I'm remodeling my basement and just got an electrical permit. The inspector told me that lighting fixtures can't be mixed with general outlets on a 20A breaker circuit, but they can on a 15A circuit. I asked why, and he said "light fixtures aren't rated for 20A and must be on 15A (MAX) breaker.

Question - Does the code actually specify this and if so, why ? The 5A difference before the breakers trip doesn't seem to be significant. Anyway, all kinds of devices will get plugged in to the 20A circuit outlets - many of which I'm sure couldn't take even 15Amps w/o damage.

I already have 20A breakers - and would like a reason why I need 15A breakers. Thanks.

Unfortunately, the local building codes supersede any national standard so you are going to have to live by his ruling. Lighting fixtures should never be mixed with outlet fixtures since the current draw will have an adverse effect on the lights (ex: running a vacuum cleaner will dim the lights considerably).