Is it possible to wear regular and Power Armor at the same time? In case one needs to leave the Power Armor, are you then defenseless?
p.203 "The cockpit of powered armor is too small to fit a person wearing heavy armor."
You can wear light armor inside your powered armor though, in which case you get whichever KAC and EAC is better between the light and powered armor, but have to take the *worst* Armor Check Penalty.