Submarine power cables in the United States are frequently made with rubber insulation for voltages up to 35 kV phase-to-phase. The choice of rubber rather than oil-impregnated paper, and the elimination of the lead sheath, is usually governed by physical and chemical conditions rather than cost.The type of rubber insulation preferred is “oil base”, an ozone-resisting compound having good electrical stability when exposed to water, heat and high voltage.The advantages of the longitudinal-strip method of insulation are described, together with details of tests, strand shielding and thermal problems.