This specification covers the acceptance testing of insulating rubber blankets that are used for the personal protection of workers from accidental contact with live electrical conductors, apparatus, or circuits. Two types of blankets, differing in chemical and physical characteristics, are provided and are designated as: Type I, made from properly vulcanized high-grade cis-1,4-polyisoprene rubber compound of natural or synthetic origin that is non-resistant to ozone; and Type II, made of any elastomer or combination of elastomeric compounds that is resistant to ozone. Five classes of blankets, designated as Classes 0, 1, 2, 3, and 4, are assigned according to electrical protection characteristics. Styles of blankets are designated in accordance to construction characteristics, namely: Style A, blankets free of any reinforcements; and Style B, blankets incorporated with reinforcement(s). When evaluated in accordance with the test procedures detailed herein, the blankets shall adhere to the following property requirements: electrical properties such as phase-phase maximum use voltage, AC and DC proof-test voltages, AC and DC dielectric breakdown test voltages, and AC and DC clearances; and physical and chemical properties such as ozone resistance, moisture absorption, tensile strength, tension set, elongation, drape stiffness, flex stiffness, tear resistance, resistance to accelerated heat aging, and puncture resistance.