National Electrical Installation Standards

Standards as High as Your Own

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Friday, August 9, 2019

Question:

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
A

Answer:

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.

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