System Sensor | 5603A Mechanical Heat Detector | 135°F (57°C) Fixed Temperature

The System Sensor 5603A Mechanical Heat Detector is a reliable fixed-temperature heat detector engineered for commercial, industrial, and institutional fire alarm systems. The detector activates when ambient temperatures reach 135°F (57°C) and is designed for locations where smoke detection may result in nuisance alarms or where environmental conditions make smoke detectors impractical.

Unlike rate-of-rise models, the 5603A uses a non-resettable fixed-temperature element that responds when a specific temperature threshold is reached. Once activated, the external collector drops from the detector body, providing a clear visual indication of the alarmed device.

The detector includes a versatile mounting bracket compatible with multiple electrical box configurations, simplifying installation across a wide range of building types.

Features & Benefits

• Single-circuit mechanical heat detector
• Fixed-temperature thermal sensing
• 135°F (57°C) activation temperature
• Non-resettable fixed-temperature design
• External alarm collector for visual indication
• UL maximum spacing of 25 ft x 25 ft on 10 ft ceilings
• Reversible mounting bracket for flush or surface mounting
• Compatible with common electrical backboxes
• Low-profile appearance
• Non-polarized wiring terminals
• UL, ULC and FM approved

Technical Specifications

• Model: 5603A
• Circuit Type: Single Circuit
• Sensor Type: Fixed Temperature
• Fixed Temperature Rating: 135°F (57°C)
• Maximum Installation Temperature: 100°F (38°C)
• UL Maximum Coverage: 25 ft × 25 ft
• Operating Humidity: 5% to 95% RH (non-condensing)
• Mounting Options: Single-gang, 3.5″ octagonal, 4″ octagonal, 4″ square with plaster ring
• Listings: UL, ULC, FM Approved

Typical Applications

• Storage rooms
• Utility rooms
• Mechanical spaces
• Elevator machine rooms
• Industrial environments
• Areas subject to dust, steam, or airborne contaminants