ECN Forum Forums General Topics of the Trade General Discussion Area Staircase Pressurization Fan Motor Overload

Your second question: Thermal OLs 'open', and the motor starter opens (Off).

First question may require more than the NEC, as staircase pressurization is Building & Fire Safety Codes. I suggest that you contact the local AHJs in whatever area you are working in. My opinion would be no OLs, just short circuit protection as this is a life safety item, perhaps like a fire pump. Just my opinion.