Some customers buy power at a transmission, subtransmission, or distribution voltage. The utility uses _________ for revenue metering.

• A. Primary metering
• B. Transformer metering
• C. Demand metering
• D. Self-contained metering

Answer: (A)

When customers take service at transmission, subtransmission, or distribution voltages, revenue metering is placed on the high-voltage side of the service, which is called primary metering. This setup measures the energy flowing into the customer's point of delivery directly on the line, often using instrument transformers to scale current and voltage to the meter’s range. The main advantage is accuracy and avoiding the uncertainty of transformer losses affecting the bill, since the measurement reflects energy delivered before any downstream transformation. Transformer metering, by contrast, would measure after the voltage is stepped down, introducing additional transformer losses into the measurement and is typically used for lower-voltage services. Self-contained metering is generally for smaller, low-voltage services where the meter contains its own internal sensing elements, and demand metering describes how the load is measured over intervals rather than where it’s placed.