An electric meter or energy meter is a device that measures the amount of electrical energy consumed by a
residence, business, or an electrically-powered device. Electric meters are typically calibrated in billing units,
the most common one being the kilowatt hour. Periodic readings of electric meters establishes billing cycles
and energy used during a cycle. In settings when energy savings during certain periods are desired, meters
may measure demand, the maximum use of power in some interval. In some areas, the electric rates are
higher during certain times of day, to encourage reduction in use. Also, in some areas meters have relays to
turn off nonessential equipment.