1. A sensor assembly to be mounted in a ceiling and electrically connected to an associated light fixture, the sensor assembly comprising:a body including a sensor end and a blade end opposite the sensor end;
a sensor disposed on the body nearer the sensor end than the blade end;
a cutting blade extending from the blade end of the body in a direction opposite the sensor end, the cutting blade configured to cut an opening in the ceiling; and
at least one retainer protrusion disposed on the body between the sensor and the cutting blade, the at least one retainer protrusion configured to retain the sensor assembly in the opening of the ceiling,
wherein the at least one retainer protrusion includes a resilient retainer protrusion,
wherein the resilient retainer protrusion includes a leaf spring.