Exhausting Smoke Detection

Code Requires Smoke Alarms

Only a small portion of Chapter 24 of NFPA 101 pertains to smoke detection — Section 24.3.4, titled, “Detection, Alarm, and Communications Systems.”

Although electrical contractors, electrical engineers and architects are usually the people who work with smoke alarm and smoke detector placement in new homes, alarm dealers should know what code requires in this regard as it may affect their work at some point in time.

According to Section 24.3.4.1, smoke alarms are required in all sleeping rooms, outside each sleeping area, and on each level of the home. Most smoke alarms installed in new homes are powered by 120VAC with 9V battery backup. The battery assures operation during power outages. Section 24.3.4.3, however, allows for the use of smoke alarms that operate exclusively from batteries.

The plain fact is, everywhere you go there are smoke alarms and that’s because local jurisdictions have adopted NFPA 101, or they incorporate it in their own state or local ordinances.

The real meat behind NFPA 101, and smoke alarm and smoke detector installation lies in Section 9.6.2.9, titled, “Smoke Alarms.”

Interconnection and Notification

Section 9.6.2.9.3 calls for interoperability where when one smoke alarm goes off, they all go off. This type of system is commonly called a tandem line system, where each smoke alarm connects to the other through a traveler (a common wire used for general signaling).

When one smoke alarm goes into alarm, it triggers the others by changing the electrical state of the tandem conductor. The same traveler can trigger ancillary relays in order to actuate lights and other peripherals. These relays should be specifically listed for the specific smoke alarm units in use.

The systems approach employs metallic cable that runs from detector to detector throughout the home. Alarm signals are sent to a centralized alarm panel where they are processed, analyzed and acted on in a number of ways. This includes local annunciation as well as remote signaling at a supervising station or central monitoring station.

Another method of interconnection between alarm control and smoke detector is provided via radio waves. For the specifics behind wireless smoke detection and its use, refer to NFPA 72.

Occupancy Classifications

Occupant notification is important and NFPA 101 covers a good bit of ground in Chapter 9. “The alarms shall sound only within an individual dwelling unit, suite of rooms, or similar area and shall not actuate the building fire alarm system, unless otherwise preferred by the authority having jurisdiction. Remote annunciation shall be permitted” (Section 9.6.2.9.4, NFPA 101, 2006).

Every facility built has an occupancy designation as defined by NFPA 101 and the International Code Council (ICC).

“The occupancy of a building or structure, or portion of a building or structure, shall be classified in accordance with 6.1.2 through 6.1.13. Occupancy classification shall be subject to the ruling of the authority having jurisdiction where there is a question of proper classification in any individual case.” (Section 6.1.1.1, Occupancy Classification, NFPA 101, 2006 Edition.)

Churches, for example, are commonly
classified under Assembly (Section 6.1.2). School buildings are most often classified under Institution, and there are others, such as Industry, Storage, Business, and more.

Another source of structural classifications comes from ICC, based in Washington, D.C. ICC provides a comprehensive list of classifications within the context of International Fire Code (IFC).

All of this is important because every job you do will bear one or more occupancy classifications and an occupancy load. It’s this designation(s) that acts to determine what you, as the fire alarm dealer, must do to adequately protect a specific building, complex or compound.

Al Colombo is an award-winning writer who has covered electronic security and life safety since 1986. Visit his Web site at www.firenetonline.com.

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