unit

A unit, in electrical utility accounting, is a single kilowatt-hour (kWh) of energy consumed or generated. It is the standard billing increment on domestic and industrial electricity meters. When a meter dial advances by one complete rotation on its kWh scale, or when a digital meter increments its display by 1, one unit has been recorded. This is the quantity that appears on your power bill and determines your charges.

The term originates from British electrical practice and remains standard in Commonwealth countries and parts of Europe. In North America, the same quantity is usually called simply a kilowatt-hour without the euphemism, though older installations may use unit to mean the same thing. The word unit persists in utility engineering partly because it is shorter to write on billing documents and meter charts, and partly because it preceded the modern SI naming convention.

Metering and Rate Structures

Electricity meters record consumption in units by integrating power draw over time. An electromechanical meter uses a rotating disc; the number of rotations equals units consumed. Digital meters count pulses from a current transformer or solid-state sensor, accumulating kWh values. Utilities charge a fixed price per unit, though many tariffs now tier this rate: cheaper units for baseline consumption, higher rates for excess, or time-varying rates that charge different prices per unit depending on time of day or season.

On an industrial site, large consumers may have separate meters for peak demand and off-peak consumption, with units on each meter priced differently. Some sites also have generation meters that record units fed back to the grid, which reduce the net units billed. Understanding your unit consumption and rate per unit is essential for cost control and energy management decisions.

The unit remains the fundamental currency of the electricity supply chain. Generators sell units wholesale; distributors buy and resell units to domestic and business customers. Because it is a simple, dimensionally consistent quantity (energy, not power), it is the only proper basis for billing and contract accounting in electrical supply.