Use the Power Check energy meter with any standard 120-volt appliance or electronic device to measure voltage, electricity costs and electric consumption to determine the operating costs of various appliances, such as refigerators, room air conditioners, computers and lamps, identify your home's high-energy use appliances, predict your savings in reducing appliance use, calculate the cost savings for replacing older appliances with energy-effecient models, discover your "energy vampires" - appliances that use energy even when switched off.