Code Applied by the app elec.emergency.battery-duration
Emergency lighting battery duration
How long an emergency lighting source must carry its load with the normal power out, 90 minutes, which is why every exit sign and emergency light on a small job carries a battery.
| When | The app uses |
|---|---|
| emergency lighting and exit signs, light with the power out (battery unit equipment) | 90 min |
- Source
- NEC · 700.12 (unit equipment: 700.12(F) in 2017, (I) in 2020, (H) in 2023) · read the public text
- Editions checked
- 2017 · 2020 · 2023
- Used by
- Courses
- Amendments
No state or local amendment to this rule is on file. Not on file means the model code as written — check your jurisdiction.
A model code the authority having jurisdiction adopts.
When the power goes out, the exit signs and the emergency lights have to keep the way out lit for an hour and a half. On a restaurant that source is almost always a battery in each fixture (unit equipment). Its branch circuit is one of two: the same circuit as the normal lighting in the area, connected ahead of any switch, or a separate circuit from the same panel as the normal lighting, whose breaker has a lock-on so nobody switches it off. The course's restaurant takes the second: circuit 21 on LP-1, with a lock-on.
On a bid that makes the Type X and Type EM fixtures more than a fixture: a battery and a test switch in each, and an unswitched circuit to each one, with the lock-on when it is a circuit of its own. The building code says where the lights go (IBC 1008, its own rule); this rule says how long they must last.
What the app does with it
The electrical course teaches it on a card (Chapter 3, Which rooms switch themselves off?), and check-lesson-rules holds the card's numbers to this rule. The app counts the fixtures you mark; it does not know which are emergency or check their circuit.
Verify against your edition
The 90 minutes (1½ hours) holds in 2017, 2020 and 2023. The unit-equipment paragraph moved letters: 700.12(F) in 2017, (I) in 2020, and in 2023 the battery-equipped luminaire is 700.12(H), which states no duration of its own. In 2017 the separate circuit was only an exception (an area fed by three or more normal lighting circuits); from 2020 it is a plain option, with the lock-on. The 2023 paragraph that states the duration for every source was read only in a secondary summary (as 700.12(C), Supply Duration); read it in a 2023 copy before citing its letter. Local amendments still govern.
Settled 2026-09-27 by Claude on the owner's delegation, from the dossier's research and the model code text; not checked against a printed book or a local amendment. The 2023 duration paragraph is 700.12(C), Supply Duration: two secondary sources agree on the letter and the title (a continuing-education summary, and Electrical Contractor magazine's review of the 2023 changes), and the paragraph itself has not been read in the NEC.
Cited by section, not reprinted: the code text belongs to its publisher. Company practice is not a rule here — it lives with your pricing.