Fire alarm bells are essential components of any fire alarm system, ensuring that occupants are alerted promptly in the event of an emergency. Proper installation is critical not only for functionality but also for compliance with fire safety codes and standards. This guide provides a detailed overview of the installation process for fire alarm bells, including mounting, wiring, and testing procedures. It is based on information from official manufacturer instructions and technical guides from trusted sources in the fire safety industry.
Introduction
Fire alarm bells are available in various sizes, voltages, and configurations, including 6-inch, 8-inch, and 10-inch models rated for either 120-volt or 24-volt systems. These devices are typically mounted in indoor or outdoor locations and are often housed in protective back boxes to ensure durability and safety. The installation process involves several key steps: selecting the appropriate mounting height, removing the gong or bell casing, wiring the device to the power source, mounting the bell in a back box, and testing the system for functionality and audibility.
All installation procedures must be carried out by qualified electricians, as improper installation can lead to equipment damage or personal injury. Additionally, fire alarm systems must comply with the National Fire Protection Association (NFPA) standards, particularly NFPA 72, which outlines the requirements for fire alarm system components, including notification appliances.
Mounting and Placement
Choosing the Correct Mounting Height
The first step in the installation process is selecting an appropriate mounting height. According to installation guides and NFPA 72, fire alarm bells should be mounted at least 8 feet (2.4 meters) from the floor and as close to the ceiling as possible. This height ensures that the sound is projected effectively and is audible throughout the intended area. The exact mounting height may also depend on the manufacturer’s specifications, as outlined in their published instructions.
Mounting the bell at a higher position also helps prevent accidental damage from people or objects. In outdoor installations, additional considerations such as weather resistance and vandalism protection are necessary.
Mounting the Bell in a Back Box
Once the height is determined, the next step is to mount the bell in a standard square outlet box or, preferably, a fire alarm bell back box. Unlike standard outlet boxes, back boxes provide added protection for the bell’s wiring from dirt, dust, moisture, and other environmental hazards. This is especially important for outdoor installations, where exposure to wind and rain can lead to short circuits and wiring failures.
To install the bell in a back box, align the bell’s housing unit with the back box using the included bolts. Secure the bolts in the designated holes to ensure a stable fit. The back box is typically equipped with a gasket that forms an air- and water-tight seal, further protecting the internal components from damage.
Disassembly and Wiring
Removing the Gong
Before wiring the bell, it is necessary to remove the gong, which is the red bowl-like structure surrounding the inner components. Most models feature a hex bolt or Phillips screw located near the center of the gong. Loosening this fastener allows the gong to be gently removed for access to the wiring.
This step is important for both installation and maintenance, as it provides access to the internal wiring and ensures that the gong can be reattached after the device is fully connected.
Wiring the Alarm Bell
Wiring a fire alarm bell requires careful attention to the type of current used by the device. Fire alarm bells operate on either alternating current (AC) or direct current (DC), and the wiring schemes for these two types differ. AC bells, typically rated at 120 volts, have a four-wire configuration, while DC bells require different connections depending on the system’s power supply.
Prior to beginning the wiring process, the power supply to the bell must be turned off. This is typically done by switching off the circuit breaker and securing it with a lock-out/tag-out device to prevent accidental re-energization. Once the power is off, the wires from the bell can be connected to the corresponding wires in the wall.
A helpful reference for wiring is a four-wire guide, which can serve as a starting point for both AC and DC models. It is important to ensure that the wires do not touch each other and that the connections are secure but not over-tightened. Each wire should be connected to the appropriate terminal on the device, and the order of connection is generally not critical.
Reassembly and Final Steps
Reattaching the Gong
After the wiring is complete, the gong can be reattached. There are typically two holes on the gong itself that align with positioning pins on the bell’s housing unit. These holes must be properly aligned to ensure a secure fit. Once in place, the bolt that was previously removed can be re-tightened to secure the gong in position.
This is also an appropriate time to install any additional protective components, such as a wire guard or bell guard. These accessories help prevent damage from nesting birds, vandalism, and light impacts. Bell guards are available in 12-inch sizes and are designed to fit 6-inch, 8-inch, and 10-inch alarm bells.
Testing the Bell
The final step in the installation process is testing the bell to ensure that it is functioning correctly. The bell must be audible in all areas designated by the authority having jurisdiction (AHJ). This may include different rooms or zones within a building, depending on the fire alarm system’s configuration.
Testing also involves verifying that the wiring is correct and that the bell is producing a sufficient sound level. In some cases, the National Fire Protection Association (NFPA) requires that the audibility of the bell be adjusted based on the average ambient noise level in the area. This ensures that the alarm can be heard even in noisy environments.
Additional Considerations
Compliance with Fire Safety Standards
Fire alarm systems must adhere to NFPA 72 standards, which define the requirements for the installation, testing, and maintenance of fire alarm components. These standards specify that notification appliances, including fire alarm bells, must be mounted in accordance with the manufacturer’s instructions and must meet specific audibility criteria.
For example, NFPA 72 requires that notification appliances be mounted at a height prescribed by the manufacturer and that the sound level be sufficient to alert all occupants within the designated area. These requirements ensure that the fire alarm system functions effectively in the event of an emergency.
Weather Resistance and Durability
Fire alarm bells installed in outdoor locations must be protected from the elements. This is typically achieved through the use of weather-resistant back boxes and bell guards. These components are designed to prevent water and dirt from entering the bell’s housing and to protect the internal wiring from corrosion and damage.
Weather-proof back boxes are made from durable materials that resist wear and tear, while bell guards are typically constructed from corrosion-resistant materials to ensure long-term durability. These protective measures are especially important in outdoor installations where exposure to wind, rain, and sunlight is common.
Conclusion
Proper installation of a fire alarm bell is a critical step in ensuring the effectiveness of a fire alarm system. From selecting the correct mounting height to wiring the device and testing its functionality, each step must be carried out with precision and care. By following the manufacturer’s instructions and adhering to fire safety standards such as NFPA 72, installers can ensure that the bell operates correctly in the event of an emergency.
Fire alarm bells are available in various sizes and voltages, and additional accessories such as back boxes and bell guards can provide added protection and durability. It is important to note that only qualified electricians should perform the installation, as improper handling can lead to equipment failure or personal injury.