Lutron Low Voltage Power Packs are what make Lutron Occupancy Sensors go round, using house or industrial current and converting it to DC Voltage. Each of the Power Packs can handle up to three devices, or they can be used to power a standalone Occupancy Sensor. The Lutron PP-SH Relay provides 20A line voltage and controls the load. It can be sold separately to accommodate the needs of any system setup. For example, it can switch additional loads when used with line voltage packs. However, the relay is automatically included in all Power Packs. Power Packs work respectively with 120-volt, 277-volt, and 230-volt systems. But they are all equipped for only indoor operation, testing well within a temperature range of 32 - 104 degrees Fahrenheit and not being overly fond of humidity. Units can be mounted with a single nut and can be placed inside or outside the junction box.