Fuses Terminology


High Rupturing Capacity – the ability of a fuse link to interrupt high fault currents

Rated Voltage

The maximum voltage the fuse link is designed to interrupt

Current Rating

The value of current a fuse link will carry continuously without deterioration.

Rated breaking capacity

The highest value of current the fuse has been tested to interrupt, typically : 120kA (IEC) & 80kA (BS)

Time current curve of an uninterrupted short circuit



Main fuse types (applications)

gG: for cable protection

gG fuses will blow under overload and short circuit

aM: for motor starter protection

aM fuses will not blow during the current inrush due to the motor start.
aM fuses can not manage overload (overload will be managed by the thermal relay + contactor), only short-circuit.

uR: for power-electronics protection

uR fuse react extremely quickely, so the let-through energy will be greatly reduced.
uR fuse power limitation is unique: hundreds of time better than the best breakers.
uR fuses are the unique protection solution to protect power-electronics (IGBT, etc…)

gPV: for photovoltaic installation

gPV fuses are dedicated to PV installation to protect against reverse current


Main fuse types (per area)

NFC fuses


  • Worldwide, except in USA, UK and Commonwealth
  • Sizes: 10×38, 14×51, 22×58
  • Low ratings (up to 125A)
  • With or without strikers
  • Elastic connection

DIN fuses


  • Worldwide, except in USA, UK and Commonwealth
  • Sizes: 000 to 4
  • Intermediate ratings (up to 1600A)
  • With or without strikers
  • Elastic connection

BS fuses


  • Mainly UK and Commonwealth
  • Sizes: F1 to D1
  • All ratings (up to 1250A)
  • No strikers
  • Bolted connection

UL fuses


  • Mainly USA
  • All ratings (up to 6000A)
  • No strikers
  • Elastic or bolted connection