Are exit signs required to have battery backups?

Exit signs in public, commercial and industrial locations must have a back-up means of remaining illuminated should the power fail. Most signs meet this requirement with a back-up power supply, such as a battery.

.

There are special exit signs that use phosphorescence (photoluminescent) material (glow in the dark) that remains illuminated for a short time after a power failure.

Also, some occupancies are not required to have "emergency lighting", perhaps because they are small enough to safely evacuate without lights, and exit signs in such an occupancy are not required to have any backup power at all.

.

So, technically, no, not all exit signs are required to have a battery backup. You might want to consult NFPA 101 "Life safety Code" at the library for all the details on exit sign lighting, as well as exit illumination. NFPA 101: 7.10.4, for example, any required emergency lighting must to last for at least 90 minutes, and it must illuminate the exit signs that are not photoluminescent, but not every occupancy requires emergency lighting, let alone backup, or lighted exit signs.