In practice the consumer would get the supply company's agent in before the supply ran out and pay only for the charge consumed as read from the scale. It was therefore necessary for the consumer to pay for a further supply of electricity, whereupon, the supplier's agent would unlock the meter from its mounting and invert it restoring the mercury to the reservoir and the supply. Once the mercury pool was exhausted, the meter became an open circuit. Like all other DC meters, it recorded ampere hours.

As current was drawn from the supply, electrochemical action transferred the mercury to the bottom of the column. This consisted of a vertically mounted glass structure with a mercury reservoir at the top of the meter. The electrochemical meter was labor-intensive to read and not well received by customers.Īn early type of electrochemical meter used in the United Kingdom was the 'Reason' meter. At periodic intervals the plates were removed and weighed, and the customer billed. Thomas Edison at first worked on a direct current (DC) electromechanical meter with a direct reading register, but instead developed an electrochemical metering system, which used an electrolytic cell to totalise current consumption. Many experimental types of meter were developed. For example, if a meter recorded that 100 ampere hours had been consumed on a 200-volt supply, then 20 kilowatt-hours of energy had been supplied. Since the voltage of the supply should remain substantially constant, the reading of the meter was proportional to actual energy consumed. Īn Aron type DC electricity meter showing that the calibration was in charge consumed rather than energyĪs commercial use of electric energy spread in the 1880s, it became increasingly important that an electric energy meter, similar to the then existing gas meters, was required to properly bill customers, instead of billing for a fixed number of lamps per month.ĭC meters measured charge in ampere hours. Also, in some areas meters have relays for demand response load shedding during peak load periods. 'Time of day' metering allows electric rates to be changed during a day, to record usage during peak high-cost periods and off-peak, lower-cost, periods. When energy savings during certain periods are desired, some meters may measure demand, the maximum use of power in some interval. They are usually read once each billing period. They are typically calibrated in billing units, the most common one being the kilowatt hour ( kWh). North American domestic electronic electricity meterĪn electricity meter, electric meter, electrical meter, energy meter, or kilowatt-hour meter is a device that measures the amount of electric energy consumed by a residence, a business, or an electrically powered device.Įlectric meter or energy meter measures the total power consumed over a time interval.Įlectric utilities use electric meters installed at customers' premises for billing and monitoring purposes.

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