The outer material strengthens and stiffens the cable. The low thermal expansion coefficient of the composites constrains the temperature-related expansion and contraction of the aluminum. With conductivity approaching that of copper, composite-wrapped pure aluminum carries significantly more electrical current than conventional cables with the same mechanical stability. According to McCombs, Composite Power's cables will do more than carry electricity. They will also sense trouble along the transmission line through a glass fiber optic wire running through their center.
Optical fibers monitor the line continuously for hot spots and damage.
He plans to use some of that capacity for a separate line of business by running telephone conversations through them. According to this part of the scheme, Composite Power will install antennas in every tenth transmission tower and run a supplemental cellular telephone network through them. Because the tower materials are transparent to cellular transmissions, the structures can house the antennas within their hollow hexagonal bodies. McCombs speculates that his first customers could be railroad crews that want to use cellular phones in remote areas of the country. Composites also allow for more flexibility in power line construction and configuration because of the material's mechanical properties and its ability to insulate electricity.