Refers to the wire model specification. Generally speaking, 4 square meters or 4 square meters means that the cross-sectional area of ??the wire is 4, and the unit is square millimeters. It represents the thickness of the wire. The higher the power, the thicker the wire used by the electrical appliance.
In fact, the so-called "square" or "square" does not refer to square meters, but square millimeters.
The copper wire and aluminum wire in the middle of the wire are circular, and the cross-sectional area of ??these circles is expressed in squares.
Example:
For example, for a 2.5 square wire, its diameter is 1.78mm, then its radius is 0.89mm, and its cross-sectional area is: 0.89*0.89*3.14, which is approximately equal to 2.5 Square millimeters, so it is called a 2.5 square wire.