Notification Appliances
Strobes, horns, candela ratings, synchronization, ADA compliance, sound level requirements, and NAC sync protocols.
- State the minimum candela ratings for wall-mount and ceiling-mount strobes
- Explain ADA-compliant sound level requirements for notification appliances
- Describe strobe synchronization requirements and why they matter
- Identify silenceable and non-silenceable notification circuits
- Calculate basic notification appliance coverage using candela tables
Lección 1
Horns, Strobes & Candela Ratings
Notification Appliance Types
Notification appliances alert building occupants to a fire alarm condition. The two primary types are:
- Audible appliances - horns, speakers, bells, chimes
- Visual appliances - strobes (required for hearing-impaired persons per ADA)
Most modern installations use horn/strobe combination units that provide both audible and visual notification in a single device.
Candela Ratings
Strobe intensity is measured in candela (cd) and must be selected based on room size. NFPA 72 Table 18.5.5.5.1(a) provides candela requirements for wall-mounted strobes:
| Room Size (max dimension) | Wall-Mount Candela |
|---|---|
| 20 x 20 ft | 15 cd |
| 28 x 28 ft | 30 cd |
| 40 x 40 ft | 75 cd |
| 45 x 45 ft | 110 cd |
| 50 x 50 ft | 177 cd |
| 54 x 54 ft | 185 cd |
Exam Tip - Candela Tables
The NICET exam will provide candela tables. You must know how to use them - match the maximum room dimension to the required candela. When a room exceeds the table maximum for a single strobe, add additional strobes.
Wall vs. Ceiling Mount
Ceiling-mounted strobes have different candela requirements than wall-mounted units. Ceiling strobes distribute light downward in a circular pattern, so the candela tables are based on the maximum room area rather than the longest wall dimension.
Strobe candela must be selected from NFPA 72 tables based on room size. Wall-mount tables use the maximum room dimension, while ceiling-mount tables use room area. Minimum wall-mount candela for a 20x20 room is 15 cd.