Leakage current is the unintended flow of electrical current from live parts to ground or conductive enclosures through the surrounding insulation. Even perfect insulators have some finite resistance and capacitance, allowing microamps or milliamps to pass. Excessive leakage trips residual current devices and indicates degrading insulation.
The RCD keeps nuisance tripping because the combined leakage current of all these switching power supplies exceeds 30 milliamps.
Measuring leakage current over time is a primary way to track the health of cable insulation before a catastrophic failure occurs.
Do not mix it up with
- Fault current: Leakage current flows during normal operation, while fault current is a massive flow caused by an insulation breakdown.
Related terms
Insulation resistance test
DC test that applies a high voltage between conductors and earth and reads leakage resistance in megohms.
RCD
Residual current device: trips when the current going out on the live conductors does not all come back.
Earth fault
Fault in which a live conductor makes unintended contact with earth or with earthed metalwork.
Touch voltage
Voltage a person bridges between a hand on faulted metalwork and their feet or other hand during a fault.