Gamewell XP95A Ionization Smoke Detector Model XP95-IThe XP95 P photoelectric sensor constantly monitors its sensing chamber and its internal electronics. The results are then reported along with the units address through the integral communications electronics located in the sensor head. The XP95 photoelectric sensor uses a patented smoke chamber and infrared smoke sensing design. The infrared emitter generates a burst of light every second, or in response to direct interrogation.