per NEC?
  17. DonL

    DonL Out of the Trades

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    Location:
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    Can you take pictures ?


    Good Luck on your project.
  18. electrotuko

    electrotuko New Member

    Messages:
    47
    Location:
    Chicago, IL
    I can take few pictures, in a few least questionable areas, to void some criticism...:)

    Just to reiterate my worry:
    Can I cover the area (insulate wall) with fiberglass R-16 below and above the panel where many NM-B wires going up/down from the panel. Afraid to have temp rise or so. Is NEC OK with this?
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