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October 26, 2007 A Penton Media Publication Vol. V No. 20

310.15 Conductor Ampacity

What's Wrong Here?

Code Q&A

Code Quiz

EC&M Code Change Conferences

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    Top 50 NEC Rules

    310.15 Conductor Ampacity

    By Mike Holt
    (A) General Requirements
    The ampacity of a conductor can be determined either by using the tables in accordance with 310.15(b), or under engineering supervision as provided in 310.15(C).

    FPN No. 1: Ampacities provided by this section do note take voltage drop into consideration. See 210.19(A) FPN No. 4 for branch circuits and 215.2(D) FPN No. 2 for feeders.

    If a single length of conductor is routed in a manner that two or more ampacity ratings apply to a single conductor length, the lower ampacity must be used for the entire circuit. See 310.15(B).

    Exception: When different ampacities apply to a length of conductor, the higher ampacity is permitted for the entire circuit if the reduced ampacity length does not exceed 10 ft and its length doesn't exceed 10% of the length of the higher ampacity.

    Click here to read the rest of this article.

    No matter where you are in the challenging process of developing or implementing an Arc Flash Safety Program, you can rely on ESA to help. Take advantage of the free resources we offer such as our Arc Flash Book, Arc Flash Specification, 10 Steps of an Effective Arc Flash Hazard Safety Program guide and more.

    Code Challenge

    What's Wrong Here?

    By Joe Tedesco

    Think you know how this installation violates the NEC?

    Visit EC&M's Web site to see the answer.

    Hint: Fill it with ice.

    Code Q&A
    By Mike Holt
    Q. How far away from a diesel fuel-dispensing tank must the nonexplosion-proof equipment be located?

    Visit EC&M's Web site to see the answer.

    Code Quiz
    By Steven Owen
    Q. A new service consisting of six individual disconnect switches has been installed outdoors, on the back side of a small retail shopping center. One of the disconnect switches has been installed remote from the others. The disconnect installed remote from the others is for the water pump intended for fire protection. Is this installation NEC compliant?

    1. Yes, because the disconnect switches can be installed in any location and in any grouping of the installers choice -- no NEC requirement.
    2. Yes, because one of the two to six service disconnecting means is permitted to be installed remote from the others that are grouped together in one location if it meets the requirements of the exception associated with the grouping requirement.
    3. No, because retail shopping locations require that all service disconnects be installed in a locked room in a separate building adjacent to the shopping area.
    4. No, because all service disconnects need to be installed in indoor locations only.

    Visit EC&M's Web site for the answer and explanation.

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    Shows and Events
    EC&M Code Change Conferences
    Where do you turn when you need accurate information on changes to the National Electrical Code? Acknowledged as the leaders in providing information on the NEC, EC&M magazine and EC&M Seminars have been the preferred sources of this information for more than 60 years. Seven Code change conferences have been scheduled in the fall of 2007. Host cities include: Atlanta, Boston, Dallas, Orlando, Philadelphia, St. Louis, and Seattle.

    As an approved provider with the National Council of Examiners for Engineering and Surveying (NCEES), through its Registered Continuing Education provider Program (RCEPP), professional engineers attending any of our 2008 Code change conferences will receive Professional Development Hours (PDHs), a requirement for re-licensing in many states. The conferences are also approved by every state that has a continuing education requirement for contractors and electricians.

    For additional information on the dates and locations of these events, click here.

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