Which statement about smoke detector installation in environmental air spaces is correct?

Which statement about smoke detector installation in environmental air spaces is correct?

• A. Smoke detectors may be installed beneath raised floors or above suspended ceilings (or both), including raised floors and suspended ceilings used for environmental air, to substitute for detection within the room.
• B. Smoke detectors may only be installed in the room itself.
• C. Detectors may not be used in environmental air spaces.
• D. Detectors must be mounted on exterior walls.

Answer: (B)

The main idea is that smoke detection is meant to protect the space people occupy. Placing detectors in environmental air spaces, like under raised floors or above suspended ceilings, doesn’t reliably warn occupants in time because those plenum areas move and dilute smoke differently from the room itself. To provide timely and meaningful protection for the occupied area, detectors are installed in the room rather than in the environmental air spaces. Detectors in environmental spaces are not a substitute for in-room detection and would not meet typical protection requirements.

The main idea is that smoke detection is meant to protect the space people occupy. Placing detectors in environmental air spaces, like under raised floors or above suspended ceilings, doesn’t reliably warn occupants in time because those plenum areas move and dilute smoke differently from the room itself. To provide timely and meaningful protection for the occupied area, detectors are installed in the room rather than in the environmental air spaces. Detectors in environmental spaces are not a substitute for in-room detection and would not meet typical protection requirements.