An FBH/FAS system combines two critical fire safety installations: the Fire Brigade Hydrant (FBH) system, which supplies water for firefighting, and the Fire Alarm System (FAS), which detects fire and alerts building occupants. Together, they form the backbone of a building’s fire protection strategy. What you need to include depends on your building’s size, occupancy type, and local codes, but the core components fall into clearly defined categories.
Fire Alarm System: Control Panel
The control panel is the brain of your FAS. It receives signals from every detector and manual device in the building, processes that information, and decides when to trigger alarms and send notifications to monitoring services. It also monitors all connected devices for faults, displays system status through indicator lights or screens, and manages power switching.
A key requirement is backup power. Batteries must be sized to run the entire fire alarm system for 24 hours in standby mode, then 5 minutes in full alarm. If your system includes voice evacuation (recorded messages guiding occupants out of the building), that alarm-mode requirement increases to 15 minutes. Even if your building has an emergency generator, you still need batteries as a failsafe, though in that case they only need to cover 4 hours of standby instead of 24.
Detection and Initiating Devices
These are the sensors and manual triggers that actually identify a fire condition. Your system should include a combination of the following:
- Smoke detectors pick up smoke particles in the air early, often before flames appear. The standard nominal spacing is 30 feet (about 9 meters) between detectors, which is considered adequate for life safety objectives in most ceiling heights. Unlike heat detectors, there are currently no code-required spacing adjustments for smoke detectors based on ceiling height.
- Heat detectors activate when the surrounding temperature rises beyond a set threshold. These are better suited for kitchens, garages, and other areas where smoke detectors would produce frequent false alarms. Spacing requirements for heat detectors do change based on ceiling height.
- Manual pull stations let occupants trigger the alarm by hand if they spot a fire before detectors activate. These are typically placed near exits and stairwells.
Most systems benefit from a mix of detector types placed according to the specific hazards in each zone of the building.
Notification Appliances
Once a fire is detected, the system needs to alert everyone in the building quickly and clearly. Your FAS should include both audible and visual notification devices.
Audible alarms (sirens or horns) must produce a sound pressure level at least 15 decibels above the average ambient noise in the space. However, the combined sound of ambient noise plus all alarm devices operating together cannot exceed 110 dBA at the minimum hearing distance. In environments where ambient noise already exceeds 105 dBA, audible alarms aren’t required at all, and you rely entirely on visual notification.
Visual alarms, typically strobe lights, are required for occupants with hearing impairments and in high-noise environments. Voice evacuation systems add another layer, delivering recorded instructions that guide people toward exits. These are especially valuable in large or complex buildings where occupants may not know the layout well.
Fire Brigade Hydrant: Water Supply
The FBH system exists to give firefighters a reliable, pressurized water supply when they arrive on scene. Fire flow is measured at 20 psi residual pressure, and for any building beyond a one- or two-family dwelling, the minimum flow rate cannot be less than 1,000 gallons per minute. Your local authority may require significantly more depending on building size, construction type, and contents.
Hydrant Placement and Protection
Where you put hydrants matters as much as what you install. Hydrant outlets must face the fire apparatus access road. When a hydrant has multiple outlets and not all can face the road (common with hydrants on landscape islands in parking lots), the 4-inch outlet takes priority.
Hydrants cannot be placed behind parking stalls or anywhere vehicles or objects are likely to block them. They also shouldn’t be positioned where fire apparatus staged at the hydrant would block turning radii for other emergency vehicles, unless alternative routes exist.
Physical protection is required wherever hydrants are exposed to vehicle collisions. If vehicles can approach from multiple directions, four concrete-filled bollards (4 inches in diameter, mounted in concrete) should be arranged in a square around the hydrant, spaced at least 3 feet from its perimeter. If the hydrant can only be approached from one side, two bollards are sufficient.
Fire Department Connections
Fire department connections (also called Siamese connections) allow firefighters to pump supplemental water into your building’s sprinkler or standpipe system from their engine. These are a required component of the FBH infrastructure and have specific installation standards:
- Size and threading: Connections for sprinkler and standpipe systems use a 2½-inch Siamese connection with national standard hose thread.
- Height: The connection must be installed between 18 and 48 inches above grade.
- Visibility: It must face the fire lane, be clearly visible, and sit within 50 feet of the fire lane.
- Security: All connections need locking caps to prevent tampering or debris entry.
- Hose run: The hydrant used to supply the fire department connection should be close enough that the total hose line running from the hydrant through the fire engine to the connection does not exceed 100 feet.
Standpipes for Taller Buildings
If your building is four or more stories, you need standpipes. These are vertical pipes running through the building that provide water outlets on each floor, so firefighters don’t have to drag hose up stairwells from ground level. Standpipes must be installed and operational before the building reaches 40 feet in height during construction, not just at final occupancy.
Ongoing Testing and Maintenance
Installing the system is only half the job. Both dry barrel and wet barrel hydrants require annual inspections and must be inspected again after every operation. Annual flow testing verifies that each hydrant delivers adequate water pressure and volume. All stems, caps, plugs, and threads need to be lubricated annually to ensure they operate smoothly when needed.
On the FAS side, the control panel monitors connected devices continuously for faults, but manual functional testing on a scheduled basis is essential. Battery capacity, detector sensitivity, and notification appliance performance all degrade over time and need periodic verification. Your local fire code and the edition of NFPA 72 adopted in your jurisdiction will specify exact testing intervals.
Applicable Codes and Standards
The two primary standards governing these systems are NFPA 72, which covers fire alarm and signaling systems (current edition: 2025), and NFPA 25, which governs the inspection, testing, and maintenance of water-based fire protection systems including hydrants. NFPA 72 extends beyond traditional fire alarms to include mass notification systems for weather emergencies, chemical threats, and other large-scale hazards. Local building codes and fire marshal requirements layer additional rules on top of these national standards, so always confirm what your jurisdiction has adopted before finalizing your system design.