In elevator shaft protection, where should a heat detector be located relative to the sprinkler head?

• A. Within 12 inches of the sprinkler head.
• B. Within 18 inches of the sprinkler head.
• C. Within 24 inches of the sprinkler head.
• D. Within 36 inches of the sprinkler head.

Answer: (C)

In elevator shaft protection, you want the heat detector close enough to the sprinkler head to sense the same heat plume quickly and trigger alarms in lockstep with sprinkler actuation. Placing the detector within about 24 inches of the sprinkler head achieves fast detection of a developing fire near the head, so the detection system can respond promptly and help coordinate with the suppression system. If the detector is placed farther away, the heat plume can move and dilute as it rises through the shaft, potentially delaying detection and reducing the reliability of the early warning. Positioning it within 24 inches strikes the right balance: it’s close enough for rapid sensing while avoiding direct interference from sprinkler spray and shaft dynamics, ensuring timely and coordinated protection.