The proper amount of illumination for an emergency lighting system must be provided for:

• A. 30 minutes
• B. 60 minutes
• C. 90 minutes
• D. 120 minutes

Answer: (C)

Emergency lighting is meant to keep exit paths visible when the normal power fails, giving occupants enough time to evacuate safely. The standard minimum duration for this illumination is 90 minutes. This length covers the typical time needed to move through corridors and stairwells to a safe area or exit, even in reasonably large or complex spaces. Shorter durations like 30 or 60 minutes may not provide sufficient coverage for every evacuation scenario, while longer durations such as 120 minutes exceed the baseline requirement unless a specific situation calls for it. 90 minutes strikes the balance as the required minimum to ensure safe egress during an outage.