Electric demand meters are installed by utility companies supplying electricity to properties with high average electricity usage. Electricity demand is measured in kilowatts per hour.
An electric demand meter measures electricity usage over periods of 15 minutes on a dial, with the highest rate of electricity usage over a 15 minute period recorded by the meter. The highest kilowatt use over a 15 minute period during a billing period is recorded until a meter reader resets the electric demand meter.
Electricity customers with high usage are usually provided with electric demand meters in order to record the highest period of demand. For example, electricity provider National Grid U.S. provides an electric demand meter for clients who average 2,000 kilowatt hours of electricity use each month for four months.
When an electric demand meter is used, an electricity provider utilizes the highest kilowatt rate recorded by the meter in order to calculate an electricity bill. The Long Island Power Authority explains that where an electric demand meter is used, a bill will not total less than 70 percent of the highest recorded demand.