An insulator for supporting a high voltage transmission line or other electrical device is provided with an optical fiber extending through the insulator between housings at opposite ends of the array of sheds. The optical fiber, or a plurality of such fibers, can be connected to external fibers in the end housings to form a communication path between a sensor on the electrical device and a ground location or to form a communication link between two ground locations, using a fiber extending along the transmission line as the intermediate portion of the communication link.