If the C&E overrides manual controls (e.g., silencing alarms or overriding door releases), it can hinder firefighter operations. Good design includes bypass or override provisions.
The Effect was the ionization sensor in the hallway ceiling. It was a cheap, plastic puck of a thing, stained yellow by years of cigarette smoke from the previous tenant. It sat there, dormant and essentially blind, waiting for a specific disruption in the air's density.