• Photoelectric 2-Wire Smoke Detector with CleanMe & Heat Sensor

The UTC 521BXT self-diagnostic, two-wire smoke detector is a conventional direct-wire smoke detector with analog features such as remote maintenance/trouble reporting (CleanMe), drift compensation, and multi-criteria detection.

The 521BXT continually monitors its own sensitivity and operational status, and provides a visual and remote trouble condition if the unit drifts out of the sensitivity range or fail internal diagnostics.

The 521 BXT is equipped with both a rate-of-rise and fixed temperature sensor and operates on 6.5 - 33 VDC.


  • 2-wire
  • Photoelectric
  • Heat sensor
  • CleanMe remote maintenance reporting reduces false alarms
  • Smart dual fixed/rate of rise heat works with photo chamber to catch fires faster
  • Built-in drift compensation reduces false alarms
  • Field replaceable optical chamber makes servicing a snap
  • Small, low profile design blends in with any environment

Technical Specifications:

  • Voltage: DIP switch 1 ON for standard 12V operation (6.5-20 VDC), polarity sensitive
  • Maximum ripple: (pk to pk) 10% (V p-p)
  • Typical average standby current: 70 uA (12/24V)
  • Typical alarm current (12/24V): up to 60mA max. if not limited by control panel
  • Aux. relay contacts: 2A @ 30VDC
  • Alarm contacts: 500mA @ 36VDC (resistive)
  • Photoelectic sensitivity: 3.1% + 0.5 - 1.0%
  • Operating termperature: 32 degrees to 100 degreesF (0 degrees to 37 degreesC)
  • Operating humidity range: 0 to 95% non-condensing
  • RFI immunity: 20V/m minimum; 0-1000MHz
  • Color: White head and base
  • Field wiring size: 12-24 AWG
  • Detector packaging: 10 detectors per carton
  • Heat detector specifications rate of rise: - 15 F/min and >105 F (8.3 C/min and >40.6 C)
  • UL 2-wire compatibility identifier: DIP switch 1 ON S09A, DIP switch 1 OFF S10A, S11A (RX models)
  • Drift compensation adjustment: 1.0%/ft. max
  • Detector head dimensions: 5 in. (12.7cm) diameter; 2 in. (5cm) height
  • Mounting dimensions: 4.75 in. (12.1cm) diameter; 0.3 in. (0.8cm) height
  • Reset time: 1 second minimum
  • Listings: 511 UL 268

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Photoelectric 2-Wire Smoke Detector with CleanMe & Heat Sensor

  • Product Code: UTC:521BXT

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