National Electrical Installation Standards

Standards as High as Your Own

Friday, January 11, 2019


On a 100 temporary service is the neutral required to be insulated? I have been using SEU cable but the inspector red tagged. His comment was if I could show him in the code book if the neutral was not required to be insulated he would ok the service

Alfred Boggess



Hey Alfred thanks for your question. The general rule is for service entrance conductors to be insulated as stated in 230.41. The exception allows grounded conductors to be uninsulated such as bare copper in list item (1) if part of a service cable assembly and aluminum, without insulation or covering, in list item (4) if part of a cable assembly. SEU cable is commonly used for this purpose. Usually it is the AHJ's responsibility to cite the section that is being violated but at least you inspector is open to reason.

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: