Abstract: A programmable switch includes a housing. A sensor is associated with the housing. The sensor senses a measurable physical property of a sensed element proximate the housing and developing an electrical signal varying relative thereto to represent the sensed physical property. A logic circuit is disposed in the housing and receives the electrical signal. The logic circuit includes a memory for storing a reference value and a controller for comparing the reference value to the sensed physical property to determine status of the sensed physical property. An input circuit is operatively associated with the logic circuit for selectively changing the stored reference value to reprogram the switch. An output switch is operatively associated with the logic circuit to externally indicate status of the sensed property.