Pit Detectors. As in the top of the hoistway, a rate-of-rise heat detector installed within two feet of each sprinkler head is normally used in the elevator pit (F). Note that not every elevator system will have all of the features shown in the illustration. For example, NFPA 13 requires side-wall sprinklers in an elevator pit only if the pit contains combustible hydraulic fluids or the hoistway itself is made of combustible materials.
Additionally, placing the sprinkler heads within two feet of the pit floor removes the requirement for a shunt-trip from these pit sprinklers. If the Alternate Level is the lowest level and the Designated Level is above that, then the pit detector will actuate Circuit #2, not circuit #1.
Greg Kessinger, SET, CFPS, president of an alarm installing company since 1981, teaches NICET training classes to fire alarm system designers and installers and continuing education seminars for Ohio's fire alarm inspectors. You can reach Greg Kessinger at 888-910-2272; e-mail: Greg@firealarm.org; or visit his website at www.FireAlarm.org.