National Electrical Installation Standards

Standards as High as Your Own

Friday, August 9, 2019


Double tapping at ground and neutral wires on bus bars in main electric panel. if all houses in this subdivision were built at the same time under same code why when you try to sell your home it would be flagged by an inspector as needing to be fixed.

Janet Blume


Hey Janet thanks for your question. By double tapping I'm guessing you mean having a grounded (neutral) conductor and an equipment grounding conductor in the same termination hole within the panelboard. The rule that required grounded conductors terminate in a terminal that was used for no other conductor was added to the 2002 NEC in 408.21 (now 408.41). Substantiation for the change in ROP 9- 113 stated that this was a " long standing product standard requirement" included in manufacturers installations instructions that are enforceable as stated in 110.3(B) but needed to be in the NEC.

You don't mention when the houses were built or if all of them have that same condition. Different contractors and different inspectors could have resulted in different installations. Either way, if the panelboard manufacturer had that requirement in their instructions, it needed to be followed regardless of whether it was in the NEC or not. This inspector might be aware of that and about problems being caused by that previous practice so hopefully it is being enforced consistently.

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

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.