table 310.15(B)(16) formerly 310.16 shows 90A for allowable ampacity. 230.42A says service entrance conductors shall have ampacity of not less than the maximum load to be served. loads shall be determined in accordance...and so on. as long as load requirements work out with wire ampacity #2 ser is legal to use for a 100A service correct? I have very little experience in residential work, but am sure ive seen plenty of 100A services with #2 SER. i can say it would not be acceptable to feed a 100A subpanel with a 100A breaker and use #2. Im having a hard time finding anything concrete on service entrance conductors. Thanks for any input.