?
Thursday, December 17, 2020
Question:
Dear Code Question of the Day,
What is the smallest size ungrounded service conductor I can install for a single dwelling unit that requires a 100-ampere 120/240-volt, single-phase service?
Alvin Harper
A
Answer:
Hi Alvin,
Thanks for participating. The NEC does provide a minimum size copper conductor for the installation described. Section 310.12(B) and Table 310.12 would permit not smaller than a 4 AWG copper ungrounded service conductor as the minimum for the service described. The question is based on the 2020 NEC. The answer is the same if based on 2017 except that the Code Section is 310.15(B)(7) except that the table is not used, but an 83% multiplier is used and based on the service rating.