TL;DR: A local fire alarm only sounds inside your building and depends on someone present to call for help. A UL listed central station monitors your system 24/7 and notifies emergency services automatically. For most commercial properties in Denver and across the Front Range, central station monitoring is required by code and by your insurer.
When a fire alarm goes off at 2 a.m. in an empty office building, one question matters above everything else: who is going to call for help?
That question is the core difference between local fire alarm monitoring and central station monitoring. For Denver metro and Front Range commercial property owners, facility managers, and contractors, getting this distinction right is not just a safety decision — it is a code compliance decision.
What Is a Local Fire Alarm?
A local fire alarm is the most basic configuration. When a detector or pull station activates, the system sounds horns and strobes inside the building. That is the extent of its reach.
Local alarms alert occupants on-site only. Unlike local fire alarms, which only sound within the building and rely on occupants to call for help, no signal is automatically transmitted to any outside party.
Unmonitored, local-only fire alarm systems do not satisfy code in most commercial occupancies and leave notification entirely up to whoever happens to be on site.
For a warehouse, a multi-tenant office, a school, or any building that may be unoccupied overnight, that is a serious gap. A fire that starts at midnight will burn unchecked until a passerby notices smoke or a sprinkler waterflow alert reaches someone who acts.
What Is Central Station Fire Alarm Monitoring?
Central station monitoring connects your fire alarm system to an independent, staffed facility that watches for alarm, supervisory, and trouble signals around the clock.
Central station service is the most common method of fire alarm monitoring for commercial properties. A central station is an independent, third-party monitoring facility that provides fire alarm monitoring as a service to building owners.
Here is how the signal flow works:
- Detection: Sensors such as smoke detectors, heat detectors, or sprinkler waterflow sensors send an alarm to the fire alarm control panel (FACP).
- Transmission: The FACP transmits the alarm signal via cellular, IP, phone line, or radio to the central monitoring station.
- Operator response: A live operator at a central monitoring station receives the alert, immediately assesses the situation, filters out false alarms, and contacts the appropriate authorities if there is a real emergency.
- Emergency notification: Even if no one is present in the building to hear the alarm, emergency responders will still be notified right away.
To learn more about the full signal chain from sensor to dispatch, see How Commercial Fire Alarm Monitoring Works: From Sensor to Emergency Response.
The Three Types of Supervising Stations Under NFPA 72
The Supervising Stations chapter of NFPA 72 provides for three types of supervising stations: Remote Supervising Station, Proprietary Supervising Station, and Central Station Service.
Understanding all three helps clarify where central station monitoring fits and why it is the standard choice for most commercial buildings.
1. Central Station Service
Central station service is delivered by an independent, third-party company that has no ownership stake in the monitored property. This is the monitoring arrangement most commercial businesses use. Central supervising stations must meet the UL 827 Standard for Central Station Alarm Services, which requires more stringent standards than remote station monitoring.
2. Proprietary Supervising Station
Proprietary supervising stations are owned and staffed by the same organization that owns the protected buildings, typically campuses or multi-site chains. Think large university systems, hospital networks, or major retail chains with dedicated in-house security operations. This model requires significant infrastructure investment and is not practical for most businesses.
3. Remote Supervising Station
A remote supervising station is a specialized system designed to constantly monitor fire alarms from a variety of different locations. Unlike central station service, remote stations are not responsible for additional services such as installation, inspection, testing, or maintenance — they are focused solely on monitoring and recording signals sent from the fire alarm system.
All three supervising station categories require trained personnel, redundant power, and continuous signal supervision under NFPA 72.
Why UL Listed Central Station Monitoring Is the Standard
Not every monitoring company is equal. The UL listing is the benchmark that separates verified providers from everyone else.
Monitoring stations must adhere to the requirements of UL 827, the Standard for Central-Station Alarm Services, and demonstrate compliance before becoming UL Listed. UL conducts annual audits of each UL Listed monitoring company to help confirm ongoing compliance.
UL Listed stations can issue Protected Property Alarm System Certificates to customers. These certificates are a declaration of the features of the installed system and related services and are often required by insurance companies and code officials.
Working with a UL Listed central station also helps meet insurance requirements. Many insurance companies now require businesses in specific industries like healthcare, manufacturing, retail, hospitality, and education to use UL Listed central stations for fire and security system monitoring.
For a detailed breakdown of what the UL listing covers operationally, read What UL Listed Fire Alarm Monitoring Means for Your Denver Business.
What Colorado and Denver Metro Code Actually Requires
This is where the question stops being abstract for Front Range property owners.
Across Colorado fire jurisdictions, all commercial fire alarm systems are required to be monitored by an approved fire alarm monitoring company, and these systems are required to be maintained in an operating condition and tested annually by a state-licensed fire alarm system contractor.
Colorado operates under a decentralized model. The Colorado Division of Fire Prevention and Control (DFPC) sets minimum fire safety standards for specific facilities, such as public schools and state-licensed healthcare facilities. For most buildings, local governments — referred to as Authorities Having Jurisdiction (AHJs) — determine fire code requirements. This means each city, county, or fire protection district can adopt its own version of the International Fire Code (IFC) with local amendments.
The International Fire Code and Uniform Fire Code require fire alarm systems in specific applications to be monitored by an approved supervising station in accordance with NFPA 72, and fire code authorities often require these systems to be monitored by UL Listed central stations, which is consistent with requirements written in NFPA 72, Section 26.3.3.
Local amendments matter across the Denver metro. Colorado AHJs often amend the IFC to address local needs. Denver has adopted the 2024 IFC with updates for lithium-ion battery storage and carbon monoxide detection. Aurora requires remote annunciator panels in multi-family residential buildings to aid responder response. Front Range Fire Rescue mandates monitoring for all alternative extinguishing systems, such as kitchen hood suppression systems.
The practical takeaway: if your commercial property is in Denver, Aurora, Lakewood, Thornton, Westminster, Centennial, Broomfield, Parker, or any other Front Range jurisdiction, do not assume a local-only alarm satisfies your AHJ. It almost certainly does not.
Central Station vs. Local Alarm: Side-by-Side Comparison
| Feature | Local Alarm Only | UL Listed Central Station |
|---|---|---|
| Notifies occupants on-site | Yes | Yes |
| Automatically contacts emergency services | No | Yes |
| 24/7 staffed operator coverage | No | Yes |
| Satisfies commercial code in most CO jurisdictions | No | Yes |
| Acceptable to most commercial insurers | No | Yes |
| Trouble and supervisory signal monitoring | No | Yes |
| Documented record-keeping for AHJ review | No | Yes |
Who Needs What: Practical Guidance by Building Type
While your AHJ has final authority, here are general patterns that apply across Denver metro and Front Range commercial properties.
Central Station Monitoring Is Standard For:
- Multi-tenant office buildings — occupied by rotating staff and tenants who cannot be responsible for monitoring after hours
- Warehouses and industrial facilities — large footprints, limited overnight staff, high property values at risk
- Healthcare facilities and schools — the Colorado DFPC sets minimum fire safety standards specifically for public schools and state-licensed healthcare facilities, and central station monitoring is the baseline expectation
- Restaurants and retail spaces — high occupancy and kitchen suppression systems that require monitored signals
- Data centers — pre-action and suppression systems require both alarm and supervisory signal monitoring
- High-rise and mixed-use buildings — Denver has seen significant growth in high-rise and mixed-use construction; these building types come with more complex fire alarm requirements around voice evacuation, zoned notification, and firefighter communication systems
When Proprietary Monitoring May Apply:
- Large institutional campuses (universities, hospital networks) with dedicated in-house security operations and the infrastructure budget to support a staffed proprietary station
When a Local-Only Alarm Is Never Enough:
- Most commercial properties, schools, and healthcare facilities are legally required to have 24/7 monitoring. If your building falls into any of these categories, a local-only alarm is not a compliant option.
Consequences of Getting It Wrong
Compliance involves more than just having the hardware — it requires a contract with a UL Listed central station and regular inspections to ensure communication paths remain functional. Failing to meet these standards can lead to heavy fines or the denial of insurance claims after a fire.
For fire alarm systems required to be monitored by Colorado code, notice must be made to the fire code official whenever alarm monitoring services are terminated, and that notice must be made in writing by the provider of the monitoring service being terminated. The AHJ tracks your monitoring status — gaps in coverage do not go unnoticed.
How Pre Action Fire, Inc. Handles Monitoring for Denver Metro Businesses
Pre Action Fire, Inc. provides fire alarm monitoring through a UL listed central station, meeting the requirements of NFPA 72 and the International Fire Code as adopted across Denver, Aurora, Lakewood, Arvada, Westminster, Thornton, Littleton, Englewood, Broomfield, Centennial, Parker, and every other jurisdiction we serve on the Front Range.
Our NICET certified technicians handle the full picture: system installation, monitoring setup and contract documentation, annual NFPA 25 and NFPA 72 compliance inspections, and 24/7 emergency service when something goes wrong. Same-day service is available for urgent needs.
If you are unsure whether your current monitoring arrangement satisfies your AHJ, or if you are planning a new build or tenant improvement in the Denver metro area, contact Pre Action Fire, Inc. at preactionfire.com or call our Denver office to schedule an assessment.
Recommended Reads
- How Commercial Fire Alarm Monitoring Works: From Sensor to Emergency Response
- What UL Listed Fire Alarm Monitoring Means for Your Denver Business