National Electrical Installation Standards

Standards as High as Your Own

Wednesday, July 11, 2018


We have a new construction in Boston that uses fire rated construction on the parking level and then builds from there with conventional lumber 3 to 5 floors. My question is regarding type NM cable, can NM cable be run through the parking area and then up to the units above? My inclination says no, type MC cable should be used. Any thoughts?

Stephen McCarthy



Hey Stephen thanks for your question. NM cable is allowed to be installed in structures that are allowed to be of Types III, IV, or V construction (not fire resistant). If the parking area is required to be fire resistant (which is likely why it is of that type) then NM is not permitted. See NEC Annex E and NFPA 220 for more information on building construction types.

Yes, MC cable, or any other suitable wiring method can be used, or in the parking area the NM cable can be installed in raceways as stated in 334.10(5).

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 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 to view or purchase NECA safety products.

 CONTACT US: To submit a Code question, subscribe, or unsubscribe from this list, please e-mail: