System Sensor has developed the Equivalent Facilitation Web-based calculator in an effort to provide architects and engineers with easy access to a tool that will assist in the design of audible/visible notification device circuits. By visiting www.systemsensor.com and then selecting the Install/Specify System Sensor Products tab or going directly to systemsensor.com/equivalent_facilitation/index.html, visitors are able to perform notification circuit design calculations by entering ceiling strobe candela values and inputting the longest wall and the ceiling height of the room. This calculator uses data provided by the user to perform the calculations described in Chapter 7 of the 2002 edition of NFPA 72, which permits the use of a performance-based alternative in lieu of tables for spacing ceiling-mounted audible/visible devices. System Sensor.