Fire alarm systems and building features wardens need to know

Wardens do not design, install or test fire alarm systems, but they need to understand what the system is telling them and what the building will do automatically when an alarm starts. A warden who knows that the stair pressurization fans have just started, that the elevators have gone to the ground floor, and that the voice message on their floor is an alert rather than an evacuation, can lead people far better than one who knows only that "the bell is ringing". This lesson covers alarm signals, single-stage and two-stage systems, voice communication, the fire alarm panel, elevators, doors, sprinklers and smoke control, from the warden's point of view.

How an alarm starts

An alarm can be started manually or automatically. Manual pull stations, located near exits, let anyone who discovers a fire raise the alarm. Automatic devices include smoke detectors, heat detectors and sprinkler water-flow switches, which signal the panel when water starts flowing in the sprinkler pipes. In many buildings, the alarm is also transmitted automatically to a monitoring company or directly to the fire department. Wardens should know whether their building's alarm is monitored, because if it is not, someone must call the fire department every time.

Even where the alarm is monitored, the plan should require a call to the emergency number from a safe place by someone who can describe what is happening, especially if they have seen fire or smoke. Monitoring companies typically pass on a signal that an alarm is active; they cannot say whether there are flames on the fifth floor or people trapped.

What the alarm sounds like

In Canada, building and fire alarm standards use the temporal-three pattern for evacuation signals in many systems: three short pulses, a pause, and repeat. Older buildings may have continuous bells or slow whoops. Visual signals, strobe lights, supplement audible signals where needed for people who are deaf or hard of hearing. CAN/ULC-S524 sets the audibility requirements for new installations.

For public mode signals, the general rule used in Canadian and US practice is that the alarm should be at least 15 dB above the average ambient sound level, or 5 dB above the maximum sound level lasting a minute or more, whichever is greater. Wardens should report any room where the alarm is hard to hear, such as a noisy plant room, a sound-insulated meeting room or a server room with loud cooling.

Single-stage and two-stage systems

In a single-stage system, any alarm-initiating device causes an evacuation signal throughout the building at once. Most small and medium buildings use single-stage systems. Everyone hears the same signal and everyone leaves.

Many larger Canadian buildings, especially high buildings, hospitals and some institutional buildings, use two-stage systems. In the first stage, an alert signal sounds throughout the building or in parts of it, warning supervisory staff and occupants that an alarm has started. Supervisory staff investigate or prepare. If the alert is not acknowledged and cancelled by trained staff within a set time, usually five minutes, or if a second device or a manual station keyed to the second stage operates, the system goes to the second stage and sounds the evacuation signal. In high buildings, the alarm signal sounds on the fire floor and nearby floors while an alert sounds elsewhere, and voice messages tell occupants what to do. Wardens must know which kind of system their building has and what each signal means.

Voice communication systems

High-rise and large buildings usually have a voice communication system that lets the chief warden, building staff or the fire service broadcast live or recorded messages to selected floors. Messages should be short, specific and repeated: what is happening, what occupants on this floor should do, which stair to use, and what not to do. Wardens should listen for voice messages and repeat them on their floor. Where the building allows wardens to call the command point, usually from a firefighter phone or warden phone near the stair, wardens should know how to use it.

The fire alarm panel

The fire alarm control panel, or annunciator at the entrance, shows where the alarm started, often by zone or by device, and shows trouble and supervisory conditions. Chief wardens and building staff should be trained to read it, because the alarm zone tells the fire service where to go and tells wardens which floor is most at risk. Floor wardens do not normally go to the panel. Wardens must never silence or reset the panel unless the plan specifically authorizes them; silencing or resetting can stop the alarm on floors that have not yet evacuated and can destroy information the fire service needs.

Elevators

When the fire alarm operates, most elevators are recalled automatically to a designated floor, usually the main entrance level, or to an alternate floor if the fire is on that level. This is called Phase I recall. Doors open and the elevators park for firefighter use. Firefighters can then operate them under Phase II firefighter service. Occupants should not use elevators in a fire unless they are designated evacuation elevators and the plan says so. Some newer tall buildings have occupant evacuation elevators designed for use in fires, and some plans use elevators under fire service control to evacuate people who cannot use stairs. Wardens must follow their building's plan, which will say clearly whether any elevator may be used and by whom.

Doors, hold-opens and stairs

When the alarm operates, magnetic hold-open devices release fire doors so that they close. Some electrically locked doors on exit routes unlock automatically. Stair doors may unlock on the stair side so that people in a stair can re-enter a floor if the stair fills with smoke; in many high buildings, stair doors must allow re-entry at set floors or all floors. Wardens should know which stair doors allow re-entry and whether access-controlled doors release on alarm.

Sprinklers and smoke control

In a sprinklered building, a fire is usually controlled or extinguished by one or a few sprinkler heads near the fire. Only the heads heated by the fire open; movies in which every sprinkler in a building goes off at once are wrong. Sprinklers greatly improve survival, but they do not make evacuation unnecessary: smoke can still spread, and occupants near the fire must leave. Many high buildings also have smoke control systems, such as stair pressurization fans that keep smoke out of stairs, exhaust fans that remove smoke from the fire floor, and dampers that close ducts. Wardens may hear fans start and feel air pressure on stair doors, which can make doors harder to open; that is normal.

Trouble, false alarms and nuisance alarms

A building that has frequent false alarms trains its occupants to ignore them. Wardens can help reduce nuisance alarms by reporting causes such as cooking in the wrong place, dust from work without detector protection, steam from showers or kettles near detectors, and aerosol sprays. They should also report trouble signals, such as a trouble light on a panel or a beeping device, which mean the system may not work properly. Every alarm must still be treated as real until the person in charge or the fire service declares otherwise.

Fire codes in Canada require that a building's fire alarm system be maintained in operating condition, that it be inspected and tested under CAN/ULC-S536, and that, when the system is out of service, the owner notify the fire department and take measures such as a fire watch until it is restored.

Questions to ask about your building's systems

A new warden can learn a great deal by walking the building with the facilities manager or the chief warden and asking a few simple questions. Is the alarm monitored, and by whom? Is it single-stage, two-stage or selective? Where are the pull stations, the annunciator and the warden phones on my floor? Which areas have strobes, and are there any rooms where the alarm is hard to hear? Which doors release or unlock on alarm, and which stair doors allow re-entry? Is the building sprinklered throughout? Does it have smoke control, and what will I hear or feel when it starts? Are any elevators designated for evacuation? The answers belong in the warden's floor notes and should be checked again after any renovation or system upgrade.