proper connections
there are many ways to connect electrical conductors: plugs.receptacles,screw terminals,wire nuts,and other special fasteners.For assembled connections,the screws or other fasteners are tightened to be sure that the conductors make good contact with each other.In some cases,codes specify the force or torque required for a connection because later vibration,corrosion,creep of materials,damage,and other factors may reduce the connecting force,thereby reducing the contact area between conductors or between a conductor and a fastener.Unless the connections are tight and stay that way,contact areas get smaller and current density increases,resulting in a connection heating up and even glowing.In some applications, one should inspect connections from time to time to ensure that are tight and in good condition
as noted in chapter 10,one problem with aluminum wire that was used in the late 1970s was creep.An additional problem concerns corrosion.In contrast to copper oxide,aluminum oxide is not a good conductor. as aluminum wire corrodes,aluminum oxide form on the outside of the wire, and resistances,producing more heat and accelerating corrosion.This problem may lead to fire.