What is the difference between the current-carrying capacity and the safe current of wires and cables? ? ?

Safe current is also known as safe flow rate or allowable continuous current. When current flows through wires or cables, the presence of impedance causes energy loss, which heats up the wires and cables and raises their temperature. The greater the current flowing through a wire or cable, the higher its temperature. When the temperature rises to a certain level, it can damage the insulation of wires and cables, accelerate external oxidation, thereby causing leaks, wire breaks, and in severe cases, accidents such as fires. To ensure the safe operation of electrical circuits, the cross-sectional area of all wires and cables must meet the heating requirements; that is, at any ambient temperature, when the wires and cables carry the maximum load current continuously, their temperature must not exceed the maximum allowable temperature (usually around 70°C). The load current under these conditions is referred to as the safe current. The safe current for wires and cables is determined by their type, specifications, ambient temperature, and method of installation, and there are specialized tables available for reference. From this perspective, the safety current seems to be a concept similar to the current-carrying capacity.