OPGW is a dual purpose cable that provides a communications path while also acting as a traditional shield wire on overhead transmission lines. OPAC cables can be installed on existing ground wires or phase conductors, even OPGW or OPCC to expand communications capacity. The cable is called optical power attached cable (OPAC), and it is lashed to the power cable with a specialized tool that is pulled from the ground, such as a cable lasher. Lengths of 2. To determine the power budget and power margin needed for fiber-optic connections, you need to understand how signal loss, attenuation, and dispersion affect transmission. OPGW is a. Fiber Optic Sensing technology enables transmission systems operators to monitor thousands of kilometers of overhead power lines accurately and in real-time.