I'm looking to control several channels of AC power and a triac looks to be a good option. My question is if a sensitive gate triac can be driven directly from the arduino output? This is just going to be for on/off, I will not be doing any dimming or power control. The max draw will never reach even 500ma so a triac seems like the best small/option to me.
Yes you can drive it through an opto isolator. Without synchronising the signal with the zero crossing point on the mains cycle you get more interference generated Evan at half an amp.