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Wednesday, October 21, 1998
Question:
What is the smallest size copper ungrounded service entrance conductor permitted by the NEC?
A #14
B #12
C 60A
D 100A
A
Answer:
Section 230-42(b) exc. 3 states 'For limited loads of a single branch circuit, No. 12 copper ... but in no case smaller than the branch-circuit conductors.' Along the same line, section 230-79(a) says the smallest service disconnecting means is 15 amperes and section 230-90(a) says to protect the service entrance conductors at their ampacity. Therefore, you can install a 15 ampere service to serve a single circuit limited load but it has to have #12 Cu. or #10 Al. Service entrance conductors.