Automatic Fire Alarm Elevator Use.
A couple questions, I am wondering what your SOGs are for elevator use when investigating automatic fire alarms (no signs of smoke of flame)?
Do you put the elevator in fire service mode or ride it up regularly?
Do you take the elevator to a floor below the fire floor, if so, how many floors below the fire floor?
Does anyone have SOG's they would be willing to share on elevator use for auto alarms?
Elevator "Shunt Trip" Circuit Hazards
Please be aware that starting the mid 90s elevators in fully auto sprinklered buildings were constructed with a circuit that electricians call a "shunt trip." The circuit gets it's name from the characteristic that it "shunts", or redirects, some of the current from the circuit breaker supplying power to the elevator circuits to a solenoid located inside the breakers case. That solenoid trips the breaker to the open position. The purpose of the circuit is to insure that the elevator machinery will be de-energized prior to the discharge of water from automatic sprinklers that are located in elevator shafts and machine rooms. Let me emphasize that none of this is effected by what mode of service the elevator is in. In can be under automatic, local control, inspection, and, yes even, fire service control and the shunt trip circuit will still operate. If this should occur while firefighters are in the elevator cab; and that cab is not at a floor landing with it's door open; then the elevator cab becomes a coffin on a tube or a coffin on cables.
The circuit is initiated by heat detectors that are located adjacent to the sprinkler heads located in elevator shafts and machine rooms. The detectors are selected to operate at a lower temperature than the temperature at which the sprinkler head will open and discharge water. Once the shunt trip solenoid is energized there is no way to restore power to the elevator equipment. Any attempt to re-close the circuit breaker will re-energize the solenoid and trip the breaker to the open position immediately.
For the first six years of the rule's application there was no requirement to integrate that circuit with the elevator's fire alarm recall system. The earliest version of this circuit provided no warning of any kind prior to the operation of the circuit. When one of the heat detectors operates all power to the elevators is lost. Thousands of elevators were constructed under that first version of the shunt trip rule.
The second version of the rule required that the circuit had to include delayed operation and a warning light located in the cab. The warning light is often inscrutably labeled "Shunt Trip" The label may not be visible until the warning light comes on. Once that warning light illuminates you have only a brief time prior to the operation of the shunt trip circuit. The required delay was one minute. There was still no integration with the elevator controls. If you use an elevator that was constructed under this second version of the rule the safety of everyone in the cab will depend of someone knowing which light to monitor and their stopping of the elevator immediately at the next floor of travel so that everyone can leave the cab. In all but the fastest elevators you may not have time to return to the floor from which you entered the cab.
Later versions of the rule required that these circuits be integrated with the elevator controls and automatically return the elevator to it's primary or alternate floor before shutting down all power to the elevator equipment. Although that avoids trapping firefighters in the elevator cab it can leave the initial attack team isolated several stories above the street with no backup, RIT, or any help whatsoever. In the event a firefighter or civilian has to be evacuated it will not be possible to use the elevator to do so.
Your SOP should require that the machine rooms and the shafts be checked prior to firefighters use of the elevators. That will be especially challenging in the case or top traction elevators were the machine rooms are located in a penthouse on the roof. In any operation that will be out of reach of your departments aerial apparatus were the elevators were constructed under the later versions of the shunt trip rule you should wait until your back up line and RIT is in position prior to committing your crew to the Immediately Dangerous to Life or Health (IDLH) environment.
The take away message is that you must have someone watching the conditions in the machine room and the shaft before depending on continued functioning of the elevators for firefighter safety. The wild land firefighter's mantra of Lookouts, Communications, Escape routes, Safety zones or LCES applies here.
L) You must post lookouts in the machine room and some place were they can monitor conditions in the shaft.
C) They must have an effective means of Communications with the crews in the elevator cabs.
E) Crews using the elevators should be trained on any Escape pathway out of the cabs and have the means to use it. That might include having an attic ladder or escape ropes in the cab and the means to open the doors to a floor landing that they can reach using them.
S) The Safety zone is a place that the attack crews can retreat to if the use of the elevators is lost and they cannot mitigate the emergency with the resources already at the entry points to the IDLH operational area.
I tried to alert firefighters to this hazard when this rules first came out but I could not get any interest going on the issue locally or elsewhere.