Don't install the 120V outside horn strobe

120 Volt horn strobes do not typically have battery backup as required by NFPA 72 (Current Version)

Many times the fire sprinkler company will provide the Electrical Contractor with a 120 volt horn/strobe to mount on the outside of the riser room as part of their equipment package.

120 Volt horn strobes will not sync with the 24 volt system that is installed that does have battery backup so you cannot install both next to each other.

Bells that only activate with the flow of water (mechanical) will not normally activate when a pull station or smoke is activated. Birds often build their nests inside the outside bells which makes them useless because the bells do not function properly. 120V bells can be installed next to a 24 volt horn/strobe because they don’t have strobes so you don’t have to worry about the sync issue.

My advice as a fire alarm professional is to get the weather proof 24 volt horn strobe from your fire alarm contractor and install that instead of the one that is 120 volt that often comes with the fire sprinkler package.

Typically the 120 volt horn strobes were installed on fire sprinkler systems that did not tie to a fire alarm system although now all fire sprinkler systems are required to be monitored with a fire alarm system. This has very few exceptions such as one and two family dwellings. It used to be that there were a certain amount of sprinkler heads that you had to have in order to have the requirement to be monitored although now it does not matter how many sprinkler heads there are, all fire sprinkler systems are required to be monitored.

When we install a fire alarm system to monitor the fire sprinkler flow and tamper switches it is a basic package and often it is the shell system that can be added to after additional construction is complete.

Call Larry Love (801) 898 6003 for more information or an appointment. Larry accepts questions and corrections when you submit them with a code reference Larry.Love@jci.com

Tampers that are wired to the fire alarm give you a supervisory signal letting you know the water has been turned off.

Flow switches when monitored send an alarm which dispatches the fire department because it indicates that water is flowing.

When a flow switch is activated the outside bell or horn strobe is also activated

When any alarm such as a pull station, smoke detector or pull station (manual alarm box) is activated it sends an alarm which dispatches the fire department and activates all the horn strobes connected to the system.

If a 120 volt horn strobe is connected to the system and the power is out nothing will happen, if a 24 volt horn strobe is activated it has at least 24 hour battery backup and it will sound and flash.

There are very few exceptions to the code on when buildings with fire sprinklers do not need to be monitored. One of those exceptions is one and two family dwellings. Check locals codes as well as your insurance company requirements because often your insurance will require that your security/fire system be tied into monitor the flow switch. If the local fire marshal is ok with the 120 volt horn/strobe that is not backed up with batteries that is fine so most of the time I would not install the 120 volt bell.