Optical Ground Wire (OPGW) is a dual functioning cable. It is designed to replace traditional static / shield / earth wires on overhead transmission lines with the added benefit of containing optical fibers which can be used for telecommunications purposes. It is best suited to applications with moderate to low span ut increasing fibre strain. Because of this, OPGW contains exposed elements made of both. An optical ground wire (also known as an OPGW or, in the IEEE standard, an optical fiber composite overhead ground wire) is a type of cable that is used in overhead power lines. Installed at the top of high-voltage and extra-high-voltage transmission lines, OPGW cables provide lightning.