An OPGW (Optical Ground Wire) is a dual-purpose cable used on high-voltage overhead lines. It's designed to function as a traditional ground wire, shielding the phase conductors from lightning strikes and providing a path for fault currents.

The key difference lies in its core. OPGW cables contain one or more fiber optic tubes embedded within their protective outer metallic strands. This allows the cable to also serve as a high-speed data communications channel for the utility company, supporting applications like SCADA (Supervisory Control and Data Acquisition), remote monitoring, and smart grid communications. This dual functionality eliminates the need for a separate communications line, offering significant cost savings and improved system reliability.