What Happens When a Commercial Fire Alarm Goes Off? A Step-by-Step Guide

When a commercial fire alarm goes off, horns begin sounding, strobes start flashing, employees stop working, and customers look for direction.

What happens next can determine how safely and quickly everyone responds.

A commercial fire alarm system is designed to detect a possible fire, warn everyone inside the building, initiate programmed safety functions, and—when professionally monitored—send an emergency signal to a monitoring center.

However, the system can only do its job when building occupants respond correctly.

Employees should never wait to see flames, smell smoke, or determine whether the alarm is false. Every unexpected commercial fire alarm should be treated as a real emergency until emergency responders or other authorized personnel determine that the building is safe.

This step-by-step guide explains what happens when a commercial fire alarm goes off, how monitored and local-only fire alarms differ, what employees should do, and when a professional fire alarm technician should inspect the system.

What Happens When a Commercial Fire Alarm Goes Off?

When a commercial fire alarm activates, the following events will typically occur:

1. A fire alarm device detects a condition or someone activates a manual pull station.
2. The fire alarm control panel receives and processes the signal.
3. Horns, strobes, speakers, or other notification appliances activate.
4. Employees, customers, tenants, and visitors evacuate.
5. A monitored system transmits the signal to a monitoring center.
6. The monitoring operator follows the property’s established response procedures.
7. Emergency responders may be dispatched.
8. The building remains evacuated while the condition is investigated.
9. Authorized personnel silence and reset the fire alarm system.
10. A qualified fire alarm technician inspects or repairs the system when necessary.

The specific response can vary based on the fire alarm system, monitoring agreement, local fire department procedures, building type, and requirements of the authority having jurisdiction.

Why Commercial Fire Alarm Systems Are Important

A commercial fire alarm system is more than a collection of smoke detectors.

It is an integrated life-safety system designed to identify a potential emergency, alert building occupants, communicate important information, and support a coordinated response.

A commercial fire alarm system may include:

• Smoke detectors
• Heat detectors
• Manual pull stations
• Fire sprinkler waterflow switches
• Sprinkler valve tamper switches
• Duct smoke detectors
• Horns, speakers, bells, and strobes
• Fire alarm control panels
• Remote annunciators
• Emergency voice communication equipment
• Elevator recall equipment
• Door-release devices
• HVAC shutdown controls
• Fire alarm monitoring communicators

The National Fire Protection Association’s NFPA 72, also known as the National Fire Alarm and Signaling Code, addresses fire detection, occupant notification, emergency communications, supervising stations, inspection, testing, and maintenance.

Businesses should work with a qualified commercial fire alarm company to determine which requirements apply to their property.

B&W Fire Security provides professional commercial fire alarm and security services for properties throughout Northern Arizona.

Step 1: A Fire Alarm Device Detects a Possible Emergency

A commercial fire alarm begins when an initiating device detects an abnormal condition or someone manually activates the system.

Different initiating devices respond to different conditions.

Smoke detectors

Smoke detectors are designed to detect airborne particles that may be associated with smoke or combustion.

A smoke detector may activate because of:

• An actual fire
• Overheated electrical equipment
• Cooking smoke
• Steam
• Construction dust
• Aerosol sprays
• Excessive contamination
• Improper detector placement
• A damaged or malfunctioning device

Even when smoke is not visible, a smoke detector activation must be taken seriously.

Electrical components, wiring, machinery, appliances, and concealed building spaces can begin overheating before occupants see flames.

Heat detectors

Heat detectors respond to temperature rather than smoke.

Some heat detectors activate when the surrounding temperature reaches a predetermined level. Others detect a rapid increase in temperature.

Heat detectors may be used in areas where smoke detectors could be affected by dust, moisture, steam, or normal operating conditions.

Because a heat detector typically requires a substantial temperature condition before activating, its signal should never be ignored.

Manual pull stations

A manual pull station allows a person to activate the building’s fire alarm system after discovering smoke, flames, or another emergency.

When it is safe to do so, a person who discovers a fire should:

• Activate the nearest manual pull station.
• Begin evacuating.
• Call 911 from a safe location.
• Provide emergency dispatchers with as much information as possible.

Employees should be trained to recognize manual pull stations and understand when they should be used.

Fire sprinkler waterflow switches

When a fire sprinkler operates, water begins moving through the sprinkler piping.

A waterflow switch can detect that movement and send an alarm signal to the fire alarm control panel.

A sprinkler waterflow alarm may indicate:

• An operating fire sprinkler
• A damaged sprinkler head
• A broken sprinkler pipe
• Unauthorized work on the sprinkler system
• Significant water movement within the system

Commercial sprinkler systems and fire alarm systems often work together. Learn more about B&W Fire’s commercial fire sprinkler system services.

Sprinkler supervisory devices

Not every signal means there is an active fire.

A supervisory signal indicates an abnormal condition involving a monitored fire-protection system. One common example is a sprinkler control valve that is no longer in its normal operating position.

A valve tamper switch may send a supervisory signal if someone partially or completely closes the valve.

A closed sprinkler valve can prevent water from reaching the sprinklers during a fire. Read our guide to fire sprinkler tamper switches to learn why these devices are important.

Step 2: The Fire Alarm Control Panel Processes the Signal

The fire alarm control panel is the central operating component of the system.

When the panel receives a signal, it processes the information and initiates the programmed response.

Depending on the system, the panel or annunciator may display:

• The type of signal
• The affected building zone
• The device address
• The floor or room involved
• The time of activation
• Whether the condition is an alarm, supervisory, or trouble signal

An addressable fire alarm system may identify the specific device that activated. A conventional system may identify a broader zone containing several devices.

This information helps emergency responders and trained personnel locate the source of the alarm.

However, employees should not gather around the control panel or delay evacuation while attempting to decide whether the condition is serious.

Step 3: Horns, Strobes, and Speakers Alert the Building

Once the system enters an alarm condition, its notification appliances activate.

Depending on the building and system design, notification may include:

• Horns
• Bells
• Speakers
• Flashing strobes
• Voice evacuation messages
• Low-frequency sounders
• Specialized notification appliances

Audible notification appliances warn occupants who can hear the alarm. Visual notification appliances help alert people who are deaf or hard of hearing and people working in noisy environments.

Larger buildings may have emergency voice or alarm communication systems that provide recorded or live instructions.

OSHA explains that workplace alarms should be distinctive and recognized by employees as a signal to evacuate or perform another action identified in the workplace emergency plan. Businesses can review OSHA’s guidance on reporting emergencies and employee alarm systems.

Step 4: Employees and Visitors Evacuate

The most important response to a fire alarm is immediate evacuation.

When a commercial fire alarm sounds:

• Stop working.
• Leave through the nearest safe exit.
• Follow the posted evacuation route.
• Use stairs instead of elevators.
• Help direct customers and visitors toward an exit.
• Close doors behind you when practical.
• Go to the designated assembly area.
• Remain outside until authorized to return.

Never delay evacuation to gather personal belongings, finish a task, shut down nonessential equipment, or investigate the alarm.

Never assume it is a false alarm

Employees may become less responsive when a building has experienced repeated unwanted alarms.

That complacency can become dangerous during a real emergency.

An alarm caused by cooking smoke, dust, or equipment trouble should still be handled according to the building’s emergency procedures. The underlying cause should then be corrected so repeated alarms do not continue.

Do not use elevators

Elevators may become unsafe because of smoke, loss of power, or other fire-related conditions.

Many commercial fire alarm systems initiate elevator recall when specific devices activate. This function returns elevators to a designated landing so occupants do not unknowingly travel toward the affected floor.

Occupants should normally use approved stairs unless emergency personnel or an established accessibility plan provides different instructions.

Account for employees at the assembly area

Once outside, employees should report to the designated assembly area.

Managers or assigned employees should account for personnel without sending anyone back inside.

Missing employees, visitors, or contractors should be reported to emergency responders. Untrained employees should never reenter the building to search for someone.

The U.S. Fire Administration’s workplace fire-safety guidance encourages businesses to teach employees about exits, escape routes, fire-protection equipment, and workplace fire hazards.

Step 5: A Monitored Fire Alarm Transmits the Signal

If the commercial fire alarm is professionally monitored, the system sends the signal to a supervising or monitoring station.

The transmission may include:

• The property name
• The account number
• The property address
• The signal type
• The activating device or zone
• The time of activation
• Other programmed account information

Fire alarm signals may be transmitted through cellular communication, internet protocol, radio networks, or another approved communication pathway.

The system should also monitor the condition of its communication pathway. If the panel cannot communicate correctly, it may display or transmit a trouble signal.

Professional monitoring can be especially important when:

• The building is unoccupied.
• An alarm occurs overnight.
• The property is in a rural location.
• Employees cannot safely reach a telephone.
• No one outside the building can hear the alarm.

Learn more about 24/7 fire and security monitoring in Northern Arizona.

Step 6: The Monitoring Center Processes the Signal

After receiving the signal, the monitoring operator follows procedures established for the account.

Those procedures may depend on:

• The type of signal
• The property’s monitoring agreement
• Applicable fire codes
• Local fire department requirements
• The authority having jurisdiction
• Approved property instructions
• Whether additional signals are received

Possible actions may include:

• Contacting the appropriate emergency communications center
• Notifying designated property representatives
• Documenting the signal
• Processing additional signals
• Following special account instructions

Not every fire alarm system or signal is processed in exactly the same way.

Business owners should ask their fire alarm provider how alarm, supervisory, and trouble signals are handled.

Understanding Alarm, Supervisory, and Trouble Signals

Commercial fire alarm systems can generate several types of signals. Understanding the difference helps property owners respond appropriately.

Fire alarm signal

A fire alarm signal indicates a possible fire-related emergency.

It may come from:

• A smoke detector
• A heat detector
• A manual pull station
• A fire sprinkler waterflow switch
• Another fire-detection device

A fire alarm signal requires immediate evacuation and emergency response.

Supervisory signal

A supervisory signal indicates an abnormal condition involving another fire-protection system.

Examples include:

• A sprinkler valve in the wrong position
• Low pressure in a dry-pipe sprinkler system
• A fire pump condition
• Low water level in a fire-protection tank
• An abnormal suppression-system condition

A supervisory signal may not indicate active smoke or fire, but it could mean that an important fire-protection system is impaired.

Trouble signal

A trouble signal indicates a system fault or loss of normal operation.

Common trouble conditions include:

• Low batteries
• Loss of electrical power
• Communication failure
• Damaged wiring
• Ground faults
• Missing devices
• Disabled equipment
• Failed system components

Trouble signals should never be ignored.

An unresolved system problem may prevent a device from detecting a fire, warning occupants, or transmitting a signal.

Step 7: Emergency Responders Investigate

When emergency responders arrive, they may review the fire alarm panel, examine the affected area, and look for smoke, heat, flames, waterflow, or other hazards.

Building managers should be prepared to provide:

• Access keys
• Lockbox information
• The location of the fire alarm panel
• Building floor plans
• Emergency contact information
• Details about the alarm
• Information about hazardous materials
• Information about occupants who may need assistance

Employees and managers should remain outside at the assembly area unless emergency personnel direct them otherwise.

Step 8: The Building Remains Evacuated

The alarm becoming quiet does not necessarily mean that the building is safe.

The notification appliances may be silenced while the system remains in an alarm condition. Firefighters may also need additional time to investigate electrical equipment, concealed spaces, sprinkler activation, ductwork, or other potential hazards.

No one should reenter the building until the fire department or another authorized person declares that it is safe.

Step 9: Authorized Personnel Silence and Reset the System

Silencing and resetting a fire alarm system are not the same action.

Silencing the system

Silencing normally stops or changes the operation of audible notification appliances.

It may not:

• Clear the initiating condition
• Reset a smoke detector
• Restore a pull station
• Correct a trouble condition
• Return the system to normal operation

Resetting the system

A system reset attempts to return the fire alarm panel and connected devices to their normal condition.

The system should only be reset after:

• Everyone has evacuated.
• The emergency has been investigated.
• The cause of the activation has been identified.
• Emergency responders have completed their work.
• The initiating device has been restored.
• Authorized personnel approve the reset.

Employees should never repeatedly reset an active alarm just to stop the noise.

Resetting the panel without identifying the cause may erase valuable information, delay service, or cause occupants to ignore a continuing hazard.

Step 10: A Fire Alarm Technician Evaluates the System

A qualified fire alarm technician may need to inspect, test, repair, or document the system after an alarm.

Professional service may be needed when:

• A detector activated without an obvious cause.
• The fire alarm will not reset.
• A trouble condition remains.
• A pull station must be restored.
• A sprinkler system operated.
• Fire or water damaged system components.
• The communication equipment failed.
• The same alarm continues to occur.
• Emergency responders request service.
• Part of the system was impaired or disabled.

A technician may review the panel’s event history, inspect the affected device, test system components, verify monitoring communication, and document any repairs.

B&W Fire Security provides commercial fire alarm and sprinkler inspections throughout Northern Arizona.

What Happens With a Local-Only Fire Alarm?

A local-only fire alarm alerts occupants at the property but does not automatically transmit its signals to a monitoring station.

When a local-only fire alarm goes off:

1. The initiating device sends a signal to the panel.
2. The panel activates the building’s horns and strobes.
3. Occupants evacuate.
4. Someone must call 911 from a safe location.
5. Building representatives arrange for system service.

A local alarm can provide important warning to the people inside the building. However, it may not notify anyone when the property is empty.

This can create a gap in protection when an alarm occurs:

• Overnight
• During weekends
• During holidays
• In an isolated part of the building
• At a vacant property
• At a remote Northern Arizona location

A professionally monitored fire alarm can transmit signals around the clock, even when no one is present.

Should Employees Call 911 if the Fire Alarm Is Monitored?

Employees should follow the building’s emergency action plan.

When someone sees smoke, flames, an injury, or another active emergency, that person should call 911 from a safe location.

Do not delay calling because you assume the monitoring center has already contacted emergency responders.

A person at the scene may be able to provide information the alarm system cannot, including:

• The location of visible smoke or flames
• Whether anyone may still be inside
• Whether someone is injured
• Which entrance responders should use
• Whether hazardous materials are present
• How quickly the situation is changing

The monitoring system transmits the alarm condition. A direct call can provide additional information about what is happening at the property.

Common Causes of Unwanted Commercial Fire Alarms

Not every alarm activation is caused by a large visible fire.

Common causes include:

Cooking smoke

Smoke from commercial kitchens, employee break rooms, and cooking appliances may enter nearby detectors.

Steam and humidity

Steam from dishwashing, showers, cleaning, or manufacturing operations may affect improperly located smoke detectors.

Construction dust

Drywall work, sanding, drilling, demolition, and sweeping can contaminate detectors.

Fire alarm devices should never be covered, removed, or disabled without approved impairment procedures.

Aerosol products

Cleaning products, paint, insect-control sprays, and other aerosols may affect smoke-detection equipment.

Electrical problems

Overheated wiring, damaged appliances, overloaded circuits, and failing equipment can produce smoke before visible flames appear.

Dirty or damaged detectors

Dust, insects, contamination, age, and physical damage can cause unwanted alarms or interfere with detector performance.

Sprinkler-system activity

A damaged sprinkler head, frozen piping, leaking equipment, system maintenance, or an operating sprinkler may activate a waterflow signal.

Repeated unwanted alarms should not be dismissed as normal. They may indicate an environmental issue, poor device placement, inadequate maintenance, or a malfunctioning component.

Our guide to common fire alarm violations explains additional problems that can cause failed inspections and unreliable system operation.

What Should a Business Do After an Unwanted Alarm?

Once the building has been declared safe, the incident should be documented and investigated.

Property managers should:

1. Record the date and time.
2. Identify the device or zone that activated.
3. Document activities occurring nearby.
4. Note any smoke, steam, dust, or unusual conditions.
5. Review the fire alarm panel history.
6. Contact the fire alarm service provider when appropriate.
7. Correct the cause of the activation.
8. Review employee response procedures.
9. Update the emergency plan if problems were identified.

Repeated unwanted alarms can cause alarm fatigue. Employees who assume every alarm is false may respond too slowly during a real emergency.

How Businesses Can Prepare Before an Alarm

The middle of an emergency is not the time to create an evacuation plan.

Businesses should prepare employees, maintain their systems, and establish responsibilities before an alarm occurs.

Develop an emergency action plan

An emergency action plan should address:

• Emergency reporting procedures
• Evacuation routes
• Alternative exits
• Designated assembly areas
• Employee responsibilities
• Procedures for customers and visitors
• Assistance for occupants with disabilities
• Methods for accounting for employees
• Emergency contact information
• Communication with emergency responders
• Employees authorized to operate the panel

OSHA states that emergency action plans should be specific to the workplace and address evacuation policies, reporting mechanisms, emergency conditions, and alarm systems. Businesses can use OSHA’s Emergency Action Plan development guide to improve their planning.

Depending on which OSHA standards apply, an emergency action plan may need to be written and available for employee review. Review the requirements under OSHA Standard 1910.38.

Train employees

Employees should know:

• What the fire alarm sounds and looks like
• Which exits they should use
• Where they must assemble
• Who is responsible for calling 911
• Who accounts for employees
• Who may operate the panel
• Who contacts the fire alarm service company
• That they cannot reenter without authorization

OSHA recommends that employees know at least two possible exit routes, understand the building’s alarm signals, and report malfunctioning safety systems. Additional information is available through OSHA’s employee emergency-preparedness guidance.

Keep exits clear

Exit doors, corridors, stairways, and evacuation paths should remain accessible.

Do not block exits with:

• Storage boxes
• Furniture
• Decorations
• Deliveries
• Equipment
• Trash
• Temporary construction materials

Maintain accurate monitoring contacts

Update the monitoring account whenever:

• A manager leaves
• A telephone number changes
• Building ownership changes
• A tenant moves in or out
• Access codes change
• Emergency responsibilities are reassigned
• Lockbox or access information changes

Outdated emergency contacts can delay communication during an alarm.

Schedule regular inspections and testing

Commercial fire alarm systems require periodic inspection, testing, and maintenance.

Routine service can identify:

• Weak batteries
• Dirty detectors
• Damaged horns or strobes
• Communication problems
• Ground faults
• Loose or damaged wiring
• Disabled devices
• Improper programming
• Missing documentation
• Building changes that affect the system

Learn how often commercial fire alarms must be tested and review what to expect during an annual fire alarm inspection.

Commercial Fire Alarm Service in Northern Arizona

When a commercial fire alarm goes off, detection devices, notification appliances, monitoring equipment, emergency contacts, employee training, and professional maintenance must work together.

B&W Fire Security Systems provides complete commercial fire alarm services, including:

• Fire alarm system design
• Fire alarm installation
• Fire alarm inspections
• System testing
• Fire alarm monitoring
• Troubleshooting and repairs
• Fire sprinkler inspections
• Commercial fire-protection services

We serve Prescott, Prescott Valley, Chino Valley, Dewey-Humboldt, Camp Verde, Sedona, Flagstaff, Yavapai County, Coconino County, and surrounding Northern Arizona communities.

To schedule a commercial fire alarm inspection or request service, call 928-772-8008 or contact B&W Fire Security.

Frequently Asked Questions

What should I do first when a commercial fire alarm goes off?

Begin evacuating immediately through the nearest safe exit. Do not wait to see smoke or confirm that the alarm is real. Report to the designated assembly area and remain outside until authorized to return.

Does a commercial fire alarm automatically call the fire department?

A professionally monitored fire alarm can transmit a signal to a monitoring station. The monitoring operator then follows the property’s established response procedures. A local-only system generally does not transmit signals outside the building.

Should I call 911 when the building has a monitored fire alarm?

Call 911 from a safe location when you see smoke, flames, injuries, trapped occupants, or another active emergency. Do not assume someone else has already provided emergency dispatchers with information.

Can an employee reset a commercial fire alarm?

Only authorized and properly trained personnel should operate or reset the fire alarm panel. The system should not be reset until the emergency has been investigated and the appropriate authority approves the reset.

Why did the fire alarm go off when there was no visible fire?

Possible causes include cooking smoke, steam, construction dust, aerosol products, overheated electrical equipment, detector contamination, equipment failure, sprinkler waterflow, or manual activation.

What is the difference between an alarm, supervisory, and trouble signal?

An alarm signal indicates a possible fire-related emergency. A supervisory signal indicates an abnormal condition involving a fire-protection system. A trouble signal indicates a system fault, such as low batteries, damaged wiring, power loss, or communication failure.

What happens when a fire alarm goes off after business hours?

A monitored fire alarm can send a signal to a monitoring center even when the building is empty. A local-only alarm may sound without anyone present to hear or report it.

Can employees silence the alarm?

Most employees should not silence, disable, or reset a commercial fire alarm. Only trained and authorized personnel should operate the panel after following emergency procedures.

How often should commercial fire alarms be inspected?

Inspection and testing frequency depends on the equipment, system design, manufacturer instructions, applicable codes, and requirements of the authority having jurisdiction. A qualified fire alarm company can establish the correct schedule.

Who should repair a commercial fire alarm?

Commercial fire alarms should be serviced by qualified personnel who understand the system, manufacturer requirements, applicable codes, and required inspection and testing procedures.