User Tag List

Page 1 of 2 1 2 LastLast
Results 1 to 10 of 12

Thread: proper use of bonding wire in LFMC? just grounded locknuts?

  1. #1
    Join Date
    Dec 2016
    Location
    pittsburgh, pa
    Posts
    110
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    proper use of bonding wire in LFMC? just grounded locknuts?

    never dealt with the LFMC that has the bonding wire in it so not sure what proper installation is? is landing it on the fittings grounded locknut at both ends sufficient?

  2. #2
    Join Date
    Feb 2009
    Location
    Durango, CO, 10 h 20 min without traffic from winged horses.
    Posts
    10,121
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    You don't do anything with it. It's not an equipment ground that runs the length of the flex, it's there to make a strip that shorts each of the turns in the flex together.
    If you don't think too good, don't think too much.

  3. #3
    Join Date
    Jul 2003
    Location
    New Jersey
    Posts
    27,539
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by emiller233 View Post
    never dealt with the LFMC that has the bonding wire in it so not sure what proper installation is? is landing it on the fittings grounded locknut at both ends sufficient?
    What do you mean by a bonding wire, is it an EGC? Otherwise there are limits (length, ampacity, and size) as to when LFMC can be used as an EGC. Look at 250.118.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  4. #4
    Join Date
    Dec 2016
    Location
    pittsburgh, pa
    Posts
    110
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    we're not planning on using it as an EGC as out cables have the grounds in them. but the customer just sent us this spec asking for the ground in the LFMC. lengths will be roughly 10' max. and most devices are for instrumentation devices, and will be fed back to a wireway to get back to the terminal block enclosures. There are a few 480vac motors and heaters using single conductor SIS pulled thru this LFMC as well.

    this is the LFMC that is awaiting the customers approval (3/8" and 1" sizes)
    http://flexiblewiringconduits.anacon...017%20ZHUA.pdf

    R-2.3-14
    [All cables shall be contained within raceway which shall be Rigid Galvanized Steel (RGS) and liquid
    tight metal braided flexible conduit (with grounding wire). Flexible conduit shall not extend more than
    three feet without being supported and is only to be used as a final connection to a device and not run
    throughout the subassemblies.]

  5. #5
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    41,664
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by ActionDave View Post
    You don't do anything with it. It's not an equipment ground that runs the length of the flex, it's there to make a strip that shorts each of the turns in the flex together.
    I'll second that. It is only there to improve impedance of the flex itself. NEC still has limits on the use of the flex alone as an EGC.
    I live for today, I'm just a day behind.

  6. #6
    Join Date
    Feb 2009
    Location
    Durango, CO, 10 h 20 min without traffic from winged horses.
    Posts
    10,121
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by emiller233 View Post
    we're not planning on using it as an EGC as out cables have the grounds in them. but the customer just sent us this spec asking for the ground in the LFMC. lengths will be roughly 10' max. and most devices are for instrumentation devices, and will be fed back to a wireway to get back to the terminal block enclosures. There are a few 480vac motors and heaters using single conductor SIS pulled thru this LFMC as well.

    this is the LFMC that is awaiting the customers approval (3/8" and 1" sizes)
    http://flexiblewiringconduits.anacon...017%20ZHUA.pdf

    R-2.3-14
    [All cables shall be contained within raceway which shall be Rigid Galvanized Steel (RGS) and liquid
    tight metal braided flexible conduit (with grounding wire). Flexible conduit shall not extend more than
    three feet without being supported and is only to be used as a final connection to a device and not run
    throughout the subassemblies.]
    Sounds like they want you to pull a green in the LTFMC. That's different than the bonding strip that is wound inside the coils of the flex. I don't see anything that says you need a bondindg locknut.
    If you don't think too good, don't think too much.

  7. #7
    Join Date
    Dec 2016
    Location
    pittsburgh, pa
    Posts
    110
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by ActionDave View Post
    Sounds like they want you to pull a green in the LTFMC. That's different than the bonding strip that is wound inside the coils of the flex. I don't see anything that says you need a bondindg locknut.
    we could do that, but whats the different between pulling a green wire and using the LFMC as an EGC? some of the instrumentation devices that we'll be wiring into do not have a ground stud in them either...

  8. #8
    Join Date
    Feb 2009
    Location
    Durango, CO, 10 h 20 min without traffic from winged horses.
    Posts
    10,121
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Practically speaking there is no difference other than the restrictions that liquid tite not be used as an egc over 20A or more than six feet, but the Cult of The Green Wire and their fellow brethren, Dirt Worshippers have an enormous influence.
    If you don't think too good, don't think too much.

  9. #9
    Join Date
    Jul 2003
    Location
    New Jersey
    Posts
    27,539
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by emiller233 View Post
    we could do that, but whats the different between pulling a green wire and using the LFMC as an EGC? some of the instrumentation devices that we'll be wiring into do not have a ground stud in them either...
    No difference in my book but did you check out the code section in post #3? LFMC has limits when used as an EGC.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  10. #10
    Join Date
    Dec 2016
    Location
    pittsburgh, pa
    Posts
    110
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    i did, i can deal with the 6' max length. can add a chunk of RMC if needed to shorten the LFMC length

Tags for this Thread

Posting Permissions

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