When laying wires, electrical and thermal personnel should use solder to weld the joints of wires firmly. Why?

For conductivity! There is also anti-corrosion! Generally, this kind of welding is used on copper single wire! Because the copper wire of copper single wire is too thick and hard, it is easy to loosen if you want to cover the joint! Once loosened or oxidized for a long time! It will form an air strike at the joint and cause an arc! The arc slowly melts the metal in the arc by electric spark! The distance that leads to bad contact points is getting bigger and bigger! The electric spark is getting bigger and bigger! Frequently mentioned fires caused by electricity, except for electric heating appliances, almost 90% are caused by poorly contacted electric sparks!