Metallic armors are placed on underwater power cables to provide mechanical protection to the underlying lead sheath. Usually the armor of multi-conductor cable consists of galvanized steel wire spirally wrapped over a bedding of impregnated jute which has been placed over the lead sheath of the cable. This type of armor has proved to be of value in protecting the lead mechanically. It also has been useful from the corrosion standpoint.
When high voltage circuits capable of carrying large amounts of power are installed they are constructed of single conductor cables laid parallel to each other. The use of steel or other magnetic material as armor on single conductor cables is undesirable inasmuch as the electrical losses due to induced currents are high and the current carrying capacity of the cables is adversely affected. Under these circumstances a non-magnetic material having good electrical conductivity is preferred. Aluminum offers these properties....
