This specification prescribes the function and performance criteria, and acceptance testing for electrically insulating aprons for the protection of workers from incidental contact with live electrical apparatus or circuits. Three types of aprons are provided and are designated as follows: Type I, made from properly vulcanized high-grade cis-1,4-polyisoprene rubber compound of natural or synthetic origin that are non-resistant to ozone; Type II, made of any elastomer or combination of elastomeric compounds that are resistant to ozone; and Type III, made of any combination of elastomer and thermoplastic polymers that are elastic in nature and resistant to ozone. Six classes of insulating aprons, designated as Class 00, 0, 1, 2, 3, and 4, are assigned according to electrical characteristics. Aprons shall be tested for their conformance with specified chemical, physical, and electrical requirements.