Abstract: To provide a sheath structure assembly coupling structure and a sheath structure assembly coupling method, with which excellent workability and a reduction in costs can be achieved; a reduction in the strength of the connection portion or in the electrical connection can be prevented and a uniform and excellent electrical connection can be achieved; with which excellent durability is maintained for a long period even in the usage environment in which a great force such a tension or the like continuously acts; and with which break or a reduction in insulating performance can be avoided.

Abstract: To provide a sheath structure assembly coupling structure and a sheath structure assembly coupling method, with which excellent workability and a reduction in costs can be achieved; a reduction in the strength of the connection portion or in the electrical connection can be prevented and a uniform and excellent electrical connection, can be achieved; with which excellent durability is maintained for a long period even in the usage environment in which a great force such a tension or the like continuously acts; and with which break or a reduction in insulating performance can be avoided.

Abstract: Provided is a wire connection structure for a three-phase sheath type heater that enables to maintain insulation properties, electrical safety, and reliability, without damaging a wire connection portion, even if an installation location is a high-temperature, high-pressure environment, and enables to flow a large electric current, while suppressing the production cost. A canister 2 made of metal is disposed on the distal end side of three sheath type heating elements 10 in a state that a distal end of each of the sheath type heating elements 10 is inserted through a bottom plate 20. A wire connection plate 3 made of metal is disposed in the canister 2 for star-connection. Distal ends of core wires 11 of the sheath type heating elements 10 are joined to the wire connection plate 3 by welding. An insulating material 4 is compressively filled in the remaining space of the canister.