Lead Alloy Sheaths for Power Cables

It depends on the type of power cable. Are you referring to low pressure, oil-filled underground power cable?

Yes

low pressure, oil-filled underground power cable

The lead sheath contains the oil, which provides electrical insulation. In this type of cable, the insulating medium is oil soaked into a paper wrapping. Each conductor is wrapped in paper to ensure separation from other conductors and the grounded lead sheath. When the oil is pumped into the cable, it soaks into the paper, providing a consistent insulation cross-section. The lead prevents the oil from leaking out. If the paper dries out, the loss of insulation will cause cable failure by short circuit.

Medium voltage cables should have a pressurized oil tank at one or more locations along the cable route. A line from the tank is soldered into the lead sheath to provide extra oil to make up for minor leaks. Monitoring the level in the tank provides early warning of a leak, which can then be located and repaired before the cable fails.