Fire Alarm general guidelines

Each project is different depending on occupancy, what is stored in the building, if the building is sprinkled or not, how high the building is and other factors so these guidelines are general and not meant to be the same for all buildings.

  1. If the building is fully sprinkled you will normally only need a smoke detector at the fire alarm each NAC power supply. If the building is not sprinkled and has to have a full coverage fire alarm smoke detectors will be required and pull stations at all exits and horn/strobes in egress pathways and in public areas as well as strobes in the restrooms.

  2. If the building is sprinkled the fire alarm contractor will provide MM monitor modules to monitor each flow switch, each tamper switch, the PIV if there is one (Post Indicator Valve), pressure switches, antifreeze, low air etc…. The Alarm Contractor needs to know exactly what needs to be monitored because these items are provided and installed by the Sprinkler company and and the fire alarm company will provide the monitor module to monitor them.

  3. If there is an elevator you will need a smoke in the elevator control room, a smoke on each elevator floor lobby, a smoke at the top of the shaft if the elevator shaft is sprinkled with a heat detector with a lower temperature than the sprinkler head. You will also need 4 CM relays for elevator recall.

  4. If you have RTU Roof Top HVAC units over 2000cfm you will need duct detectors in those units and most of the time the HVAC provides those duct detectors and the alarm contractor will need to provide MM Monitor modules to monitor if the smokes go into alarm and the EC will wire the detectors to shut down the RTU unit. Often if a belt or a motor is burning out this will protect the unit from further damage and will also stop the smoke from being moved throughout the building.

  5. If the Fire Marshal (AHJ) Authority Having Jurisdiction wants the RTUs to have global shut down then you will need CM/Relays as well as monitor modules at each duct detector. That is not very common.

  6. On very large RTUs you may have to have duct detectors on the supply and the return. The AHJ may also require that the Duct Detectors have a RTS Remote Test Switch if the detectors are very high or not easy to access.

  7. If you have dampers that need to be shut the alarm contractor will need to provide CM /Relay modules to do that.

  8. On a fully sprinkled building only one pull station is required at an AHJ approved location.

  9. Remember what I stated at the beginning of the article so if this is a clinic, school, daycare there may be different requirements. Currently Utah school require CO detectors in certain areas with a blue strobe in the office but in other buildings CO detectors are not required yet.

  10. Some systems require specific gas detectors in the parking garage but often those systems are just tied to fans and not to the fire alarm system. It depends on each application.

  11. Most buildings that require notification have to have horn/strobes 15 feet from the end of the hall and every 100 feet in halls or every 50 feet if ADA code is being followed. In rooms the spacing will vary depending on placement and how large the rooms are and where the horn/strobes are placed and the cd candela settings on the strobes as well as the volume db settings.

  12. If a 75 cd horn/strobe has a 176mA current draw then a 110 cd horn/strobe that has a larger coverage area will have a higher current draw so you cannot put as many on a circuit. Strobe only units draw less so it is important to have a professional do the battery calculations and circuit calculations to make sure the system will work as designed and have enough battery backup to power the system for 24 hours after AC power loss.

  13. Understand that some buildings are required to have Voice Evacuation or Mass Notification so instead of horn/strobe they would have Speaker Strobes which have different placement requirements so that the voice messages can be understood. Improper placement of speaker strobes can cause the appliances to cancel each other out so having an engineer design these types of systems is very important.

  14. Now that you have an alarm system with smoke detectors, heats, elevator recall, horn/strobes, damper shut down, duct detectors being monitored and RTUs being shut down, the back up batteries you need an NFPA 72 report and inspection at least once a year to meet Utah law requirements. Some insurance companies require additional inspections.

  15. Each one of these areas can be complicated and this is a short outline and not everything has been addressed. There are other areas such as smoke control where you could move smoke throughout the building using specific controls from an isolated room that the fire department can access. There are other items that can be added to the fire alarm if required like a relay if you had restaurant hoods that need to be monitored or specific preaction systems or halon or other sytsems that need to be monitored.

  16. I did a job last year where the warehouse was a cold storage unit and we ended up with about 50 monitor modules but at first they only told us about 25 of them. We also had to provide a lift that had special fluid that would work in very low temperatures. We were going to do the work before the units got turned on but they were behind schedule in some areas and ahead of schedule in other areas so we had to work in very low temperatures. This specialized work needs to have a very clear scope of work of what is required of the different contractors.

  17. This article is only meant as an outline not as a how to article. You should hire a professional Electrical Engineer to design your fire alarm system with Professional Mechanical Engineers that will do the HVAC systems as well as other systems such as elevator so all systems will work as they should.