A short circuit is a connection between two or more conductors normally at different voltages, so current flows through a path of far lower impedance than the load. Fault types are three-phase, phase-to-phase, phase-to-phase-to-earth and single-phase-to-earth, and the three-phase case usually gives the highest current used to rate switchgear. Calculations under IEC 60909 or the ANSI methods yield the initial symmetrical, peak and breaking currents.
Excavator went through the cable and put a dead short circuit across two phases, the feeder breaker cleared it in four cycles.
Also heard as
- short
Do not mix it up with
- Earth fault: An earth fault is one particular kind of short circuit, between a live conductor and earth.
Related terms
Fault current
Abnormally high current that flows when insulation fails and a short circuit or earth fault forms.
Earth fault
Fault in which a live conductor makes unintended contact with earth or with earthed metalwork.
Breaking capacity
Highest fault current a circuit breaker or fuse can interrupt safely at its rated voltage.