Does table 310.15 B6 allow #2 Aluminum SER cable to be protected by a 100 amp breaker to feed a subpanel? (common practice around here) By "subpanel", I mean a panel that is fed from the panel that contains the main disconnect.
I can't figure out if this table only applies to feeders between the main disconnect(s) and panelboard(s), or all feeders in a dwelling.
Feeder: "All circuit conductors between the service equipment....and the final branch circuit overcurrent device." (NFPA 70, 2002 Article 100 definition)
I, like Bob, think the "main power feeder" must originate at the service equipment and end at a lighting and appliance panel. If you had a 200 amp panel (outside service equipment), it would be legal to feed an indoor panel with 4/0 AL, but it would be a violation to leave the interior panel and feed another panel with 2 AWG (unless the terminals were rated 75 degrees and you use the round-up rule). Once you have a feeder that originates outside of the service equipment, you are in the land of 310.16, not 310.15(B)(6).
You can not round up 90 amp rated 2 AWG AL to 100 amps as 90 amps is a standard size OCPD.
I didn't even look at 240.6, just assuming that 90 is an off the wall number and wouldn't be considered standard. One of these days I'm gonna stop shooting from the lip and start looking in the code before I post :0