A multi-core cable is provided with a heat detection line including a twisted pair wire having a pair of heat detecting wires being twisted together, a plurality of electric wires spirally twisted around the heat detection line, and a sheath covering the heat detection line and the plurality of electric wires together. Each heat detecting wire includes a first conductor and a first insulator covering around the first conductor, and a jacket covers around the twisted pair wire. Each electric wire includes a second conductor and a second insulator covering around the second conductor. The jacket includes an inner layer, an outer layer, and an intermediate layer provided between the inner layer and the outer layer, and a hardness of the outer layer is higher than a hardness of the inner layer.

A multi-core cable is provided with a heat detection line including a twisted pair wire having a pair of heat detecting wires being twisted together, a plurality of electric wires spirally twisted around the heat detection line, and a sheath covering the heat detection line and the plurality of electric wires together. Each heat detecting wire includes a first conductor and a first insulator covering around the first conductor, and a jacket covers around the twisted pair wire. Each electric wire includes a second conductor and a second insulator covering around the second conductor. The jacket includes an inner layer, an outer layer, and an intermediate layer provided between the inner layer and the outer layer, and a hardness of the outer layer is higher than a hardness of the inner layer.

An apparatus has a flexible elongated body, a plurality of cables extending in the body along a lengthwise direction, and a first connection assembly on a longitudinally first end of the body connecting to the plurality of cables. Each of the plurality of cables comprises a plurality of wires for transmitting signals and/or power to the first connection assembly.

A standard for near end crosstalk of a category 6A cable, including a registered jack 45 (RJ45), a clamp connected to the RJ45, a first attenuator and a second attenuator. The RJ45 includes a first signal twisted pair to transmit a first source signal and a second source signal, and a second signal twisted pair to transmit a third source signal and a fourth source signal. The clamp includes a first signal pair connector electrically connected to the first signal twisted pair, a second signal pair connector electrically connected to the second signal twisted pair, a first differential amplification circuit and a second differential amplification circuit. The first attenuator is electrically connected to the first signal pair connector. The second attenuator is electrically connected to the second signal pair connector. The second attenuator and the first attenuator are configured to detect the near end crosstalk.

A communication cable includes: a twisted wire obtained by twisting two insulated electric wires each having a conductor cross-sectional area of 0.13 to 0.35 sq; and a sheath configured to coat an outer periphery of the twisted wire, wherein a twist pitch of the twisted wire is within a range from 25 to 37.5 mm. A characteristic impedance is preferably 10010 .

A communication cable includes: a twisted wire obtained by twisting two insulated electric wires each having a conductor cross-sectional area of 0.13 to 0.35 sq; and a sheath configured to coat an outer periphery of the twisted wire, wherein a twist pitch of the twisted wire is within a range from 25 to 37.5 mm. A characteristic impedance is preferably 10010 .