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When voltage is impressed across any insulation system, some current leaks into, through, and around the insulation. When testing with dc highvoltage, capacitive charging current, insulation absorption current, insulation leakage current, and by-pass current are all present to some degree. For the purposes of this document on cable fault locating, only leakage current through the insulation will be considered. For shielded cable, insulation is used to limit current leakage between the phase conductor and ground or between two conductors of differing potential. As long as the leakage current does not exceed a specific design limit, the cable is judged good and is able to deliver electrical energy to a load efficiently. Cable insulation may be considered good when leakage current is negligible but since there is no perfect insulator even good insulation allows some small amount of leakage current measured in microamperes.