Flashing strobe lights are given an effective intensity expressed in candelas (cd). This measurement can be compared to the light produced by a steady burning light.
What is CD in fire alarm?
The device’s coverage area is dependent on the strobe’s intensity, measured by the listed candela (cd) rating or the luminance flux per solid angle omitted by the strobe. The maximum coverage areas for strobes are listed in NFPA 72 Section18.5 and are based on commonly listed candela ratings.
Where are speaker strobes required?
NFPA 72 requires strobes installed in hallways and corridors to be visible from anywhere. The code states these specific requirements: Strobes must be installed no further than 100 feet apart down the length of a hallway. Strobes must be located within 15 feet of either end of a hallway.
How is candela rating determined?
“Where it is not located in the center of the room, the candela level shall be determined by doubling the distance from the appliance to the farthest wall to obtain the maximum room size.” For Ceiling mount devices over 30 feet, refer to Performance Based-Alternative in 18.5.
Where are visible notification appliances required?
The ADAAG requires visible notification appliances to be mounted at least 80 inches above the finished floor, or six inches below the ceiling, whichever is lower. Section 4-4.4 of NFPA 72 requires visible appliances to be mounted such that the entire lens is between 80 and 96 inches from the finished floor.
Where are fire alarm horns required?
Over the years, it has become customary to install horn strobe over every pull station, which are required every 400 feet on centers or no greater than 200 feet travel, NFPA 101 9.6. 2.5.
Are strobes required in private offices?
1 General stipulates that alarm systems required to be accessible shall provide visible signals in restrooms, in other general and common use areas, and in hallways and lobbies. … Therefore, visual alarms are not required in individual employee offices and work stations.
Are strobes required in offices?
Individual employee work areas such as offices and workstations are not required to have visual strobes, unless accommodating hearing impaired employees and they must contain audible alarms and notifications.
Do fire alarm strobes need to be in sync?
The code requires all strobes that are in one viewing to be synchronized. However, there are exceptions to this requirement. For example, NFPA 72-2010, Section 18.5.
What is private mode signaling?
Private Operating Mode is an audible or visual signaling only to those persons directly concerned with the implementation and direction of emergency action initiation and procedure in the area protected by the fire alarm system.
What is the distance between horn strobes?
The maximum spacing between fire strobes should not exceed 100 feet. All strobes must be located within 15 feet of the end of the corridor. According NFPA 72, Appendix A, the recommended placement for corridor strobe lights indicates that any interruptions in a corridor indicates separate corridors.
How many horn strobes are in a circuit?
NOTE: The total number of strobes on a single NAC must not exceed 40 for 24 volt applications or 12 for 12 volt applications.