System Sensor Visible Signaling in Large Spaces

June 20 2006 Paper Solving Signaling in Large Spaces Signaling in Large Spaces Overview re alarm system designers including engineers and dealers of cation appliances strobes in retail occupancies warehouses super etc have voiced questions or concerns about the correct spacing candela settings of strobes in retail occupancies even though these were installed according to NFPA 72 standards This document the study and recommendation by the Technical Committee on cation Appliances for Fire Alarm Systems that will be printed in Annex of the 2007 edition of NFPA 72 Their recommendation will clarify the requirements of signaling systems in retail occupancies Challenges 72 states that indirect and direct viewing of the light from visible appliances must exist In other words occupants do not need see a strobe directly to be alerted but merely see its effects such as ections off walls and furnishings However the testing that led to requirement was done in areas with lighting levels far below those in retail occupancies This means that the signal to noise ratio the from the strobe compared with the illumination of the space the strobe in retail is much lower thereby reducing the effect of signaling Because of this some Authorities Having Jurisdiction require strobe coverage in excess of the prescriptive tables outlined NFPA 72 the re protection community is so large and widespread and requirements and recommendations are continually changing technical developments is dif cult purpose of this document is to inform re alarm system designers of recommendation by the Technical Committee on Noti cation Appliances Fire Alarm Systems that will be printed in Annex A of the 2007 edition NFPA 72 for Designing Signaling Systems in Retail Occupancies the 2007 edition of NFPA 72 a recommendation by the Technical Committee Noti cation Appliances for Fire Alarm Systems will be printed in Annex that clari es several factors affecting the design of signaling systems in occupancies particularly big box retail stores such as Wal Mart and Home Depot higher levels of in retail the effect of signals the 2007 edition of 72 Annex A will how the design of systems affect occupancies Sensor Advanced Ideas Advanced Solutions 72 chapter 7 still produce effects the 2007 edition of 72 Annex A will placing strobes over aisles spots are not of concern Signaling in Large Spaces the basis for the recommendations a study was sponsored by the Fire Research Foundation The tests were designed and conducted R P Schi liti Associates Inc with assistance and donations of time and from several other organizations study concluded the higher illumination therefore lower signal to noise ratio in retail occupancies there are still measurable effects due to both and indirect signaling when the prescriptive tables in NFPA 72 7 are used to design the system This means that using the will produce suf cient noti cation This conclusion is derived multiple tests completed by volunteer participants during normal hours in three separate stores cation is more noticeable if the strobes are located directly over the However in retail this may not be practical in stores where the locations are likely to change In most stores there are areas that do tend to change such as main aisles and areas near the cashiers Annex will recommend that strobes be placed directly over these areas stores have blind spots areas with little or no effect from the strobes blind spots are not of great concern to committee members there are redundant methods for occupant noti cation For non hearing impaired individuals are able to hear sounders voice evacuation messages Also retail store occupants tend to be and are likely to move into a position where they can see direct indirect effects from a strobe Stores usually provide multiple egress at any given location and do not have any ends that would an occupant on these conclusions the Technical Committee on Noti cation for Fire Alarm Systems recommends several avenues for further such as the effect of mounting strobes in corridors higher than the 80 inches to 96 inches a reliable signal to noise ratio threshold for occupant cation the effect of ceiling clutter on the ability of a system to alert on back Sensor Advanced Ideas Advanced Solutions Signaling in Large Spaces addition in Annex A of NFPA 72 is part of the committee ongoing effort to further increase integrity of the code recommendations by backing them with reputable research NFPA 72 will to be enhanced in the future as more studies are completed more information please contact Sensor Ohio Avenue Charles Illinois 60174 1 800 sensor2 6 06 1672 Sensor Advanced Ideas Advanced Solutions