A sensor assembly may be mounted in a ceiling used with an associated light fixture. The sensor assembly may include a body including a sensor end and a blade end opposite the sensor end. A sensor may be disposed on the body nearer the sensor end than the blade end. A cutting blade may be disposed on the body nearer the blade end than the sensor end. The cutting blade may be configured to cut an opening in the ceiling. At least one retainer protrusion may be disposed on the body between the sensor and the cutting blade. The at least one retainer protrusion may be configured to retain the sensor assembly in the opening of the ceiling.