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Friday, April 30, 2021
Question:
Hello Code Question of the Day.
Thanks for the great information. What is the minimum conduit size for an 80-ampere, 3-phase circuit circuit?
Charles Smith
A
Answer:
Hi Charles,
The response to your questions is based on the information provided. There is information missing such as the type of conduit or tubing, ambient temperature and location where the conduit is installed, type of conductor insulation, etc. Based on the Tables of the NEC (Specifically Table 310.16 and Table 1, Chapter 9). Table 310.16 indicates a 3 AWG copper conductor (Type TW) is good for 85 amperes with no ampacity adjustments or correction factors or applied. So (3) 3 AWG conductors would require a minimum 1/2 inch looking at Table C9. This response does not address any associated equipment grounding conductor that may also be required in the conduit.