Standards as High as Your Own
NECA Online Help Desk Please leave a message
Charlie, The 2017 NEC code reference at 501.15(C)(3) for sealing and drainage of Class I, Division 1 and 2 installations tells the user of the Code that the thickness of the sealing compound installed in completed seals, other than listed cable sealing fittings, shall not be less than the metric designator (trade size) of the sealing fitting expressed in the units of measurement employed; however, in no case shall the thickness of the compound be less than 16 mm (5∕8 in.).
This language seems to be telling the installer and inspector that for a 19 mm (¾ in) seal off fitting the sealing compound shall be ¾” but in no case less than 5/8 in. Therefore, is a 5/8 in. installation of sealing compound meet the intent of this code requirement? If not, can you explain the intent of this language?
Hey Adolphe thanks for your question, your name seems vaguely familiar, do you have a mustache?
There are two concepts to the rule in 501.15(C)(3). One - the sailing compound thickness must be not less than the trade diameter of the sealing fitting so for a 2-inch sealing fitting the compound must be 2 inches thick. The sealing compound also cannot be less than 5/8 inch so that would need to be the minimum thickness for a 1/2-inch sealing fitting.
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: email@example.com.
© 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.