In electrical engineering, an electrical isolation test is a direct current (DC) or alternating current (AC) resistance test that is performed on sub-systems of an electronic system to verify that a specified level of isolation resistance is met.
[1] The test often reveals problems that occurred during assembly, such as defective components, improper component placement, and insulator defects that may cause inadvertent shorting or grounding to chassis, in turn, compromising electrical circuit quality and product safety.
[2] Isolation resistance measurements may be achieved using a high input impedance ohmmeter, digital multimeter (DMM) or current-limited Hipot test instrument.
The selected equipment should not over-stress sensitive electronic components comprising the subsystem.
A minimum acceptable resistance value is usually specified (typically in the mega ohm (MΩ) range per circuit tested).