Alarm Bell Fire Sprinkler

A 6”, 120 Volt fire alarm bell. Buy it here.

Is an outside alarm required near the FDC that supplements a fire sprinkler system?

Some of the questions we receive at QRFS relate to alarm bells and their proximity to fire department connections (FDCs) in a commercial sprinkler system; usually, where an outside alarm should be mounted, and whether or not one is even required near the FDC.

As with many things in fire safety code, the short answer is “probably, but it depends on the jurisdiction governing the building and the set-up of the life safety system.” There are some guidelines provided by the National Fire Protection Association (NFPA) and some rules stipulated by the International Building Code (IBC) and International Fire Code (IFC) – which are in turn adopted in different editions by local and state governments.

Read on for the detailed answer. If you need to buy any fire sprinkler system parts, review our selection of fire alarm bells and accessories, fire department connections, and FDC accessories.

The purpose of an outside waterflow alarm in a fire sprinkler system

This external alarm, sometimes called an “outside ringer,” is connected to a waterflow indicator and is intended to notify people outside of the building that the sprinkler system has activated. In the old days, it also importantly served to signal passersby to call emergency services, though system monitoring has largely made this obsolete. What it does do, however, is let firefighters know the sprinkler is active; it can supplement alarms telling people to get or stay out of the building; and if it’s located near the FDC, it can help direct emergency responders to the location.

NFPA requires sprinkler systems of a certain size to have a waterflow alarm which, as the name makes pretty clear, sounds an alarm when the sprinkler is activated and water is flowing:

From the 2016 Edition of NFPA 13 Local Waterflow Alarms. A local waterflow alarm shall be provided on every sprinkler system having more than 20 sprinklers.

6.8.1 General.

Waterflow alarm devices shall be listed for the service and so constructed and installed that any flow of water from a sprinkler system equal to or greater than that from a single automatic sprinkler of the smallest K-factor installed on the system will result in an audible alarm on the premises within 5 minutes after such flow begins and until such flow stops.* An alarm unit shall include a listed mechanical alarm, horn, or siren or a listed electric gong, bell, speaker, horn, or siren. The alarm can be mechanically or electrically actuated. In wet and dry systems, the alarm is actuated merely by flowing water. In preaction or deluge systems, different alarms can be set off independently by the flow of water and another detection system. The waterflow alarm in any commercial system does not have to be monitored according to NFPA, though section 903.4 of the International Fire Code requires it, with some exceptions that include systems with less than 20 sprinklers.

Waterflow Detector Fire Sprinkler

A 3” paddle-style waterflow detector. “In a wet system, the moving water pushes the paddle, causing an electric contact to close, indicating water flow.” You can purchase one here.

Does a commercial fire sprinkler require an outside alarm? And does it need to be near the FDC?

Again, the answer is “probably, but it depends.” According to NFPA, an outside alarm is not always required in a more comprehensive fire safety system:

From the 2016 Edition of NFPA 13

A. Audible alarms are normally located on the outside of the building. Listed electric gongs, bells, horns, or sirens inside the building, or a combination of such used inside and outside, are sometimes advisable.

Outside alarms might not be necessary where the sprinkler system is used as part of a central station, auxiliary, remote station, or proprietary signaling fire alarm system, utilizing listed audible inside alarm devices.

NFPA is not the be-all-end-all of fire safety code, however. The ultimate power lies in the authority having jurisdiction (AHJ). These local and state governments adopt and adapt code from the IBC and IFC, which are informed by NFPA. Most state codes adopt some form of the IBC code for new construction, for example:

From the 2017 Florida Building Code - Building, Sixth Edition


An approved audible device, located on the exterior of the building in an approved location, shall be connected to each automatic sprinkler system. Such sprinkler waterflow alarm devices shall be activated by water flow equivalent to the flow of a single sprinkler of the smallest orifice size installed in the system. Where a fire alarm system is installed, actuation of the automatic sprinkler system shall actuate the building fire alarm system.

Michigan and Virginia, for other examples, employ similar code. Check with your local AHJ to discern whether an external alarm is absolutely necessary, or whether NFPA’s exception may apply for sprinkler systems “used as part of a central station, auxiliary, remote station, or proprietary signaling fire alarm system, utilizing listed audible inside alarm devices.” Also, check with the AHJ for what constitutes an “approved location” for the alarm.

That said, there are very practical reasons why this external alarm is near the fire department connection:

  1. FDCs must be visible, accessible, and unobstructed. This means it’s also a good location for an alarm intended to alert people outside the building.
  2. The alarm can help guide firefighters to the FDC.
  3. Practically-speaking, by design, both the FDC and the waterflow alarm need to be located near the fire sprinkler system riser.


Where should you mount the external waterflow alarm?

We sometimes get questions along the lines of, “How high should the alarm be above the FDC?” There really is no specific guidance from NFPA, other than the guidance on how to mount an FDC:

From the 2016 Edition of NFPA 13

8.17.2* Fire Department Connections.

A.8.17.2 The fire department connection should be located not less than 18 in. (500 mm) and not more than 4 ft (1.2 m) above the level of the adjacent grade or access level.

A. Fire department connections should be located and arranged so that hose lines can be readily and conveniently attached without interference from nearby objects, including buildings, fences, posts, or other fire department connections. Where a hydrant is not available, other water supply sources such as a natural body of water, a tank, or a reservoir should be utilized. The water authority should be consulted when a nonpotable water supply is proposed as a suction source for the fire department.* Fire department connections shall be located at the nearest point of fire department apparatus accessibility or at a location approved by the authority having jurisdiction.

A. Obstructions to fire department connections include but are not limited to buildings, fences, posts, shrubbery, other fire department connections, gas meters, and electrical equipment.

To boil this down: make sure FDCs are mounted within the correct height parameters and that they are readily accessible and unobstructed. As long as the alarm bell doesn’t get in the way, it can be placed anywhere near the FDC, and should be placed high enough to carry sound more effectively.

As for the exact location of the FDC, the NFPA 13 Handbook clarifies: “Fire department connections need to be accessible and located where the fire department can use them. Paragraph no longer requires the connection to be on the street side of buildings but in a location approved by the local fire department. The language has also been revised to coordinate with NFPA 24.”

Otherwise, NFPA 72: National Fire Alarm and Signaling Code provides mounting guidance for all notification appliances, including external alarm bells:

From the 2016 Edition of NFPA 72

18.3.5 Mounting. Appliances shall be supported independently of their attachments to the circuit conductors. Appliances shall be mounted in accordance with the manufacturer’s published instructions.

18.3.6* Connections. Terminals, leads, or addressable communication, that provide for monitoring the integrity of the notification appliance connections shall be provided.

These alarms should also be marked, as per NFPA 25:

A.8.17.1 … Approved identification signs, as shown in Figure A.8.17.1, should be provided for outside alarm devices. The sign should be located near the device in a conspicuous position and should be worded as follows:

Sprinkler Alarm Sign

Make sure the external fire sprinkler alarm is listed and protected from the elements

As with most components of a life safety system, alarms must be listed for their intended setting and use:

From the 2016 Edition of NFPA 13* Outdoor water motor-operated or electrically operated bells shall be weatherproofed and guarded.

A. All alarm apparatus should be so located and installed that all parts are accessible for inspection, removal, and repair, and such apparatus should be substantially supported.

The water motor gong bell mechanism should be protected from weather-related elements such as rain, snow, or ice. To the extent practicable, it should also be protected from other influencing factors such as birds or other small animals that might attempt to nest in such a device. Outdoor electric alarm devices shall be listed for outdoor use.

NFPA 72 provides additional detail: Appliances intended for use in special environments, such as outdoors versus indoors, high or low temperatures, high humidity, dusty conditions, and hazardous locations, or where subject to tampering, shall be listed for the intended application. Appliances subject to mechanical damage shall be suitably protected. If guards, covers, or lenses are employed, they shall be listed for use with the appliance. The effect of guards, covers, or lenses on the appliance’s field performance shall be in accordance with the listing requirements.

Check with your AHJ for specific detail on where and how to mount your sprinkler’s external waterflow alarm bell

As with so many things in fire safety, local governments rule the roost when it comes to the exact requirements, and authorities having jurisdiction have the ability to evaluate and approve different applications that don’t meet a one-size-fits-all template.

A good rule of thumb, however: Even if you happen to be in a location where an external alarm isn’t required, it’s good to have one, and it’s also a good idea for it to be located near an FDC, if one is present. This location ups the odds of the alarm being both heard and seen, and the noise can guide firefighters to the FDC’s location, as well as alert passersby.

Do you need bells, guards, or FDC components? QRFS has you covered. Check out our inventory of fire alarm bells and accessories, fire department connections, and FDC accessories. If you don’t see what you’re looking for, try the search bar at the top of the page, or just contact us and we can likely help you get the part.

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