(206) 949-5683, Top Rated Plumber, Seattle
Page 2 of 2 FirstFirst 12
Results 16 to 18 of 18

Thread: Load Center Wiring Questions

  1. #16
    Electrician Chris75's Avatar
    Join Date
    Aug 2007
    Location
    Litchfield, CT
    Posts
    608

    Default

    Quote Originally Posted by Mikey View Post
    May be very hard, but very common, and have apparently passed inspection. Can you give me the chapter & verse on that citation? There must be a loophole...
    check out 312 .5(C) You dont need a loophole, you just need to follow the code, and its usually hard to meet the requirements

  2. #17
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
    Join Date
    Nov 2005
    Location
    Central Florida
    Posts
    2,685

    Default

    Thanks for the cite. I've spent some quality time on Mike Holts' forum and, as usual, find the discussions fascinating and the Code in desperate need of work beyond the normal revision cycle.

    312(5)(C)(b) immediately rains out the parade by prohibiting penetration of a structural ceiling, which is the reason for using the conduit in the first place. I can't believe that any reasonable person would prefer 30-40 individual cables making their way out of the attic space into individual knockouts on the panel to running them through several large conduits. But, is a garage ceiling "structural"? At least one NEC expert says no. If there's no drywall on the ceiling and the conduits pass between the joists, are they "penetrating" the ceiling? Maybe, maybe not.

    312(5)(C)(g) says to use Table 1 of Chapter 9 to determine conduit fill; Note 2 to Table 1 says Table 1 is "not intended to apply to sections of conduit or tubing used to protect exposed wiring from physical damage", which seems to be the case here, since 312.5 starts out by saying "conductors... shall be protected from abrasion...".

    Finally, the entire Exception under 312.5(C) applies to a "surface mounted" enclosure. If the service panel is mounted between 2 framing members, is it "surface mounted"? What if the panel is mounted on the surface of a masonry wall, on which a finish wall is later constructed so that the panel is ultimately flush with the finished surface?

    Bottom line, as usual, seems to be that the Code is pretty vague and conflicting in may instances; ultimately, if your AHJ likes it, it's OK. There seem to be lots of conflicts in both directions -- one inspector mentioned on Mike's forum, for example, will not accept plastic boxes with the integral cable clamps, even though they're UL approved, Listed, and still have a few drops of holy water on them.
    Last edited by Mikey; 02-10-2008 at 06:19 AM.

  3. #18
    Electrician Chris75's Avatar
    Join Date
    Aug 2007
    Location
    Litchfield, CT
    Posts
    608

    Default

    Quote Originally Posted by Mikey View Post

    312(5)(C)(b) immediately rains out the parade by prohibiting penetration of a structural ceiling, which is the reason for using the conduit in the first place. I can't believe that any reasonable person would prefer 30-40 individual cables making their way out of the attic space into individual knockouts on the panel to running them through several large conduits.
    You get used to it, its really not that hard, to me it would be harder later on to add/remove circuits that were all installed in a conduit.

    Quote Originally Posted by Mikey View Post
    But, is a garage ceiling "structural"? At least one NEC expert says no. If there's no drywall on the ceiling and the conduits pass between the joists, are they "penetrating" the ceiling? Maybe, maybe not.
    Definition: The overhead surface in a room, made from any of several materials, as wood or plaster.

    Quote Originally Posted by Mikey View Post
    312(5)(C)(g) says to use Table 1 of Chapter 9 to determine conduit fill; Note 2 to Table 1 says Table 1 is "not intended to apply to sections of conduit or tubing used to protect exposed wiring from physical damage", which seems to be the case here, since 312.5 starts out by saying "conductors... shall be protected from abrasion...".
    Yes. BUT, 312.5(C)(g) is telling you to use the table...



    Quote Originally Posted by Mikey View Post
    Finally, the entire Exception under 312.5(C) applies to a "surface mounted" enclosure. If the service panel is mounted between 2 framing members, is it "surface mounted"?
    It means what it says, the panel MUST be surface mounted...

    Quote Originally Posted by Mikey View Post
    What if the panel is mounted on the surface of a masonry wall, on which a finish wall is later constructed so that the panel is ultimately flush with the finished surface?
    I dont worry about what if's... cross that bridge when it happens...

    Quote Originally Posted by Mikey View Post
    Bottom line, as usual, seems to be that the Code is pretty vague and conflicting in may instances; ultimately, if your AHJ likes it, it's OK. There seem to be lots of conflicts in both directions -- one inspector mentioned on Mike's forum, for example, will not accept plastic boxes with the integral cable clamps, even though they're UL approved, Listed, and still have a few drops of holy water on them.
    Listen, I have never met an AHJ, only inspectors, they can only inspect, not change the rules as they go, so if there is no state amendment, then they are making their own rules which is so wrong.... and its not OK if an inspector thinks its OK, its a code violation and they are not doing their job....

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •