Page 1 of 2 12 LastLast
Results 1 to 10 of 20

Thread: 10' Tap rule

  1. #1
    Join Date
    Jul 2003
    Location
    New Jersey
    Posts
    19,123

    10' Tap rule

    I have an installation where I need to apply the 10' tap rule. The device fed by the tap conductors is rated at 100 amps (no OCPD), the device has a calculated load of less then 100 amps, the feeder conductors are protected at 400 amps and the tap conductors are rated for 100 amps. Is this code compliant? I say it complies with 240.21 but I've gotten some other opinions regarding the omission of and OCPD where the tap conductors terminate. Specifically 240.21(B)(1)(a) and (b).

    240.21 Location in Circuit.
    Overcurrent protection shall be provided in each ungrounded circuit conductor and shall be located at the point where the conductors receive their supply except as specified in 240.21(A) through (H). Conductors supplied under the provisions of 240.21(A) through (H) shall not supply another conductor except through an overcurrent protective device meeting the requirements of 240.4.
    (A) Branch-Circuit Conductors. Branch-circuit tap conductors meeting the requirements specified in 210.19 shall be permitted to have overcurrent protection as specified in 210.20.
    (B) Feeder Taps. Conductors shall be permitted to be tapped, without overcurrent protection at the tap, to a feeder as specified in 240.21(B)(1) through (B)(5). The provisions of 240.4(B) shall not be permitted for tap conductors.
    (1) Taps Not over 3 m (10 ft) Long. Where the length of the tap conductors does not exceed 3 m (10 ft) and the tap conductors comply with all of the following:
    (1) The ampacity of the tap conductors is
    a. Not less than the combined calculated loads on the circuits supplied by the tap conductors, and
    b. Not less than the rating of the device supplied by the tap conductors or not less than the rating of the overcurrent protective device at the termination of the tap conductors.
    (2) The tap conductors do not extend beyond the switchboard, panelboard, disconnecting means, or control devices they supply.
    (3) Except at the point of connection to the feeder, the tap conductors are enclosed in a raceway, which shall extend from the tap to the enclosure of an enclosed switchboard, panelboard, or control devices, or to the back of an open switchboard.
    (4) For field installations where the tap conductors leave the enclosure or vault in which the tap is made, the rating of the overcurrent device on the line side of the tap conductors shall not exceed 10 times the ampacity of the tap conductor.
    FPN: For overcurrent protection requirements for panelboards, see 408.36.
    (2) Taps Not over 7.5 m (25 ft) Long. Where the length of the tap conductors does not exceed 7.5 m (25 ft) and the tap conductors comply with all the following:
    (1) The ampacity of the tap conductors is not less than one-third of the rating of the overcurrent device protecting the feeder conductors.
    (2) The tap conductors terminate in a single circuit breaker or a single set of fuses that limit the load to the ampacity of the tap conductors. This device shall be permitted to supply any number of additional overcurrent devices on its load side.
    (3) The tap conductors are protected from physical damage by being enclosed in an approved raceway or by other approved means.
    Rob

    Chief Moderator

    All responses based on the 2011 NEC unless otherwise noted

  2. #2
    Join Date
    Jun 2005
    Location
    Delmarva, USA
    Posts
    1,645
    Quote Originally Posted by infinity View Post
    I have an installation where I need to apply the 10' tap rule. The device fed by the tap conductors is rated at 100 amps (no OCPD).....

    From your quote:

    ....(2) The tap conductors terminate in a single circuit breaker or a single set of fuses that limit the load to the ampacity of the tap conductors. This device shall be permitted to supply any number of additional overcurrent devices on its load side....
    Hmmm .... that only applies to the 25 foot taps ....

    I see your dilemma upon further re-reading of the section of the Code ...
    Last edited by kbsparky; 08-14-10 at 10:27 PM.

  3. #3
    Join Date
    Jul 2005
    Location
    Tennessee
    Posts
    12,611
    What is the "device" at termination ?
    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.

  4. #4
    Join Date
    Jul 2003
    Location
    New Jersey
    Posts
    19,123
    Quote Originally Posted by kbsparky View Post
    From your quote:


    ....(2) The tap conductors terminate in a single circuit breaker or a single set of fuses that limit the load to the ampacity of the tap conductors. This device shall be permitted to supply any number of additional overcurrent devices on its load side....
    Hmmm .... that only applies to the 25 foot taps ....

    I see your dilemma upon further re-reading of the section of the Code ...
    That's where I was going with this. The requirement for an OCPD in the 25' rule but not in the 10' rule.

    Quote Originally Posted by augie47 View Post
    What is the "device" at termination ?
    This is for a 100 amp rated dimming panel tapped from a 400 amp feeder.
    Rob

    Chief Moderator

    All responses based on the 2011 NEC unless otherwise noted

  5. #5
    Join Date
    Jul 2005
    Location
    Tennessee
    Posts
    12,611
    If it's associated with Art 520 (Theaters, Audience Areas of Motion Picture and Television Studios, Performance Areas, and Similar Locations), it appears 520.25 would require a OCP & Disconnect.
    Beyond that my next step would be the UL classification and see if that equipmemt requires OCP.
    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.

  6. #6
    Join Date
    Jul 2003
    Location
    New Jersey
    Posts
    19,123
    Quote Originally Posted by augie47 View Post
    If it's associated with Art 520 (Theaters, Audience Areas of Motion Picture and Television Studios, Performance Areas, and Similar Locations), it appears 520.25 would require a OCP & Disconnect.
    Beyond that my next step would be the UL classification and see if that equipmemt requires OCP.
    Not sure that 520.25 would apply to this installation since each individual dimmer has it's own OCPD. The dimming panel has no OCPD except for the 400 amp device ahead of the feeder conductors. This dimming panel only has 100 amp tap conductors.
    Rob

    Chief Moderator

    All responses based on the 2011 NEC unless otherwise noted

  7. #7
    Join Date
    Jul 2005
    Location
    Tennessee
    Posts
    12,611
    with each dimmer having it's own OCP and the device is rated at 100 amps, it seems you have met the criteria of 240.21(B)(1)
    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.

  8. #8
    You might have satisfied the tap rule, but are you adequately protecting the dimmer panel? Likewise, how are you ensuring the dimmer panel loads will not exceed 100A?

    I think you need a breaker.

  9. #9
    Join Date
    Jul 2003
    Location
    New Jersey
    Posts
    19,123
    Quote Originally Posted by IslandSparky View Post
    You might have satisfied the tap rule, but are you adequately protecting the dimmer panel? Likewise, how are you ensuring the dimmer panel loads will not exceed 100A?

    I think you need a breaker.
    Well I thought so too until I re-read the 10' tap rule. IMO the installation complies as is without an OCPD at the end of the tap conductors.
    Rob

    Chief Moderator

    All responses based on the 2011 NEC unless otherwise noted

  10. #10
    Join Date
    Jan 2008
    Location
    Southern Maine
    Posts
    374

    Can you put an OCPD

    Just wonder if the install will not allow for an ocpd, if it does and it doesnt break the bank maybe add it....might make you feel better..

Posting Permissions

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