1.1 This specification covers two (2) types of electrical system insulation monitoring devices. 1.1.1 Type I is an ac device intended as a permanently installed unit for use in the detection of ohmic insulation faults to ground in active ac ungr This specification covers insulation monitoring devices for shipboard electrical systems. Materials covered by this specification include Type I (ac device) and Type II (dc device) electrical system insulation monitoring devices used in the detection o