An emergency battery backup fixture is a normal LED fixture with a battery pack built in or added on. When power fails, the battery keeps the fixture lit at reduced output for at least 90 minutes, which is the runtime the Life Safety Code calls for. It lets one fixture do the job of a regular light and an emergency light.
What the code asks for
NFPA 101, the Life Safety Code, sets the baseline most jurisdictions adopt for emergency lighting along the path of egress:
- Runtime of at least 90 minutes after normal power fails.
- Light level of an average of 1 foot-candle at the start, and no less than 0.1 foot-candle at any point along the path.
- Allowed decline to an average of 0.6 foot-candle and a minimum of 0.06 at the end of the 90 minutes.
- Testing with a 30 second functional test every month and a full 90 minute test every year, with records kept.
Your local code and fire marshal have the final say, so check what your jurisdiction has adopted.
How the battery pack works
The pack charges from an unswitched hot conductor, so it stays charged even when the wall switch is off. When the pack senses that power is gone, it drives the LEDs at a reduced level, usually listed on the spec sheet in emergency lumens or emergency watts. A test switch and charging indicator are mounted where you can see and reach them.
The wiring detail people miss: run an unswitched hot to the pack. If the pack is fed from the switched leg, it reads every time someone turns the lights off as a power outage and drains its battery.
Built in battery vs separate emergency lights
| Option | Good for |
|---|---|
| Fixture with battery backup | Corridors, stairwells and open offices where you want clean ceilings and fewer devices. |
| Separate emergency units (bug eyes) | Retrofits where you are not replacing the fixtures, and back of house areas. |
| Exit and emergency combos | Exits where you need the sign and the egress lighting in one unit. |
Cold spaces and battery life
Batteries do not like cold. If the fixture is going into an unheated warehouse, a cooler or an outdoor canopy, check the pack's rated temperature range. Plan to replace packs as they age, since batteries lose capacity over the years. The annual 90 minute test is what tells you a pack is getting weak.
Common questions
How long does emergency lighting have to stay on?
NFPA 101 calls for emergency lighting to operate for at least 90 minutes after normal power fails.
Does an emergency battery backup need an unswitched hot?
Yes. The pack needs constant power to stay charged. Feeding it from the switched leg makes it treat every switch off as an outage.
How often do emergency lights need to be tested?
Under NFPA 101, a 30 second test every month and a full 90 minute test once a year, with written records.
Shop fixtures with battery backup and exit and emergency lights. Related: exit signs and emergency lighting requirements. Questions? Contact us or call 845-681-2684.
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