The HAI 20A Hardwired High Wattage Relay Control Module is part of the HAI energy management line of products. It was primarily designed for residential homes to control power being consumed by high current appliances that include a water heater, pool pump, baseboard heater, fountains, ventilator, humidifier and dehumidifier. It can also be used In small commercial applications for lighting ballasts, vent fan control, a circulator pump, sign lighting and outdoor lighting. The idea behind this module is to prevent expensive energy use by locking out the use of high wattage appliances and lights when electricity costs are at their highest. It is optoisolated to isolate noisy loads from interfering with your HAI automation system. The HAI 20A Hardwired High Wattage Relay Control Module requires a connection with an HAI Central Automation Control System or Expansion Module which will give you the ability to schedule operating times and programs for high wattage appliances through HAI's scheduling features. Additionally, the module has a built-in manual override switch.