Emergency lighting requirements specify illumination and duration when normal power is interrupted?

Emergency lighting requirements specify illumination and duration when normal power is interrupted?

• A. 0.5 foot-candle for 60 minutes
• B. 2 foot-candles for 180 minutes
• C. 1 foot-candle for 30 minutes
• D. 1 foot-candle for 90 minutes

Answer: (D)

Emergency lighting is meant to keep exit paths visible so people can evacuate safely when normal power fails. The standard requires at least 1 foot-candle of illumination measured at the floor along the means of egress, and this level must be maintained for a minimum of 90 minutes after power loss. The option that matches these requirements is 1 foot-candle for 90 minutes. The other choices either provide less light (0.5 foot-candle) or shorter duration (60 minutes or 30 minutes), or exceed the standard by offering brighter light for longer (2 foot-candles for 180 minutes), which isn’t the typical requirement for ordinary occupancies.

Emergency lighting is meant to keep exit paths visible so people can evacuate safely when normal power fails. The standard requires at least 1 foot-candle of illumination measured at the floor along the means of egress, and this level must be maintained for a minimum of 90 minutes after power loss. The option that matches these requirements is 1 foot-candle for 90 minutes. The other choices either provide less light (0.5 foot-candle) or shorter duration (60 minutes or 30 minutes), or exceed the standard by offering brighter light for longer (2 foot-candles for 180 minutes), which isn’t the typical requirement for ordinary occupancies.