Reference · Design
Candela (cd)
The unit of luminous intensity used to rate visible notification appliances (strobes). NFPA 72 tables give the required candela for a room size and mounting height so occupants with hearing loss are alerted.
NFPA 72: 18.5 (Visible Characteristics), Tables 18.5.5.4.1(a)/(b)
Section numbers vary by edition — confirm in the edition your AHJ has adopted.