Interfacing Elevators and Fire Alarm Systemsby Merton Bunker, P.E., Rolf Jensen & Associates, Inc.

Elevators have been used since the Roman Empire flourished more than a millennium ago, but vertical transportation has changed considerably since then.  As cities became more crowded, buildings grew taller, and elevator use greatly expanded. It is estimated that there are currently 600,000 passenger elevators in the United States, with 750,000 in North America, safely carrying 12 billion people annually without incident. Modern elevators are the safest form of transportation on the planet. But it wasn't always that way.

Many safety features have been introduced in the past 80 years or so. In fact, the first edition of ASME A17.1, Safety Code for Elevators was published in 1921. Requirements for elevators were added to the National Electrical Code® in 1920, where they appeared as Section 43a. Elevators used early in the 20th century lacked many of the safety features we presently take for granted. For example, many elevators were located in open hoistways, which acted as chimneys during a structure fire. They also lacked other fire safety features such as shunt trip and recall.

There were many cases of high-rise fires in New York City where fires would impinge on the elevator lobby call buttons, shorting them out, thereby calling elevator cars to the floor that was on fire. Any unfortunate occupants in the car would generally be trapped without any chance of escape. In fact, two incidents in the late 1960s and early 1970s resulted in multiple fatalities. But modern elevators are designed to interface with fire alarms to safely transport occupants to a safe landing in the event of a fire.  They also disconnect (shunt trip) electrical supplies if sprinklers wet down equipment in the elevator machine room or hoistway.

Commercial smoke detectors weren't available until the mid 1960s, and weren't required by code for recall purposes until 1973. The use of smoke detectors for Phase I Recall has undoubtedly resulted in saving many lives. Newer requirements, such as shunt trip and shunt trip power supervision have also made elevators safer. However, these safety features increase the complexity of the systems.

Of primary interest to fire alarm and electrical contractors are the interfaces between the fire alarm system, the elevator controller, and the shunt trip breaker. The ties between the elevator controls and the fire alarm system help ensure proper elevator recall (Phase I Emergency Operation) and shunt trip during fire emergencies. 

ASME A17.1-2001, Safety Code for Elevators and Escalators, requires Phase I Emergency Recall and shunt trip. A17.1 is adopted in every U.S. jurisdiction, except Pennsylvania.  However, Pennsylvania is in the process of adopting it at this time. ASME A17.1 in turn references NFPA 70, National Electrical Code and NFPA 72, National Fire Alarm Code for the electrical and fire alarm installations, respectively. Phase II

Firefighter's Operation is used by the fire service to shuttle firefighters and equipment, especially in tall buildings. It is only possible to use Phase II Operation by use of a special key. Phase I Recall is also important because the fire service can quickly determine that all elevators are parked in the lobby, and there are no passengers trapped in the hoistway.

Phase I Emergency Recall Operation

The primary purpose of Phase I Emergency Recall Operation is to return elevator cars to a safe location during a fire, so passengers will be able to safely escape. Requirement 2.27.3.2.3(a) of A17.1-2001, Safety Code for Elevators and Escalators requires elevator cars to return nonstop to the Designated Level (chosen by the Authority Having Jurisdiction [AHJ]) upon actuation of a fire alarm-initiating device in an elevator lobby, other than those located at the Designated Recall Level. Requirement 2.27.3.2.3(b) and (c) require the actuation of a fire alarm initiating device in a hoistway or elevator machine room to also cause the car(s) to return nonstop to the Designated Level. However, actuation of an alarm-initiating device located in the hoistway at or below the lowest level of recall must cause the car(s) to return to the upper level of recall.

Requirement 2.27.3.2.4(a) of A17.1 requires that an alarm initiating device actuation at the Designated Level must cause the car(s) to return to the Alternate Level (also chosen by the Authority Having Jurisdiction). It should be noted that unique architecture, such as split-level lobbies, might affect the decision in determining the Designated Level

Section 6.15.3 of NFPA 72-2002, National Fire Alarm Code provides requirements for fire alarm equipment used for Phase I Emergency Recall Operation. Specifically, Section 6.15.3.1 requires system powered smoke detectors located in elevator lobbies, elevator machine rooms, and hoistways to be connected to the building fire alarm system.  If there is no building fire alarm system, Section 6.15.3.2 additionally requires the installation of a fire alarm control unit specifically dedicated for the purposes of elevator control.  This panel must be identified as "elevator recall control and supervisory panel" on system drawings and on the control unit itself. The panel should be located in a lobby or other area where the alarm and trouble signals can be heard.

It is important to note that Section 6.15.3 does not require any occupant notification or other initiating devices beyond those required for elevator control. NFPA 101, Life Safety Code or local building codes will provide requirements specifying where occupant notification is required. Finally, Section 6.15.3.3 requires only the elevator lobby, machine room, and hoistway smoke detectors to cause Phase I Emergency Recall Operation, unless specifically required by the Authority Having Jurisdiction.  Some local codes require any alarm initiating device to cause Phase I Emergency Recall Operation, so be sure to check them before programming the control unit.

Section 6.15.3.5 requires smoke detectors in elevator lobbies to be within 21 feet of the centerline of each elevator door within the elevator bank under control of the detector. This requirement closely follows the requirements of Chapter 5 (NFPA 72) for detector

spacing. However, non-smooth or high ceilings will require detector spacing to be determined by the requirements of Chapter 5. Unenclosed lobbies (such as atriums) present unique challenges and will require an engineering evaluation to determine spacing. In these cases, consultation with a qualified designer is recommended.

Section 6.15.3.6 does not permit smoke detectors to be installed in unsprinklered elevator hoistways, unless used to actuate smoke relief equipment. This requirement exists because hoistways are not always the best environment for smoke detectors. Hoistways are also generally considered inaccessible, which makes maintenance difficult and expensive. However, smoke detectors (or other appropriate automatic fire detectors) are required in sprinklered hoistways because they are necessary to recall cars before sprinkler actuation causes a shunt trip, or to provide the recall feature to move cars away from a fire in the hoistway pit if the bottom of the hoistway is sprinklered. Wet brakes and electrical equipment can cause erratic elevator operation and pose a serious threat to passenger safety. A shunt trip immediately stops the car(s), whether occupants are inside them or not. Therefore, it is necessary to provide Phase I Emergency Recall Operation (allowing passengers to escape), then disconnect the power supply before waterflow.  NFPA 13, Standard for the Installation of Sprinkler Systems provides the requirements for locations of hoistway sprinklers, and shunt trip is discussed later in this article.

Non-air conditioned elevator lobbies, such as in an open parking structure or unheated lobby, pose significant challenges for designers. These lobbies are essentially outdoors and are considered as damp locations. ASME A17.1 requires Phase I Emergency Recall Operation, but smoke detectors are not suited to outdoor environments.  Section 6.15.3.7  permits other types of automatic detection where the environment is not suited to smoke detection. Generally, heat detection is considered an acceptable and affordable alternative to smoke detection in these areas, but any listed automatic detection is permitted under this exception.

Section 6.15.3.8 requires the actuation of elevator Phase I Emergency Recall Operation alarm initiating devices to cause an alarm signal on the building fire alarm system and requires the indication of the actuated device on any required annunciators.  Section 6.15.3.9 also requires the actuation of elevator machine room and hoistway smoke detectors to cause separate and distinct visible annunciation and to alert firefighters that the elevators are no longer safe for them to use. One way this is accomplished is by flashing the fire hat in the car to alert the firefighter to exit the car.  Elevator machine room and hoistway smoke detectors are not required to initiate a building-wide alarm if the signal is indicated in a constantly attended location. The term "constantly attended" is intended to mean coverage on a 24/7 basis. Additionally, an exception to Section 6.15.3.9 permits the elevator machine room and hoistway smoke detectors to cause a supervisory signal, with permission of the Authority Having Jurisdiction.  The exception is commonly applied where on-site personnel, such as a guard, constantly monitor the fire alarm system controls.

In order to communicate the Phase I Emergency Recall Operation signals to the elevator controls, Section 6.15.3.10 requires at least three control circuits to connect the fire alarm

system controls to each group of elevator controllers.  The first circuit is for the Designated Level lobby alarm initiating devices.  The actuation of the Designated Level smoke detector must cause actuation of this circuit, and would send the elevator car(s) to the Alternate Level. If the elevator has both front and rear doors, smoke detectors in each lobby must actuate the recall feature. It should be noted that Section 6.15.2.2 requires the relay for the control device to be placed within 3 feet of the circuit or device being controlled in order to minimize the amount of non-monitored wiring.

The second circuit is to provide recall features for initiating devices located in the remaining lobbies, the elevator machine room and hoistway.  Actuation of these devices will send the car(s) to the Designated Level.  The third circuit is for actuation of the alarm initiating devices in the elevator machine room and hoistway. This circuit will be used by the elevator controller to flash the firefighter's hat symbol in the car, and is intended to indicate that the elevator(s) are no longer safe to use on Phase II Operation.  Where the elevator machine room is located on the Designated Level, the elevator machine room smoke detector must also cause actuation of the first circuit.

Some designers and installers have used auxiliary contacts on smoke detectors to act as the elevator control circuits. This practice violates Section 4.4.7.1 of the Code because the conductors between the detectors and elevator controls are not monitored for integrity. Listed relays or control modules should be used in lieu of this practice.

Elevator Shutdown (Shunt Trip)

Elevator shutdown, frequently referred to as shunt trip, is intended to immediately stop elevators before water from elevator machine room or hoistway sprinklers affects brakes and electrical equipment.  Both wet brakes and wet electrical equipment can cause erratic life threatening elevator operation. Therefore, it is required by Requirement 2.8.2.3.2 of A17.1 to cause disconnection of the main line power supply upon or prior to the application of water from sprinklers in the machine room or hoistway. This occurs even if the elevator car is occupied and not at a landing. Pit sprinklers located less than 2 feet above the pit floor are exempt from this requirement because Requirement 2.8.2.3.4 of ASME A17.1 requires all electrical equipment within 4 ft of the pit floor to be NEMA 4 rated. Therefore, heat detectors or waterflow switches will typically not be required for shunt trip involving pit sprinklers. 

There are several methods of causing shunt trip. One method involves heat detectors near sprinklers with the understanding that they will operate before the sprinkler fuses. A second method is to employ the use of a waterflow switch with no time delay. Additionally, there are systems that utilize heat detectors, controls, and solenoid valves to recall the car(s) before causing shunt trip. These systems offer greater occupant safety, but may cost more than other methods.

Section 6.15.4.1 requires heat detectors used for shunt trip to have a lower temperature rating and a higher sensitivity than the sprinklers in the area.  A lower temperature rating will help ensure that the heat detector actuation (and shunt trip) occur before water

flows.  Additionally, Section 6.15.4.2 requires a heat detector within 2 feet of each sprinkler. Control modules or relays can then be used to operate the shunt trip circuit.

Waterflow switches can be used to cause shunt trip, however, there must be no time delay between the flow of water and the disconnection of the main line power supply, as it will violate A17.1.  This precludes the use of devices with built-in delay, commonly called retard, because it can be adjusted to provide a delay in signal transmission to the control unit.  There are zero retard devices available, however, they may respond to surges in pressure, causing unwanted shunt trip operation.

It is the practice of many designers to use heat detector contacts in the shunt trip circuit without connecting them to the fire alarm system. This arrangement avoids the use of a control unit, separate relay, or control module. However, this practice violates Section 6.15.4.2 because all fire alarm system wiring must be monitored for integrity. Heat detectors, waterflow switches, or pressure switches must be connected to and monitored by the fire alarm system for this reason.

Control circuits that cause main line power disconnection must be monitored for the presence of operating voltage.  There have been cases where the shunt trip breaker operating power was disconnected, which could have permitted the elevator car to operate after sprinkler waterflow.  Section 6.15.4.4 is intended to prevent such an occurrence. 

Car Notification Appliances

Notification appliances are no longer required in elevator cars by NFPA 72. Section 3-8.4.1.3.5.6.3 of NFPA 72-1999 required a loudspeaker in each elevator car, where an emergency voice/alarm communications system was installed. This was required because elevators typically traversed many floors (zones).  However, this requirement was deleted for the 2002 Code because occupants will hear the signal when they arrive at a zone in alarm.

If speakers are installed in cars, it is recommended that audible appliances of low power output or low tap setting be used because of the confined area involved.  A circuit on one of the elevator traveling cables will be required for this purpose. Be sure to discuss this with the elevator contractor early in the design process if the feature is necessary.

Summary

Elevator safety has advanced considerably in the past 80 years.  Improvements in electrical safety devices, fire alarms, and sprinklers undoubtedly have resulted in countless saved lives.  As our ability to integrate systems continues to advance, we will continue to improve elevator safety beyond its lofty achievements of the past.

Interfacing systems is not tremendously difficult. The real challenge is to ensure good coordination between fire alarm, sprinkler, and elevator designers and contractors. Good communication and an understanding of code requirements will help ensure safe systems.

Merton Bunker is a senior consulting engineer with Rolf Jensen & Associates at their Fairfax, VA office.