National Electrical Installation Standards

Standards as High as Your Own

?
Friday, December 22, 2017

Question:

What is the proper application of NEC Article 110.14(C)(1)(b)? 110.14(C)(1)(b) reads as follows: "Termination provisions of equipment for circuits rated for over 100 amperes, or marked for conductors greater than 1 AWG, shall be used only for one of the following:" The "or" in this article yields two greatly different results. Based on the first part any device of 100 ampere (110 amps) we use the 75 degree column in Table 310.15 (B) and 2 AWG is sufficient, but the "or" part of the statement requires a 1/0 AWG conductor before we use the 75 degree column in Table 310.15 (B). Under the "or" part of the rule for a 110 amp device we use a 1 AWG under the 60 degree column of Table 310.15(B) and we need to use 1/0 AWG for 125 amp devices; since #1/0 AWG is rated for 125 amperes at 60 degrees C and 1 AWG cannot be rated used for the 75 degrees C. Any clarification on this article is appreciated. Thanks Rick

A

Answer:

Hey Rick thanks for your question, the wording could be improved. The termination device is often part of the equipment such as the terminals of a circuit breaker of fusible switch. If that circuit breaker or fusible switch is rated more than 100 amperes then the temperature rating is 75 degrees C unless listed and marked otherwise. If the termination device does not have an ampere rating then if marked for conductors larger than 1 AWG its temperature rating is 75 degrees C unless listed and marked otherwise.

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. NEISÔ 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: codequestion@necanet.org.