ADAAG Manual

Location and Spacing

Rooms with an area than can be circumscribed by a circle 50 feet in radius can be covered by a single centrally located strobe of 75 cd. For very small rooms, such as examination, toilet, and dressing rooms, a single strobe of lesser intensity may well be sufficient as an equivalent facilitation.

Recommendations: In general, it is recommended that lamp intensity and spacing be maximized to allow the minimum number of fixtures within a room or space. Large high-ceilinged spaces may be best served by suspended flash tubes of very high intensity. (Lamps up to 1000 cd are available for such applications). Specifiers may be motivated to standardize on a minimum-candela fixture because they are less expensive to purchase and connect, more available, and simplify inventorying. This can lead to close spacing of low-intensity lamps, which is discouraged because of the effect of composite flashes on people with photosensitivity. It may be possible to serve some large rooms or corridor sections with a single appliance located on a perimeter wall or suspended below the ceiling so that the signal can spread throughout the space without obstruction by furnishings, equipment, or room geometry.

Provisions for the spacing of visual alarms in hallways and corridors generally require one fixture every 100 feet. Recommendations: In long corridors, such as in shopping malls and airport terminals, appliances should be spaced to minimize their number and the effect of a composite flash rate. Alternate placement between opposing corridor walls is recommended in minimizing the number of signals in a field of view. Particular care should be taken in locating lamps along window or storefront glazing that may intensify the flash rate due to reflection.