In a remote station fire alarm system, the minimum allowable operating voltage for a notification appliance is down to what percent of its nameplate input voltage?

• A. 85%
• B. 70%
• C. 90%
• D. 75%

Answer: (A)

Voltage tolerance and reliability of notification appliances in fire alarm circuits are about ensuring the device still operates even when the supply voltage drops along long wiring runs or due to regulator variations. For a remote station fire alarm system, the appliance must function down to a specified minimum percent of its nameplate input voltage. That minimum is 85%, which provides a practical margin for voltage drop and component tolerances while still guaranteeing audible/visible signaling.

So, if the nameplate input is 24 volts, the device should work at about 20.4 volts or higher. Values like 70% or 75% would be too low and risk failure to operate; 90% is above the minimum, but the question asks for the lowest acceptable threshold.