Article and photos by Gregory Havel
The ASME and NFPA standards and codes consider the occupants of an elevator car that is stopped between floors or that is evacuated at the nearest floor level to be at less risk than they would be if the elevator continued to operate during fire sprinkler discharge.
3. Arriving firefighters may initiate Phase II Emergency In-car Operation by using a key and pressing buttons inside the elevator car to close and open doors and to move the car between floors. Photo 1 shows a typical lobby elevator control panel with the key switch to select firefighter operation. Photo 2 shows a typical elevator car control panel, with the firefighter key switch and indicator lights in the red panel in the center and operating instructions in red directly above. In this way, firefighters can quickly move equipment to upper floors nearer the location of the fire and evacuate persons who are unable to self-evacuate using stairways.
4. If smoke is present at the top of the elevator hoistway or in the machine room, the smoke detector will activate a circuit in the elevator controller. This will cause the red firefighter helmet indicator light on the control panel (see photos) to begin to flash, indicating that smoke and fire are near the elevator machine or in the hoistway and that a power shunt trip is possible. The instructions on the panel in Photo 2 state, “WHEN [fire helmet] FLASHES, EXIT ELEVATOR.” Firefighters at this time have the choice of manually opening the elevator doors at the nearest floor and exiting the elevator or attempting to return the elevator car to the primary recall floor with the risk of becoming trapped in the elevator between floors when the power shunt trip breaker operates.
5. When significant heat is present at the top of the elevator hoistway or in the machine room, the heat detector near a sprinkler head will sense that sprinkler discharge is imminent and will cause the main elevator power to shunt trip without delay, without any action by the elevator controller. This power shunt trip breaker can only be reset manually in the elevator machine room. Disconnection of the elevator main power does not affect lights or communications with the elevator car, which are on separate circuits.
However, there are two (rare) scenarios in which firefighters or other building occupants could become trapped by a power shunt trip:
- A very slow elevator, or one with a great distance to travel, with a fast-moving fire in or near the elevator machine room. In this instance, the elevator does not have time to complete Phase I recall before the power shunt trip.
- A large-scale incident in a multistory residential building occupied by many persons who are not capable of self-evacuating by way of stairs, which could result in firefighters using the elevator on Phase II operation to the last possible moment to remove as many occupants as possible.
The author acknowledges the valued assistance with the research for this article by Brian Rausch PE, at the Wisconsin Elevator Safety Program of the Wisconsin Department of Commerce.
Gregory Havel is a member of the Burlington (WI) Fire Department; a retired deputy chief and training officer; and a 30-year veteran of the fire service. He is a Wisconsin-certified fire instructor II and fire officer II, an adjunct instructor in fire service programs at Gateway Technical College, and safety director for Scherrer Construction Co., Inc. Havel has a bachelor's degree from St. Norbert College; has more than 30 years of experience in facilities management and building construction; and has presented classes at FDIC.
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Subjects: Building construction for firefighters