How long do emergency lights last?
Two different questions: how long they stay on in a power outage, and how many years they last before replacement.
During a power outage: at least 90 minutes
Codes require emergency lights and illuminated exit signs to stay on for at least 90 minutes (1.5 hours) after normal power fails. That is the minimum the annual 90-minute test verifies. A unit that cannot reach 90 minutes is out of compliance even if it lights up.
Battery lifespan: a few years
The battery is the part that wears out first. Many emergency light batteries need replacement every few years, sooner in hot locations. See emergency light batteries.
Fixture lifespan: much longer
LED lamps last far longer than the batteries that power them, so a well-made LED unit usually outlives several batteries. Units that are hard to test or service tend to be replaced early simply because they were neglected.
How to get the most life out of them
- Test monthly and annually so weak batteries are found early
- Keep units out of extreme heat where possible
- Replace batteries with the exact specified part
- Use self-testing units so tests actually happen
Frequently asked questions
How long do emergency lights stay on when the power goes out?
At least 90 minutes, as required by code.
How often should emergency lights be replaced?
Replace batteries when they fail the annual test or show a fault; replace fixtures when they are damaged, obsolete or repeatedly failing.