breaker size for sub panel

[tmason]

i have a sub panel square d homeline 100 amp if i run number 4 thhn wire rated at 90 c what size breaker would i need

 

[Dennis Alwon]

i have a sub panel square d homeline 100 amp if i run number 4 thhn wire rated at 90 c what size breaker would i need

Assuming this is not nm cable or se cable and the feeder does not carry the entire load of the dwelling- if it is a dwelling then I would say 90 amps if the calculated load is 85 amps or less. 240.4(B)

 

[augie47]

check the answers in this thread where you posted:
http://forums.mikeholt.com/showthread.php/134284-Using-60-degree-ampacity-for-less-than-100A