A surge-protection device on a feeder is required in all of the following locations except for which?

• A. Dwelling units
• B. Operating rooms
• C. Dormitories
• D. Guest suites of motels

Answer: (B)

Surge protection devices on a feeder guard downstream equipment from voltage spikes and transients coming from the utility or lightning. In many occupancies, like dwelling units, dormitories, and guest suites, protecting the feeder helps shield the numerous connected loads and sensitive electronics in those spaces. Operating rooms, however, sit within a hospital’s essential electrical system with highly controlled power quality, isolation, and backup power (often UPS-backed) for critical medical equipment. Adding a feeder SPD in that environment can interfere with or complicate this critical-power setup, so the code does not require it there. That’s why operating rooms are the exception.