This specification covers the manufacture, testing, and standard requirements of four types of electrical insulating tape consisting of a polyester plastic film coated on one side with a pressure-sensitive adhesive. Besides differences in nominal thickness, Type 1 is a general-purpose tape coated with a thermoplastic adhesive that is not chemically heat reactive, while Types 2, 3, and 4 are general-purpose tapes coated with a heat-reactive thermosetting adhesive. The tapes shall be tested accordingly and consequently conform to standard widths, lengths, and thicknesses, and other specific properties such as elongation, penetraction, high-humidity insulation resistance (measure of corrosion), strain relief (shrinkage), breaking strength, dielectric breakdown, and adhesion to steel and backing.