If you don't have water-based fire suppression, have normally unoccupied spaces, and are continuously manned, it's sometimes possible to pass on having an EPO. YMMV by inspector.
That is indeed true, as we were able to have ours disconnected, and were able to expand our facility without adding EPOs in the new datacenter rooms. We were told that since we met a specific list of criteria, which included things like FM200/Ecaro25 fire suppression, solid (not raised) floors, electrical wiring done some particular way, and large signage indicating where the safety hazards lie for our friends in the Tukwila & Seattle Fire Departments... we got a pass on the Big Red Button. I imagine those criteria change from place to place, and time to time... perhaps even inspector to inspector. I sleep better at night. Well... A little bit better. --chuck