How to Monitor Fire Alarms on Military Bases (AC and DC power options)

By Andrew Erickson

May 9, 2024

Effective fire alarm monitoring is crucial for maintaining safety in various facilities, especially in large and complex installations such as military bases.

Recently, John Ermatinger, an engineer at Digitize, had a detailed email discussion with a Fire Protection Engineer working for a large engineering company. The project was for a military base in the US.

Email conversation between Digitize and our client

This email exchange regarding fire alarm monitoring at a military base in the western US is a great example of how to navigate varying input power voltages and communication technologies.

This conversation highlights the importance of selecting the right monitoring equipment and understanding the intricacies of integrating power supplies and communication protocols in fire alarm systems. That's especially true at important high-security facilities like army, national guard, or naval bases.

Monitoring Challenge: No 24 VDC power available. Can we use 120 VAC?

This Fire Protection Engineer sought advice on monitoring sprinkler waterflows in areas without Fire Alarm Control Panels (FACPs). His query revolved around providing 120 VAC power to Digitize Muxpad II panels and ensuring compatibility with existing infrastructure:

"We just chatted on the phone about the ability to provide 120 VAC to a Digitize MUXPAD II panel and if the panel could be provided with an internal power converter that is UL-rated."

John Ermatinger explained that, while it is possible to modify a Muxpad II for 120 VAC power, it would require a custom build. Standard Muxpad II modules are typically powered by 24VDC from FACPs, which are not always available in every building:

"The standard Muxpad II Data Gathering Module (DGM) with RS-485 copper pair communication is normally powered by the Fire Alarm Control Panel (FACP) 24VDC."

This scenario is a common challenge in installations where new monitoring points need to be added without the infrastructure to support traditional power sources.

Possible Solution: Muxpad II RF

Ideally, a fire alarm monitoring solution should be adaptable to various power sources and communication protocols, ensuring seamless integration regardless of the existing infrastructure. The system should offer flexibility in power supply options and support multiple communication methods.

Muxpad II device

The Muxpad II, available both with our without battery backup, was a possible solution for fire alarm monitoring at this military base.

John proposed an alternative to the standard Muxpad II configuration by suggesting the Muxpad II RF unit, which is powered by 110VAC with a battery backup. This approach eliminates the dependency on FACPs for power:

"The Muxpad II RF unit is a larger enclosure and is powered by 110VAC with battery backup."

Other 110 VAC Options with Higher Alarm Capacity

Digitize offers many different solutions tailored to varying installation needs. John highlighted the DGM-32/64 as a potentially better fit for the project at the military base.

DGM 32M device

The DGM-32/64 models are good for monitoring up to 32 (or 64) alarm inputs and can run on 110/120 VAC power.

The DGM-32/64 can monitor up to 64 inputs and operates on 110/120 VAC power with battery backup, providing a comprehensive monitoring solution:

"Another option we did not speak about is a DGM-32/64. This may be a better fit. This project will be using both Muxpad II and DGM-32/64 units."

The DGM-32/64 is designed to handle a large number of inputs, making it ideal for larger campuses with larger monitoring requirements. Its ability to switch between different communication methods, including RS-485, Ethernet, and fiber optics, ensures compatibility with multiple different scenarios.

Tech Specs & Applications of the DGM-32/64 Data Gathering Module

The DGM-32/64 Data Gathering Module (DGM) offers a robust solution for monitoring up to 64 End of Line (EOL) inputs. This unit is particularly suitable for installations requiring extensive monitoring capabilities, such as large military bases or other expansive facilities. Digitize Engineer John highlighted the benefits of this system:

"The DGM-32/64 is an EOL zone input unit and can monitor up to 64 inputs. The DGM-32/64 is powered by 110VAC with battery backup."

The DGM-32/64's design ensures reliable performance, even in challenging environments. It includes features such as internal lightning and surge protection, ground fault detection, and supervised inputs to report any breaks in the circuit as a trouble condition by zone. This makes it a durable choice for critical monitoring needs.

Flexible Communication Options

A significant advantage of the DGM-32/64 is its ability to adapt to various communication methods, enhancing its versatility and integration capabilities. John explained it this way:

"RS-485 copper communication is available for all the DGMs. DGMs may be purchased pre-configured for any available communication type. Converting the communication from RS-485 copper to fiber, Ethernet, radio, or other is done by installing or changing a communication card in the DGM."

This flexibility allows the DGM-32/64 to integrate seamlessly into different network environments, whether through traditional copper, modern Ethernet, or advanced fiber optic connections. Such adaptability ensures that the system can evolve with technological advancements and changing site requirements.

Practical Applications and Real-World Use Cases

The DGM-32/64 has been successfully deployed in various scenarios where robust and adaptable fire alarm monitoring is essential.

For example, it is ideal for military bases where extensive monitoring across multiple buildings and facilities is required. The system's ability to handle numerous inputs and communicate over long distances makes it suitable for large-scale installations.

Additionally, the DGM-32/64 is beneficial in settings where traditional power sources are unavailable. Its capability to operate on 110VAC with battery backup ensures continuous monitoring even during power outages. This provides an extra layer of security and reliability.

Ensuring Compliance and Safety Standards

Digitize's products, including the DGM-32/64 and Muxpad II RF, are designed to meet stringent safety and compliance standards. This ensures that installations using these systems adhere to industry regulations and guidelines, providing peace of mind to engineers and facility managers. The DGM-32/64 complies with NFPA 72 and is ETL-listed, so it adheres to high safety and quality standards, including automatic reporting of power loss:

"The DGM-32/64 is normally powered by 117 VAC through the internal step-down transformer (12VDC backup). Loss of AC power for more than 15 seconds will be reported to the System 3505 Prism LX for display. The reporting delay can be changed by the user to any value between 1-90 seconds."

This compliance ensures that the system not only meets regulatory requirements but also provides reliable and timely alerts, crucial for maintaining safety in critical environments.

Converting RS-485 Copper to Fiber/Ethernet/Radio

During this email conversation, John also emphasized the importance of considering the implications of changing equipment mid-project, noting that modifications in large contracts can lead to increased costs and delays.

However, he reassured the engineer that upgrading the communication method from copper to fiber optics is straightforward and involves only a change in the communication card:

"Converting the communication from RS-485 copper to fiber, Ethernet, radio, or other is done by installing or changing a communication card in the DGM."

This flexibility allows for seamless upgrades and future-proofing of the monitoring system without big disruptions.

Conclusion: Ensuring Reliable and Adaptable Monitoring Solutions

Digitize's Muxpad II RF and DGM-32/64 units are two examples of the robustness required for complex fire alarm monitoring installations. By offering flexible power options and versatile communication methods, these solutions cater to diverse site requirements, ensuring comprehensive and reliable monitoring.

Still, no catalog is every truly complete. Off-the-shelf gear can be unworkable when you encounter unique site conditions that require more versatile power and communication solutions. That's why we've invested so much into our in-house Engineering department at Digitize. We can adjust our designs when you encounter a trick situation, and you won't be waiting forever for the new design.

If you're working on a project that requires advanced fire alarm monitoring solutions, you should look at Digitize's range of monitoring devices. Our expert engineers are ready to assist you in selecting and implementing the right equipment to meet your specific needs.

Call Digitize at 973-663-1011 or email

Andrew Erickson

Andrew Erickson

Andrew Erickson is an Application Engineer at DPS Telecom, a manufacturer of semi-custom remote alarm monitoring systems based in Fresno, California. Andrew brings more than 17 years of experience building site monitoring solutions, developing intuitive user interfaces and documentation, and...Read More