Standards as High as Your Own
NECA Online Help Desk Please leave a message
Are enclosures of equipment installed for and supplied by ungrounded A/C systems required to be marked to indicate that? What NEC rule applies.
Thanks for any help you can provide.
Section 250.21(C) indicates that ungrounded systems shall be legibly marked “Caution: Ungrounded System Operating — _____Volts Between Conductors” at the source or first disconnecting means of the system. The marking shall be of sufficient durability to withstand the environment involved.
ABOUT CQD: The Code Question of the Day (CQD) is NECA and ELECTRICAL CONTRACTOR Magazine’s flagship National Electrical Code (NEC®) public forum for the industry, sponsored by EATON. The daily distribution of Q&A generates a lively dialogue and shares relative Code-based practical responses.
SUBMIT YOUR CODE QUESTION: Click here to submit a question to for inclusion in an upcoming edition of the Code Question of the Day, or email email@example.com.
CHARLIE TROUT: 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. Even though Charlie passed away in October of 2015, his work continues in spirit. NECA continues to maintain this question forum for its many subscribers in memory and recognition of all his significant contributions to making the NEC what it is today.
NECA STANDARDS: NECA publishes the National Electrical Installation Standards™ (NEIS™), a series of ANSI-approved performance and quality standards for electrical construction. NEIS can be purchased in the NECA Store in three formats: a printed or PDF download of a standard or, as an annual subscription service.
NECA SAFETY PRODUCTS & PUBLICATIONS: NECA produces electrical safety publications and products for the industry including jobsite safety guides, handbooks and resource kits. View a full listing of available resources and products »
IMPORTANT NOTICE: Unless the question requests a response based on a specific edition, all answers are based on the latest edition of NFPA 70® National Electrical Code®.
This correspondence is not a formal interpretation of the NEC® and any responses expressed to the questions are opinions and do not necessarily represent the official position of NECA, NFPA, the NEC Correlating Committee any Code-making panel or other electrical technical committee. In addition, this correspondence is neither intended, nor should it be relied upon, to provide professional consultation or services.
UPDATE YOUR SUBSCRIPTION PREFERENCES: Subscribe or Unsubscribe from this list.
© 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.