A 35kV line above the phase conductors is typically an Optical Ground Wire (OPGW), serving both as a ground wire and a fiber optic communication cable.

What is an OPGW?

An Optical Ground Wire (OPGW) is a specialized cable installed above high-voltage transmission lines, including 35kV systems, that combines the functions of grounding and telecommunications . The cable contains optical fibers encased in a tubular structure, surrounded by layers of steel and aluminum wires. The conductive outer layers provide lightning protection and grounding, while the optical fibers allow high-speed data transmission for utility communication or third-party use .

Why It's Positioned Above the Phase Lines

The OPGW is installed above the phase conductors to intercept lightning strikes and safely conduct fault currents to the ground, protecting the main power lines from damage . This positioning also minimizes the risk of phase-to-ground faults and ensures system reliability.

Dual Functionality

• Grounding: Acts as a conventional ground wire, bonding towers to earth and shielding the power lines from lightning .
• Communication: Contains optical fibers for high-speed data transmission, supporting utility control systems or leased communication services .

Summary

So, the 35kV line above the phase conductors is not just a standard ground wire; it is an OPGW cable that functions simultaneously as a ground wire and a fiber optic cable, providing both electrical protection and communication capabilities . This dual-purpose design is common in modern high-voltage transmission systems.