A shielded electric wire includes one metal pipe and one electric wire having a conductor and an insulator. An outer diameter of the conductor at 25° C. is set as a, a coefficient of linear expansion of the conductor is set as α.sub.a, and a temperature difference between a maximum temperature and 25° C. is set as Δt, an outer diameter a′ of the conductor after thermal expansion is a′=a+α.sub.a×a×Δt, and when a wall thickness of the insulator at 25° C. is set as b and a coefficient of linear expansion of the insulator is set as α.sub.b, an insulator wall thickness b′ after thermal expansion is b′=b+α.sub.b×b×Δt, and an inner diameter c of the one metal pipe is set to satisfy c≥a′+2b′.

A downhole cable includes a central core. The central core includes a metal tube having a plurality of optical fibers therein or a copper wire. The downhole cable further includes an extruded aluminum tube surrounding the central core.

A shielded electric wire includes one metal pipe and one electric wire having a conductor and an insulator. An outer diameter of the conductor at 25° C. is set as a, a coefficient of linear expansion of the conductor is set as α.sub.a, and a temperature difference between a maximum temperature and 25° C. is set as Δt, an outer diameter a′ of the conductor after thermal expansion is a′=a+α.sub.a×a×Δt, and when a wall thickness of the insulator at 25° C. is set as b and a coefficient of linear expansion of the insulator is set as α.sub.b, an insulator wall thickness b′ after thermal expansion is b′=b+α.sub.b×b×Δt, and an inner diameter c of the one metal pipe is set to satisfy c≥a′+2b′.

A downhole cable includes a central core. The central core includes a metal tube having a plurality of optical fibers therein or a copper wire. The downhole cable further includes an extruded aluminum tube surrounding the central core.

A downhole cable includes a central core. The central core includes a metal tube having a plurality of optical fibers therein or a copper wire. The downhole cable further includes an extruded aluminum tube surrounding the central core.

A high-voltage cable (1) comprising a hollow conductor (2), characterized in that an inner tube (3) is arranged inside the hollow conductor (2), and a first electrically insulating layer (4) is arranged between the innertube (3) and the hollow conductor (2), wherein said first electrically insulating layer (4) is in direct contact with the entire outer surface of the inner tube (3) and the entire inner surface of the hollow conductor tube (2), and a method (100) of manufacture of the cable.