View this email as a Web page Please add Code Watch to your Safe Sender list.

October 25, 2006 A Prism Business Media Publication Vol. IV No. 20



CONTENTS
250.32 Buildings or Structures Supplied by a Feeder or Branch Circuit

What's Wrong Here?

Code Q&A

Code Quiz

Code Quiz Correction

Code Committee Call-Up


About this Newsletter
This twice-a-month
e-newsletter is brought to you from the publisher of EC&M magazine.

CodeWatch will:

  • Let you know what could be changing in the Code®.
  • Help you brush up on your ability to apply the Code®.
  • Test your knowledge of the Code® with a Q&A format.
  • Provide information on upcoming Code® seminars and shows.
  • Give you an opportunity to sound off on Code®-related issues.

    We want to make sure we're providing you with the content you need to better manage your business or enhance your technical skills. E-mail us and let us know what you want to see in future issues of this e-newsletter. We will do our best to address your request in a future issue of CodeWatch.


  • Subscriptions
    To unsubscribe from this newsletter go to: Unsubscribe

    To subscribe to this newsletter, go to: Subscribe

    To get this newsletter in a different format (Text or HTML), or to change your e-mail address, please visit your profile page to change your delivery preferences.


    Back Issues
    Missed an issue? Visit the CodeWatch archive on EC&M's Web site.

    Tell a friend about CodeWatch
    Do you know of someone who'd like to receive CodeWatch? Visit the subscriber site, enter their e-mail address and spread the wealth!


    Advertising
    To find out how to advertise in this newsletter, e-mail David Miller or call him at (312) 840-8497.

    The designations "National Electrical Code” and “NEC” refer to the National Electrical Code®, which is a registered trademark of the National Fire Protection Association.

     
    ADVERTISEMENT



    ADVERTISEMENT




    ADVERTISEMENT


    Top 50 NEC Rules



















    250.32 Buildings or Structures Supplied by a Feeder or Branch Circuit

    By Mike Holt
    (A) Grounding Electrode. To provide a path to earth for lightning, each building or structure must have its disconnecting means [225.31] grounded (earthed) to one of the following electrodes [250.50 and 250.52(A)]:
    • Underground metal water pipe [250.52(A)(1)]
    • Metal frame of the building or structure [250.52(A)(2)]
    • Concrete-encased steel [250(A)(3)]
    • Ground ring [250.52(A)(4)]
    Where none of the above grounding electrodes are available at a building or structure, then one or more of the following must be used:
    • Ground rod [250.52(A)(5)]
    • Metal underground systems [250.52(A)(7)]
    Exception: A grounding electrode isn't required where only one branch circuit serves the building or structure. For the purpose of this section, a multiwire branch circuit is considered to be a single branch circuit.

    Bonding Requirements. To quickly clear a ground fault and remove dangerous voltage from metal parts, the building or structure disconnecting means must be grounded (bonded) to an effective ground-fault current path in accordance with (1) or (2) [250.4(A)(3)].

    (1) Equipment Grounding (Bonding) Conductor. The building or structure disconnecting means can be bonded to an equipment grounding (bonding) conductor, as described in 250.118, installed with the feeder conductors. The equipment grounding (bonding) conductor, if of the wire type, must be sized in accordance with 250.122, based on the rating of the feeder protection device.

    Caution: To prevent dangerous objectionable current from flowing onto metal parts of the electrical installation, as well as metal piping and structural steel [250.6(A)], a building or structure disconnecting means supplied by a feeder must not have the grounded neutral conductor bonded to the building or structure disconnecting means.

    Click here to read the rest of this article.

    Editor's note: This information was extracted from Mike Holt's textbook, Understanding the National Electrical Code.



    ADVERTISEMENT
    Fluke 1735 Three-Phase Power Logger
    Power quality logging, electrical load studies and energy consumption testing. The Fluke 1735 Power Logger is the ideal electrician or technician's power meter for conducting energy studies and basic power quality logging. Set the Power Logger up in seconds with the included flexible current probes and color display. The power quality meter measures most electrical power parameters, harmonics, and captures voltage events. www.fluke.com/1735Codewatch


    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: Was this installer color blind?


    Code Q&A
    By Mike Holt
    Q. Do I have to use bonding jumpers around listed reducing washers?

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


    Code Quiz
    By Steven Owen
    Q. What is the proper size overload, and branch-circuit, short-circuit, ground-fault protective device permitted for a hermetic compressor with a nameplate rated-load of 38A, and a branch-circuit selection current of 40A? The fusible disconnect is going to serve as the disconnecting means, the overload protective device, and the branch-circuit, short-circuit, ground-fault protective device. A) 47.5A
    B) 50A
    C) 70A
    D) 90A

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


    Code Quiz Correction
    By Steven Owen
    Although the answer to the question in the last issue was correctly shown as: C) 70A, the ampere ratings in the question were inadvertently reversed. The nameplate rated-load current should have been shown as 38A, and the branch-circuit selection current should have been listed as 40A.

    We apologize for any confusion this may have caused.


    ADVERTISEMENT
    Eliminate the tedium of power system design and analysis! ESA announces the release of EasyPower 8.0 with one touch automated design and one touch automated protective device coordination options available! What used to take hours -- weeks even -- now takes mere seconds! EasyPower delivers a full lineup of Windows® -based tools for designing, analyzing, and monitoring electrical power systems.
    www.easypower.com/?source=codewatch0906


    Code News Update
    Code Committee Call-Up
    Got some extra time on your hands? Looking to put some of your vast knowledge of the electrical field to use? NFPA is looking for new members for several of its committees, including the following:
    • Committee on Electrical Equipment in Chemical Atmospheres. This committee is responsible for NFPA 496, Standard for Purged and Pressurized Enclosures for Electrical Equipment; NFPA 497, Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas; and NFPA 499, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas
    • Committee on Electrical Systems Maintenance (special experts excluded). This committee is responsible for NFPA 73, Electrical Inspection Code for Existing Dwellings.
    Anyone interested in serving can download the application form at NFPA's Web site.



    ADVERTISEMENT
    Cool Electronic Cabinets
    EXAIR's low cost Cabinet Coolers stop electronic control downtime due to heat, dirt and moisture. UL Listed Cabinet Coolers produce 20 degree Fahrenheit air from an ordinary supply of compressed air to cool electrical controls. Thermostat control minimizes air usage. Maintains the NEMA 4, 4X (stainless steel) and 12 rating of the enclosure. Web site offers detailed information, downloadable drawings and PDF literature.
    www.exair.com/15/540_10b.htm


    Shows and Events
    Visit the 2006 EC&M E-TradeShow, a Year-Long Virtual Business Event

    Don't miss these scheduled seminars on November 16 in the EC&M e-TradeShow:
    • "Energy Storage Methods for Electric Power Systems," presented by John DeDad (11:00 a.m. EDT and PDT). Learn about all the new energy storage technologies now available, including ultracapacitors, fuel cells, and flywheels by attending this live conference.
    • Find out how to size residential electrical generators by sitting in on Generac's live conference scheduled for 9 a.m. EDT and PDT. If you can't make these times, catch a special contractor's night live conference at 8 p.m. EDT.
    • If you're looking for information to include in your business forecast for 2007, you'll certainly want to attend the 2007 electrical market sales forecast, presented by Jim Lucy, Electrical Wholesaling's chief editor and scheduled for 10 a.m. EDT and PDT. You'll see forecasting statistics for residential, commercial, institutional, and industrial construction market segments. This yearly presentation has become a MUST for electrical equipment manufacturers, contractors, distributors, and engineers.
    Before attending these events, make sure you visit the 2006 EC&M e-TradeShow, a year-long virtual business event. In addition to attending live activities at conference sessions scheduled throughout the year, you can meet with exhibitors in virtual exhibit halls. You can also access past presentations that are archived in the e-Tradeshow. Employing the latest interactive 3D technology, sponsors use online trade-show booths to generate leads on a continuous basis throughout the year, while interacting live with customers and prospects during scheduled events. Free access and all the information you need are available at the event's Web site.




    ADVERTISEMENT
    One Gets It Done.
    Feel the difference with the Twister® Wire Connector. A comfortable swept wing design provides added leverage, while the durable polypropylene shell expands for a smooth application. The patented live-action, square-wire spring locks onto the wire for safe, secure connections. Don't settle for just any wire connector. Insist on the Twister. Visit www.idealindustries.com for a free sample.


    You are subscribed to this newsletter as #email#

    For questions concerning delivery of this newsletter, please contact our Customer Service Department at:
    Customer Service Department
    EC&M
    A Prism Business Media publication
    US Toll Free: 866-505-7173
    International: 847-763-9504
    Email:ecmweb@pbinews.com

    Prism Business Media
    9800 Metcalf Avenue
    Overland Park, KS 66212

    Copyright 2006, Prism Business Media. All rights reserved. This article is protected by United States copyright and other intellectual property laws and may not be reproduced, rewritten, distributed, re-disseminated, transmitted, displayed, published or broadcast, directly or indirectly, in any medium without the prior written permission of Prism Business Media.