Electricity
meter, energy meter or electric meter, is a device which is used for measuring
the amount of electrical energy which is being supplied to or even produced by a
residence, machine or business. Electric meters, of which the most common type
are kilowatt hour meters, are used in electrical retailing, and the utilities
are used to record the values measured by these electric meters, to help produce
an invoice for the electricity used. Electric meters also record other
information, such as the time when the electricity was used. The most common
unit of measurement is the kilowatt hour, and the demand is measured in watts
and averaged over a period of time, most usually a quarter of an hour.