Wireless fire alarm systems are still a fairly new technology and therefore not fully understood. So, the design process includes the education of staff and building officials that are not familiar with these systems. The systems are designed to meet the same stringent UL requirements and NFPA requirements that wired fire alarm systems are required to meet. NFPA 72 references wireless fire alarm systems as “Low-Power Radio Fire Alarm Systems”. Wireless fire alarm systems are required to comply with the same NFPA 72 requirements as wired fire alarm systems, except as modified by Chapter 23.16 “Special Requirements for Low-Power (Wireless) Systems”.
Understanding How Wireless Fire Alarm Systems Work
There are two types of common wireless fire alarm systems which include point to point and a mesh networked system. A point to point system consists of the FACP, wired notification appliances, repeaters, and wireless initiating devices. Point to point systems utilize bi-directional radio frequency (RF) communication. Each initiating device reports back to a repeater and each repeater connects to either another repeater or a control unit.
A mesh networked system would consist of the FACP, wired notification appliances, gateway(s), and wireless initiating devices. The FACP communicates with the gateway, the gateway then communicates with the devices. Each device acts as a repeater in extending the signal and ensuring multiple sources of connection back to the gateway. If a device were to fail, the mesh network “heals” itself. The devices previously connected to the failed device will find the nearest working device to connect to, providing multiple pathways of connection.
A common concern within hospitals is whether the fire alarm system will interfere with any of the equipment in a hospital including ventilators and wireless internet. The frequency utilized by wireless fire alarm is within the ISM band (which includes medical devices), however, the systems utilizes several features to mitigate the impact of interference including frequency hopping and the ability to give priority to other signals. The systems are programmed to report a trouble signal for any system integrity issues.
With any project utilizing a wireless fire alarm system, whether it is a hospital or non-hospital facility, an RF site survey should be completed during the beginning stages of design to confirm wireless is a viable option. The site survey provides information on any potential interferences or poor signal areas.
Wireless fire alarm systems have been seen as a great option for historical buildings and temporary construction systems, since the devices are easy to install and remove. The wireless initiating devices remove the need for opening existing ceilings and walls to install conduit and wire. Wireless fire alarm systems can also be a great option when the facility needs to limit disruptions for other reasons, such as not being able to shut down for invasive and a lengthy construction period.
Utilizing a wireless fire alarm system allowed us to keep the existing fire alarm system active, while the install of the new fire alarm system was occurring. Additionally, the new fire alarm system was able to be fully operation with all acceptance testing completed prior to transitioning from the existing system. This made sure no relocation of the patients or staff was necessary during the installation. Additionally, this ensured minimal work was required in ceilings contaminated with asbestos.
Utilizing a wireless fire alarm system is a smart solution to many problems faced with aging buildings and temporary installations. Wireless technology is improving rapidly and affecting all aspects of construction. Wireless fire alarm systems make it easier to improve the safety of buildings while minimizing disruptions.
Check out the full guide, The Internet of Things and the Effect on Healthcare Facility Infrastructure