In fact, the sheath can be understood as two or three parallel BV wires, BV wires have insulated rubber, and a layer of rubber covering the three or two parallel parallel BV lines is a sheath.

Sheathed wire is also the most commonly used household wire, usually consisting of three cores or two cores.

As a result of the family decoration now, generally uses the line tube, then uses three copper wires (the fire line, the zero line, the earthing line) passes through the line pipe laying. But the sheath wire is much safer than the ordinary wire, so it is still more useful in home decoration in the construction field. The sheathing line is the power line used before. Before the home decoration, the cover line was used as the lighting and power line; it can be directly embedded in the wall or fixed on the wall. The advantage of it is that it can save the thread pipe or the line groove, and it is replaced by a sheath insulation outside. It is convenient, quick, beautiful and safe to use. It is the best choice to connect the household movable plug board, the refrigerator or the air conditioner.