Interlogix 521B

2-wire, photoelectric, 6-24 VDC, UL listed

  • Factory New
  • Material Obsolete
Brand: Interlogix Part #: 45094 Categories: , Manufacturer Part #: 521B


500N Series two-wire conventional photoelectric smoke detectors bring together trusted technology and a full line of features that meet the demands of both residential and commercial applications. The 500N offers sounders in two-wire applications, specifically to meet residential code requirements.

Interlogix is also proud to offer proven technology like CleanMe®, dust compensation, field replaceable optical chambers, and self-diagnostics. CleanMe® is only available on the 500N 2-wire models and will communicate with compatible FACPs when servicing is required.

500N Series detectors work on a light-scattering principle. A pulsed infrared light-emitting diode serves as the light source, and a high-speed photo diode as the sensing element. This design protects against nuisance alarms caused by dust, insects, RF interference, and ambient light.


Weight 1 lbs
Dimensions 5.50 × 5.50 × 2.00 in
Detection Method



Production Status




Product Notes

Replacement: 2W-B


  • Remote maintenance (CleanMe®) reporting and built-in drift compensation reduces false alarms
  • Self-diagnostics meets NFPA 72 sensitivity testing requirements without the need for external meters
  • Field-replaceable optical chamber makes service fast and simple
  • Large SEMS screw terminals accept 12-18 AWG wire
  • Small, low profile design blends with any environment
  • Optional auxiliary functions include:
    • Integrated sounder with optional interconnection
    • Auxiliary relay is NFPA 72 listed for applications such as elevator recall
    • Fire system isolated heat detector, integrated with non-latching single station smoke detector
    • Integrated fixed/ROR heat detector
    • Adaptor plate enables replacing legacy 400 Series with 500N Series smoke detectors


Data Sheet: Smoke Detectors with Auxiliary Functions, 500N Series
Installation Sheet: ESL 500N Series Smoke Detector
Compatibility Index: ESL Smoke Detector