Standards as High as Your Own
NECA Online Help Desk Please leave a message
We are removing a 4000 amp 120/208 volt 3 phase bus that runs horizontal in a ceiling, and installing 11 - 4" pvc pipes in the ground with parallel 500 mcm wires. These pipes are after the main service disconnect feeding a MCC. Do I need to pull a 500 mcm ground in each pipe to satisfy 250-122 (F)?
Hey Mike thanks for your question. Yes, the equipment grounding conductors in each raceway need to be sized based on the overcurrent device protecting all of the parallel conductors as stated in 250.122(F). For a 4000 ampere overcurrent device a 500 kcmil copper equipment grounding conductor needs to be installed in each raceway as shown in Table 250.122.
Thank you for the comment! Your comment must be approved first
You've already submitted a review for this item
Thank you! Your review has been submitted successfully
Login to be able to comment
Comment cannot be empty
Rating is required
You typed the code incorrectly. Please try again
ABOUT CQD: NECA’s Code Question of the Day (CQD) is a leading National Electrical Code® forum for NECA and the industry. The CQD generates a lively dialogue and relative practical and Code-based responses to an ever-increasing and interactive audience.
IMPORTANT NOTICE: All answers are based on the latest edition of the National Electrical Code®, unless the question requests a response based on a specific edition. This correspondence is not a formal interpretation of the NEC®. Any responses expressed to the questions are opinions and do not necessarily represent the official position of NECA, NFPA, or any technical committee. In addition, this correspondence is neither intended, nor should it be relied upon, to provide professional consultation or services.
ABOUT CHARLIE: Charles M. Trout, better known as Charlie, was a nationally known NEC® expert and author. He served on several NEC® technical committees and is past chairman of CMP-12. In 2006 Charlie was awarded the prestigious Coggeshall Award for outstanding contributions to the electrical contracting industry, codes and standards development, and technical training. Charlie was also a member of NECA’s Academy of Electrical Contracting. Charlie’s experienced team of industry experts keep the CQD dialogue and discussions active and informative in the spirit of the man himself, as he wanted.
NECA STANDARDS: NECA publishes the National Electrical Installation Standards™ (NEIS™), a series of ANSI-approved performance and quality standards for electrical construction. Visit NECA-NEIS.org for more information. NEISÃ” can be purchased in three formats: as paper books, on CD, or as electronic downloads.
NECA SAFETY PRODUCTS: NECA publishes valuable electrical safety books and CDs for the industry. Visit necanet.org/store to view or purchase NECA safety products.
CONTACT US: To submit a Code question, subscribe, or unsubscribe from this list, please e-mail: firstname.lastname@example.org.
© 1999 – 2014 National Electrical Installation Standards. All rights reserved.
Brought to you by NECA. NECA is the voice of the electrical contracting industry NATIONAL ELECTRICAL INSTALLATION STANDARDS, NEIS and the NEIS logo are registered trademarks of the National Electrical Contractors Association.
Created by Matrix Group International, Inc.