Replacing a mains fuse

You can replace a mains fuse yourself by following these instructions.

To replace a mains fuse you will need:

  • a torch
  • a screwdriver with an insulated handle
  • fuse wire or cartridge fuse of the correct rating
  • a step ladder.

How to replace a mains fuse

  • Flip the mains switch on the 'consumer unit' so that 'OFF' is showing.
  • Unplug all appliances.
  • Unscrew the cover to the fuses on the consumer unit.
  • Pull out each fuse holder to check which has blown.If it is a re-wireable fuse, remove any remaining old wire and feed new wire through the holder, around the retaining screws at each end and screw up tightly at both ends.If it is a cartridge fuse, take out the old cartridge and fit a new one into the holding clips.
  • Flip the mains switch on the consumer unit so that 'ON' is showing and check all circuits are working.
  • Plug in each appliance one at a time to check if any of them are faulty. If an appliance is faulty it will blow the fuse again.

General advice

The fuse box or consumer unit is next to the electricity meters. Fuses usually blow because either an appliance is overloaded or an appliance is faulty.

Always replace the cartridge or fuse wire with one of the correct rating. As a general rule:

  • 5amp (A) cartridges and fuses are for lights
  • 20A are for immersion heaters
  • 30A are for sockets and the cooker (in some cases the cooker cartridge will be 45A).
  • Mark the name of each circuit on the inside of the fuse and on the cover to help identify fuse circuits.

Never tamper with the Electricity Board's fuses and seals.