A second insulated conductor is wrapped on top of the foil in the opposite direction. This is called a choke or drain. The drain is wrapped at the same angle as the foil.
The choke assists in canceling the magnetic fields of any induced current (strike) near the LRC. If you can remove the magnetic fields you greatly impede the flow of current down the cable.
This results in “localizing” effect on the cable. In other words, if the cable was connected to a number of light fixtures and lightning struck a fixture, the energy would stay there and not run down the cable. This effect has been proven in government field tests.