Lutron MS-OPS6M2U-DV-WH Maestro Switch with Occupancy / Vacancy SensorTo power the sensing circuit, occupancy sensing switches require a small flow of current when the load is in the OFF state. This can be accomplished by connecting the power supply return wire to ground or to neutral. Local codes in certain municipalities require that a neutral conductor be run to the switch box, regardless of construction. In one particular instance, installing occupancy sensors that use the ground wire to function is not permitted.