Page 1 of 4 123 ... LastLast
Results 1 to 10 of 34

Thread: System Bonding Jumper

  1. #1
    Join Date
    Oct 2008
    Location
    Brooklyn, NY
    Posts
    883

    System Bonding Jumper

    Let's assume you have a separately derived system consisting of a transformer in it's own enclosure and a disconnect(or overcurrent) device in a separate enclosure. You have two jumpers. One from the transformer neutral to it's own enclosure and the other from the transformer neutral through any connecting conduit to the disconnect/overcurrent enclosure and then connected to the equipment grounding terminal bar. Which of these is the system bonding jumper?
    Eric Kench, P.E.


    If it's not broken don't fix it

  2. #2
    Join Date
    Jul 2005
    Location
    Tennessee
    Posts
    12,798
    according to tjhis...it's an either or:

    Name:  transformer.jpg
Views: 1897
Size:  141.4 KB
    At my age, I'm accustomed to restaurants asking me to pay in advance, but now my bank has started sending me their calendar one month at a time.

  3. #3
    Join Date
    Oct 2008
    Location
    Brooklyn, NY
    Posts
    883
    System bonding jumper inside the disconnect enclosure is easy enough. It's just a jumper from the neutral terminal bar to the EGC bar.
    Eric Kench, P.E.


    If it's not broken don't fix it

  4. #4
    Join Date
    Jul 2009
    Location
    Ware Shoals, South Carolina
    Posts
    1,085
    The system bonding jumper is located in the enclosure that contains the GEC.
    Advise is a dangerous gift, even from the wise to the wise.

  5. #5
    Join Date
    Oct 2008
    Location
    Brooklyn, NY
    Posts
    883
    Quote Originally Posted by SG-1 View Post
    The system bonding jumper is located in the enclosure that contains the GEC.
    Actually the GEC is located at the enclosure containing the system bonding jumper.

    The problem here is that I came across an old diagram from the 1990s that shows an SBJ running from the transformer neutral to the EGC terminal bar located at the disconnect. If it's in separate enclosures then which enclosure do you connect the grounding electrode conductor?
    Last edited by erickench; 05-09-10 at 07:03 PM.
    Eric Kench, P.E.


    If it's not broken don't fix it

  6. #6
    Join Date
    Jun 2006
    Location
    Ohio
    Posts
    13,123
    Quote Originally Posted by erickench View Post
    Actually the GEC is located at the enclosure containing the system bonding jumper.

    The problem here is that I came across an old diagram from the 1990s that shows an SBJ running from the transformer neutral to the EGC terminal bar located at the disconnect. If it's in separate enclosures then which enclosure do you connect the grounding electrode conductor?
    A grounding conductor between two different enclosures on the line side of the system disconnecting means is an equipment bonding jumper (EBJ)... no matter what the diagram calls it.
    I'll never get there. No matter where I go, I'm always here.

  7. #7
    Join Date
    Oct 2008
    Location
    Brooklyn, NY
    Posts
    883
    Quote Originally Posted by Smart $ View Post
    A grounding conductor between two different enclosures on the line side of the system disconnecting means is an equipment bonding jumper (EBJ)... no matter what the diagram calls it.
    Yes, I would agree with that. I would size it in accordance with NEC Table 250.66 and refer to it as a "Supply Side Bonding Jumper" as defined in NEC 250.102(C).
    Eric Kench, P.E.


    If it's not broken don't fix it

  8. #8
    Join Date
    Feb 2003
    Location
    Illinois
    Posts
    19,330
    Quote Originally Posted by erickench View Post
    Actually the GEC is located at the enclosure containing the system bonding jumper.

    The problem here is that I came across an old diagram from the 1990s that shows an SBJ running from the transformer neutral to the EGC terminal bar located at the disconnect. If it's in separate enclosures then which enclosure do you connect the grounding electrode conductor?
    The GEC is connected in the enclosure where the grounded and grounding conductors are connected to each other. The grounding and grounded conductors, in the case of a transformer, can be connected to each other at either the transformer or the OCPD, but not both. No mater where the GEC is connected, a bonding jumper will be required between the transformer and the OCPD.
    Don, Illinois
    "It is the first responsibility of every citizen to question authority." B Franklin

  9. #9
    Join Date
    Oct 2008
    Location
    Brooklyn, NY
    Posts
    883
    So regardless of where the SBJ is located in either the transformer or OCPD enclosures there will always be an equipment bonding jumper between the enclosures and this jumper is sized according to NEC Table 250.66.
    Eric Kench, P.E.


    If it's not broken don't fix it

  10. #10
    Join Date
    Feb 2003
    Location
    Illinois
    Posts
    19,330
    Quote Originally Posted by erickench View Post
    So regardless of where the SBJ is located in either the transformer or OCPD enclosures there will always be an equipment bonding jumper between the enclosures and this jumper is sized according to NEC Table 250.66.
    That is correct.
    Don, Illinois
    "It is the first responsibility of every citizen to question authority." B Franklin

Posting Permissions

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