Wire and cable in a broad sense is also referred to as cable. In a narrower sense, cable refers to insulated cable. It can be defined as a collection of one or more insulated wire cores, together with their respective possible coverings, total protective layer and outer sheath. The cable may also have additional uninsulated conductors.
China's wire and cable products are divided into the following five categories according to their use：
1. bare wire.
2. winding wire.
4. Communication cables and communication fiber optic cables.
5. Electrical equipment with wire and cable.
The basic structure of wire and cable.
1. conductor: the object that conducts the current, wire and cable specifications are expressed in terms of the cross-section of the conductor.
2. Insulation: the outer insulation material according to its degree of withstand voltage.
Working current and calculation.
Electric (cable) cable working current calculation formula.
Single-phase
I=P÷(U×cosΦ)
P - power (W); U - voltage (220V); cosΦ - power factor (0.8); I - phase line current (A).
Three-phase
I=P÷(U×1.732×cosΦ)
P - power (W); U - voltage (380V); cosΦ - power factor (0.8); I - phase line current (A).
Generally, the safety cut-off rate of copper wire is 5-8A/mm2, and that of aluminum wire is 3-5A/mm2.
In the single-phase 220V line, the current per 1KW power is about 4-5A, and in the three-phase circuit with balanced three-phase load, the current per 1KW power is about 2A.
That is to say, in a single-phase circuit, each 1 square millimeter of copper conductor can withstand 1KW power load; a three-phase balanced circuit can withstand 2-2.5KW of power.
But the higher the operating current of the cable, the smaller the safe current per square millimeter can withstand.
Post time: Oct-20-2022