An abbreviation for earth fault. It refers to an unintended electrical connection between a live conductor and the earth or an earthed metallic frame. Protection relays specifically designed to detect this imbalance and trip the circuit are labeled as EF relays.
Heard on the job
The feeder tripped on an EF alarm right after the lightning strike.
Also heard as
- earth fault
Related terms
Earth fault
Fault in which a live conductor makes unintended contact with earth or with earthed metalwork.
Earthing
The practice of connecting electrical equipment and systems to the general mass of the earth.
Residual-current device
A safety switch that trips a circuit when it detects leakage current to earth.