The Difference Between Single-Phase Two-Wire and Single-Phase Three-Wire Electricity Meters
Below, we will explain the differences between the two in detail.
Key Summary:
Single-phase two-wire meter: Corresponds to China's 220V residential electricity system, using a live wire (L) and a neutral wire (N) for power supply.
Single-phase three-wire meter: Corresponds to the 120V/240V electricity system in countries like the United States, using one live wire (L1), one neutral wire (N), and another live wire (L2) for power supply.
Comparison of Single-Phase Two-Wire and Single-Phase Three-Wire Electricity Meters: Among electricity meter types, the single-phase two-wire meter (Chinese standard), also known as a 220V meter, requires only two wires (live wire and neutral wire). The corresponding system voltage is 220V, and the power supply method is to provide 220V between the live and neutral wires. Whether it's high-power equipment like air conditioners and electric water heaters, or low-power equipment like lamps and chargers, they all directly use 220V. It is mainly used in mainland China, Europe, India, and other regions. However, due to the higher voltage, theoretically, the risk of electric shock is slightly higher.
Single-phase three-wire meters (US standard, etc.) are also known as phase-separated meters or 120V/240V meters. They have three wires (live wire L1, neutral wire N, live wire L2), and the system voltage is 120V/240V. There are two power supply methods: L1/N or L2/N provides 120V, and L1/L2 provides 240V. High-power devices (such as electric stoves and dryers) use 240V, while low-power devices (such as lamps and chargers) use 120V. They are mainly used in North America (the United States and Canada), Japan, and Taiwan, where the daily voltage is lower (120V), making them relatively safer.
In China, if you apply for electricity for your household or replace your meter, you will definitely encounter a single-phase two-wire meter (220V). The concept of a "single-phase three-wire meter" is necessary to understand electricity systems in other countries (especially the United States). The fundamental difference between the two lies in the power grid standards and voltage specifications of the respective countries or regions.
