For retrofit units, a typical electric submetering system uses a solid state meter installed at the distribution point of electrical feeds for each unit. The feeds will generally be found in a breaker panel in each unit or in a central distribution panel. The measurement of electrical usage for each unit is achieved by connecting “current transformers” around each feed to measure the current in each electrical feed. The electric submeter, which also measures the voltage of each specific feed, calculates the kilowatt hours (kWh) of energy by a formula using the current and voltage measurements. Once again, these meters readily connect to a standard wireless transmitter. New construction will in almost all cases use a standard socketed, (bubble) electric meter provided by the utility source.