FUSES
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FUSES |
Home | A-Z contents | D.I.Y Forum | Safety First | Disclaimer
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For a electrical installation to be as safe as possible it needs the correct thickness of wire to be used and the correct amperage fuse to be used. If you use a fuse of higher amperage than the circuit is designed for, then the wire could melt and set on fire or the appliance can be seriously damaged
Fuses are rated in Amperes or Amps as they are more commonly known, a fuse is a deliberate weak link in a circuit and will melt if too much current passes through the fuse. There are several different types of fuse but they all do the same thing which is protect the circuit. A fuse will not stop you from being electrocuted! but a fuse can help prevent electrical fires.
As a general rule of thumb fuses are rated by how many watts that circuit is using, 1000 watts is equal to 4 amps so therefore the maximum single appliance size that can be plugged into a socket is 3000 watts, this would be protected by a 13 amp fuse.
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Cartridge fuses are the commonest type of fuse, these are often found in consumer units and domestic electrical plugs. |
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Here a industrial type cartridge fuse is contained in a fuse carrier, this is then inserted into the fuse holder on the consumer unit. |
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This is a picture of the Main fuse in a house, this is owned
by the electricity company and cannot be removed without their permission.
These fuses often have an anti-tamper seal so that the fuse cannot be
removed without cutting off the anti-tamper seal. If you suspect the main fuse has blown then you must contact your electricity provider to have it replaced. |
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Fuse Ratings |
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45 AMP |
For circuits of more than 13kw (13000 w) |
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30 AMP |
For socket ring mains, some cooker and shower circuits up to 7kw (7000 w) |
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20 AMP |
For storage and water heater circuits |
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15 AMP |
For single appliance circuits up to 3kw (3000 w) |
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13 AMP |
For appliances between 700 and 3000w (3kw) |
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5 AMP |
For lighting circuits. The maximum permissible load of a lighting circuit is 1200w or 12* 100 watt lamps |
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3 AMP |
For appliances up to 700 watts, such as table lamps and alarm clocks |
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Fuse Wire |
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Some fuses especially in consumer units do not use cartridge fuses but instead use fuse wire. This is normally held in place at each end of the fuse with a screw. The fuse ratings for cartridge fuses and fuse wire are the same. |
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For detailed instructions for testing and replacing an appliance fuse please click here |
For detailed instructions for testing and replacing a consumer unit fuse please click here |
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