Basically, there are three different types of measurements required for the three different types of meters. One is a single-phase meter which is common in most residential applications. This typically has one voltage and one current to be measured, and it supports low to medium load. A dual phase meter, which is not so common worldwide, used mainly in Japan, has two voltages and two currents to be measured. Each phase is off by 180º, and it is typically for medium to large loads. Finally, three-phase measurements are commonly used for large office space and industrial applications. There are three different phases that are 120º out of phase with each other. Three voltages and three currents need to be measured, so a minimum of six Sigma Delta ADCs are needed. The three-phase meters are typically designed for application in large loads. Typical parameters to be measured are: energy, which is active, reactive, and apparent; power, which is active, reactive, apparent; power factor; voltage and current; frequency; temperature; tamper detection; and energy pulse output for calibration of the meter.