Illegal tapping is the unauthorized connection of a load to a power line so electricity is drawn outside the utility’s billing system. It is a form of non-technical loss: the power is consumed, but it is not properly metered, recorded, or paid for. In distribution networks, tapping may bypass a meter, splice into a feeder, or connect downstream of a service drop, making the theft hard to see from ordinary billing records.
It matters in cyber security because modern grids depend on trustworthy measurement and control. If meter data, feeder telemetry, or inspection workflows are weak, illegal tapping can hide inside the larger stream of operational data. Defenses include tamper-resistant meters, feeder-level monitoring, anomaly detection, periodic field inspections, and strong identity and access controls for metering systems. In a cyber-physical attack, the same techniques used to conceal illegal tapping can also be used to mask sabotage or fraud, so integrity of telemetry is as important as physical security.