When deciding between a hard-wired Fire Detection and Alarm System (FDAS) and a wireless FDAS, some things have to be considered.
Generally, new buildings, where the wires can be hidden inside finished walls and ceilings, are a prime candidate for a completely hard-wired system. On the other hand, older buildings, especially historical buildings, and temporary structures are better off using wireless communications because there’re no wires to hide or keep changing.
Wireless Fire Alarm is a Hybrid System
Most wireless fire alarm systems, though, are a hybrid systems of wireless and hard-wired. Inputs like detectors, pull stations, and input modules can be wireless. However, even when they’re controlled by wireless control modules, all horns, strobes, and speakers have to be hard-wired; there are wires from the power supply to the device. That’s because these devices take power to run, and the radio waves used in the wireless system just don’t carry that kind of power.
That means that there will probably be some hard-wired aspects to any fire alarm system, even if it’s called a wireless system.
All fire alarm systems require two stand-alone power sources. As its primary source, the fire alarm control panel has utility power, and as backup power to the primary source, it uses batteries. In a fire alarm system, any wireless device does not have utility power. As its primary source, it uses a battery and as its backup power source, it uses a second battery.
Because the batteries are the sole source of power In the wireless devices, most manufacturers require the batteries to be replaced every couple of years. If there are 10 smoke detectors, that’s 20 batteries. If there are 100 smoke detectors and modules, that’s 200 batteries.
Besides the cost of the batteries every couple of years, the time needed to replace the batteries is a regular maintenance cost to operating the fire alarm system. In small systems, replacing batteries in a wireless fire alarm system isn’t much of a cost. However, as the system gets bigger, like fire alarm systems with hundreds to thousands of wireless devices, the regular maintenance cost to replace the batteries is something that needs to be considered.
Radio waves are tricky. Getting a radio signal from a wireless device may not be much of a problem in a wooden structure, but in an all metal building, a radio signal from a wireless detector may not get anywhere. Most buildings have concrete reinforcement, metal studs, and electrical wiring. All of these affect the radio signals.
Before installing a wireless fire alarm system, a complete site evaluation is needed to show where problems are going to occur.
Between a wireless and a hard-wired fire alarm system, there are some off-setting costs. For the wireless system, the devices do cost more, but because wireless devices don’t need the installation cost
of wiring, that cost is off-set
In a new building, however, the cost of wiring is much lower than the cost of wiring would be in an existing building. This is because before the walls and ceilings are completed, the wiring can easily be installed. If the building already exists, hiding the wiring behind already finished and completed walls requires a lot of creativity and a lot extra time.
If the building is existing, wireless fire alarm systems might be the better choice, if the building is being erected, a hard-wired system may be the better choice.