CIRCUIT PROTECTION - Basic circuits
|Circuit type||Fuse - amps||MCB - amps|
|Radial (up to 20 sq m floor area )||20||20|
|Radial (up to 50 sq m floor area )||30||32|
With the main switch still off, remove the fuse from its carrier and look to see whether it is of the replaceable wire type or cartridge type.
Cartridge or rewireable fuse
It is always as well to keep a selection of cartridge fuses or fuse wire of the appropriate ratings near the consumer unit so that they may easily be found when required.
With any fuse, it is essential that the replacement is of the correct rating. Do not simply rely on replacing it with the same type as was already there. It may not be correct. Use the table to determine which rating is required
The cartridge type have fuses which look similar to those you would find in a standard household plug.
The fuse is removed by pulling it out from between the sprung metal clips. The new one is simply inserted back into the clips.
The rewireable type have a fuse wire held at both ends by a small retaining screw.
Undo both ends and remove the broken wire. Make a ‘U’ shape in the end of the replacement wire and wind it clockwise around one of the retaining screws. Re-fasten the screw. Take the other end of the wire and feed it through to the other screw following the same route that the old wire took. Wind the end clockwise around the screw and fasten it.
Finally, trim off any excess wire so that stray ends will not cause problems.
Insert the fuse back in its carrier on the consumer unit..
Circuit breakers or MCB
With MCBs, simply look to see which one has ‘tripped’ and having remedied the fault which triggered it, reset the button.
Once you are sure that the fault has been rectified, replace the cover of the consumer unit and switch back on. Check that the circuit is now functioning correctly.
If the fuse blows again straight away, the fault has not been rectified and must be dealt with. If you are not sure what the problem is, seek professional help.