I used 100 amp underground feeder cable to supply transfer switch on a whole house generator. The neutral conductor and grounded conductor are #4 al. The inspector says that they need to be rated same amperage as the power conductors. Is this a code violation? I'm in Virginia.

  • 4
    If your AHJ says you have to do it a certain way, you probably need to do it that way. You might be able to ask the AHJ to explain their logic though.
    – KMJ
    Nov 16 at 18:55
  • I tweaked the description of the various conductors. Please feel free to roll back or edit if I didn't grasp what you were asking, Nov 16 at 19:03
  • 2
    @Triplefault you can size down neutral in some cases, it's super common for mobile home feeders to be 2-2-4-6 for example.
    – KMJ
    Nov 16 at 19:22
  • 1
    Sometimes an AHJ imposes a correct requirement but gives a wrong reason. Maybe it has nothing to do with "generator loads always considered unbalanced" and instead is just "there's a list of scenarios in which that's allowed, and this isn't on the list." See a related answer (there)[diy.stackexchange.com/a/130691/45928] Also, the question says "neutral and grounded conductor" -- it's obnoxious, but neutral is the grounded conductor. Maybe you meant to write 'grounding' conductor. The intent of your question is clear, in any case.
    – Greg Hill
    Nov 16 at 20:10
  • 1
    @keshlam Mostly the pure 240V circuits with no neutral at all (water heating, EV charging, etc.) or with minimal 120V component (dryer, oven, etc.). The reality is that for almost all homes when using more than 65A (ampacity limit for 4 AWG AL 75C) it is extremely likely that the vast majority is 240V balanced (or very nearly balanced, like oven or dryer) loads. But it is a code/AHJ decision and not yours to make. Nov 16 at 21:23


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Browse other questions tagged or ask your own question.