NFPA 72, National Fire Alarm and Signaling Code, is not a design guide. However, the list of chapters in the table below shows how the code is configured to help. Be familiar with all the chapters and follow the minimum requirements to ensure a code-compliant system. Follow the outline of steps below.
There is no reference to occupancies in NFPA 72, so review the adopted building code (or Life Safety Code) to determine the minimum type of fire alarm system. Then, apply the requirements and guidance in NFPA 72. Most buildings have an automatic sprinkler system, so that is a given in these examples.
As always, start by reviewing the owner’s fire protection goals. In most warehouse layouts, a manual fire alarm system will be installed. Begin by laying out manual fire alarm stations at all building exits.
Do not fall into the trap of then laying out a notification appliance above the manual stations. Review Chapter 18 for the needed audible/visual appliances. Don’t automatically use combination units, because you are dealing with two different sensory devices.
Lay out the audible appliances based on achieving 15 dbA throughout every area. Consider the ambient noise levels as outlined in Chapter 18 and its associated Annex A material. Then lay out the visual appliances based on Chapter 18 requirements. Where there are audible and visual appliances close to each other, make those combination appliances.
If there are offices attached to the warehouse, you may want to install smoke detectors, placing them in accordance with Chapter 17’s requirements. If the owner wants smoke detection in the warehouse, use linear beam smoke detectors rather than spot-type, because the ceiling may exceed the normal height of 12 feet.
It is important to design the beam smoke detectors to ensure easy testing and maintenance. Before laying them out, the owner must define the storage shelving’s layout. Then interconnect all waterflow and sprinkler supervisory switches with the fire alarm system. That should suffice for detection and occupant notification in most warehouses. Connecting to a remote supervising station is a requirement of the Life Safety Code and all building codes. There are specific requirements for the travel distance between manual pull stations, but essentially the warehouse design is finished.
The next design is for a three-story, 48-unit apartment building. It is important to know if there will be any special accommodations for residents who are deaf or hard of hearing. Let’s use the example of three apartment units for individuals who are hard of hearing.
For the standard units, there must be a smoke alarm in each bedroom and in the area immediately outside the bedrooms, with all devices interconnected. For the units designated for the hard of hearing, we need to add a 15-candela (cd) strobe in each bathroom and a 117-cd strobe in every bedroom. Use smoke alarms with built-in strobes where smoke alarms are required (same as the standard units). Since the building is protected by an automatic sprinkler system, there is no need for heat detection.
NFPA 72 requires a manual fire alarm station at each exit on every floor, so review travel distances to ensure it is compliant. The building code requires system smoke detection in the hallways. If there is an atrium, use beam smoke detection, never spot-type devices. If a smoke detector is required in the boiler room, ensure the environment is acceptable for normal smoke detectors. Again, interconnect all waterflow and sprinkler supervisory switches with the fire alarm system and connect it to a remote supervising station.
In high-rises or a unique building design, hire a fire protection engineer to design the system. The goal is to stay out of trouble and to obtain AHJ approval on the first acceptance test. Show customers that you know the codes and are the professional that they should hire.