Results 1 to 4 of 4

Thread: Sizing building steel bond

  1. #1

    Sizing building steel bond

    Im trying to size my bond to building steel for a 400 amp sevice. From the meter the service conductors enter the building in parallel sets of 3 phase 3/0. Each set going to their own main breaker 200 amp panel. My thinking is that the wire should be a 1/0 to building steel since it is a parallel set, three 3/0 ungrounded conductors is equivalent to a 600 kcmil. 250.66 then tells me 1/0 to both panels (not allowed to bond in meter)

  2. #2
    Join Date
    Jan 2009
    Location
    3 Hr 2 Min from Winged Horses
    Posts
    15,218
    You could do that or tap from each panel with #4 to a common 1/0.

    Like this shows

    "Electricity is really just organized lightning." George Carlin


    Derek

  3. #3
    Join Date
    May 2005
    Location
    Richmond, Virginia
    Posts
    23,355
    Or three individual #4s to the building steel.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  4. #4
    Join Date
    Jul 2003
    Location
    New Jersey
    Posts
    25,820
    Quote Originally Posted by slc410 View Post
    Im trying to size my bond to building steel for a 400 amp service. From the meter the service conductors enter the building in parallel sets of 3 phase 3/0. Each set going to their own main breaker 200 amp panel. My thinking is that the wire should be a 1/0 to building steel since it is a parallel set, three 3/0 ungrounded conductors is equivalent to a 600 kcmil. 250.66 then tells me 1/0 to both panels (not allowed to bond in meter)
    I'm confused, you said that you have parallel sets but them you stated that "each set going to their own main breaker 200 amp panel." How many sets are you running and are they connected together on both ends?
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

Posting Permissions

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