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ITGlossary · Protection and installation
Ground Fault
An unintended flow of current from a live conductor to earth or to a device’s metal casing.
Technical level:Intermediate
It happens when a live conductor comes into contact with the metal casing of a device, the earth conductor or the ground, usually because of worn insulation, moisture or a poor connection. If the earthing is sound, the leakage current trips the residual current device (RCD); if not, the casing can become live and cause an electric shock.
UPS units and their filters inherently have a small leakage current to earth. When many devices share the same circuit, these currents add up and can trip a 30 mA RCD without any real fault.
Never remove the earth connection to stop the RCD from tripping. Ask an electrician to measure the leakage and choose a suitable device, or to split the loads across more circuits.
Related terms
- Short CircuitAn unintended low-resistance connection between conductors that causes a sudden, dangerous surge of current.
- IK Rating (Impact Protection)Scale from IK00 to IK10 under IEC 62262 that shows how much impact energy the enclosure of an electrical device can withstand.
- Circuit ProtectionDevices such as fuses and circuit breakers that open the circuit on overcurrent or short circuit to prevent damage.
- Operating Temperature and Humidity RangeThe limits of room temperature and relative humidity within which a device is designed to operate correctly.
- Overcurrent ProtectionA system designed to interrupt excessive current to protect UPS and loads.
- Surge ProtectorA device that limits brief voltage spikes from lightning or grid switching by diverting the excess energy to earth.