Electrical wire insulation resists the flow of electrical charge, thus preventing the loss of electric current and creating a safe vehicle for the flow of electricity. There are a number of materials ...
Any wire that has a coating which is gas and oil resistent,and has a 90c rating for heat it will be exposed to.Thwn ortffn and size is #16-#18 for most auto wire except items which use larger size as ac ,alternator, and any motor controlled system