Multi-core cable

A multi-core cable, comprising:

• a heat detection line comprising a twisted pair wire comprising a pair of heat detecting wires being twisted together, each heat detecting wire comprising a first conductor and a first insulator covering a periphery of the first conductor, wherein the heat detection line further includes a jacket including a plurality of layers of insulating resin around the twisted pair wire and a reinforcing layer covering around the jacket;
• a plurality of electric wires spirally twisted around the heat detection line, each electric wire comprising a second conductor and a second insulator covering a periphery of the second conductor, wherein a thickness of the second insulator is half (½) or more and 1 time or less an outer diameter of each strand constituting the second conductor;
• and
• a sheath covering the heat detection line and the plurality of electric wires together,
• wherein a melting point of the first insulator is lower than a melting point of the second insulator,
• wherein the second conductor has a shape in a cross-section perpendicular to a cable longitudinal direction in which a width along a circumferential direction is gradually increased from a radially inward portion to a radially outward portion, and
• wherein outer surfaces of the electric wires are in contact with an outer surface of the reinforcing layer.