National Electrical Installation Standards

Standards as High as Your Own

Friday, December 21, 2018


I have a 240 volt 2 # 6thhn + # 10 gr (3 wire) no neutral hot tub. The hot tub is fed from a spa gfci 60 amp disconnect. The spa 60amp disconnect is fed from the main pnl with 2 # 6 thhn + a 10 gr can I use a # 10 neutral since it is only used on the spa neutral bar so the neutral off the gfci breaker can tie into the main pnl neutral and the gfci breaker will function correctly

Don Sieber



Hey Don thanks for your question. Yes. The minimum feeder neutral conductor size is determined using 220.61 based on the neutral load which in your case is the internal GFCI electronic components. The feeder grounded conductor (also the neutral in your example) must be not smaller than given in 250.122 as stated in 215.2(A)(2). Based on the 60 ampere overcurrent protective device a 10 AWG copper grounded (neutral) conductor in addition to the 10 AWG equipment grounding conductor is acceptable.

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: