What is a Fuse?

A fuse is a basic electrical safety device that is widely used in electrical circuits for overcurrent protection. Overcurrent means that the current flowing through the circuit is higher than it should be, which can cause damage to the wires and devices connected to it. A fuse is designed to 'blow', or break the circuit when the current exceeds a certain level, called the current rating. This stops the current flow and prevents heat damage, fire, and potentially electrocution.

Why Do We Need Fuses?

Fuses are essential for protecting our electrical appliances and equipment from damage caused by power fluctuations, short circuits, configuration faults, electrical arcs, and other issues. These can cause excess current to surge through the circuit, which can generate enough heat to melt cable insulation or even start a fire. Fuses act as weak links that break before any serious damage occurs.

What are the Different Types of Fuses?

There are many different types of fuses available for various applications and purposes. Some of the most common ones are:

- Plug fuses (BS 1362): These are fuses that are fitted inside plugs of electrical appliances and tools. They are usually 3 amp or 13 amp fuses, depending on the power rating of the device. For example, lamps, TVs, and electronics usually use 3 amp fuses, while washing machines, kettles, and toasters usually use 13 amp fuses.   
- Cartridge fuses: These are cylindrical fuses that are inserted into fuse holders or sockets. They are often used as incoming protective devices for an entire domestic property in the UK, and found near the electric meter.   
- Fuse wire: This is a thin wire that is wrapped around a ceramic or metal holder. It is used to replace blown fuses in older fuse boxes that do not have cartridge fuses. And if you're still using a fuse box with rewireable fuses, you need to call an electrician to get a fuse box upgrade!  
- Switch fuse units: These are devices that combine a switch and a fuse in one unit. They are used to distribute current and protect cables and devices from overcurrent. We fit these for sheds, garages and outbuildings such as summerhouses.

How Do I Know if a Fuse Has Blown?

There are several ways to tell if a fuse has blown or not. Some of them are:

- Visual inspection: You can look at the fuse and see if there is any visible damage or signs of melting or burning. For plug fuses, you can't usually see if the fuse wire is intact or broken. For cartridge fuses, you can pull out the fuse and check if there is a gap or a hole in the metal strip inside. For fuse wire, you can check if the wire is snapped or melted.   
- Multimeter test: You can use a multimeter to measure the resistance or continuity of the fuse. A good fuse should have low resistance or show continuity, while a blown fuse should have high resistance or show no continuity.   
- Replacement test: You can replace the suspected fuse with a new one of the same current rating and see if the circuit works again. If it does, then the old fuse was blown. If it doesn't, then there may be another problem with the circuit.

How Do I Replace a Fuse?

Replacing a fuse is usually a simple and quick process, but you need to make sure you follow some safety precautions:

- Turn off the power supply to the circuit before touching any wires or fuses.   
- Use only compatible fuses with the correct current rating for your device or circuit.   
- Do not use anything other than a fuse as a substitute, such as foil, paper clips, nails, etc.   
- Dispose of blown fuses safely and keep them away from children and pets.

To replace a plug fuse, you need to:

- Unscrew the plug cover and remove it.   
- Locate the fuse holder and pull out the old fuse.   
- Insert a new fuse of the same current rating into the holder.   
- Screw back the plug cover and plug in your device.

To replace a cartridge fuse, you need to:

- Locate the fuse box or consumer unit and identify the circuit you want to work on.   
- Turn off the main switch or RCD that controls the power supply to that circuit.   
- Pull out the old cartridge fuse from its holder or socket.   
- Insert a new cartridge fuse of the same current rating into its holder or socket.   
- Turn on the main switch or RCD and check if your circuit works.

To replace a fuse wire, you need to:

- Locate the old fuse box and identify the circuit you want to work on.   
- Turn off the main switch that controls the power supply to that circuit.   
- Unscrew the cover of the fuse holder and remove it.   
- Cut off a piece of new fuse wire of the same current rating as your circuit.   
- Wrap it around both terminals of the holder and tighten them with pliers.   
- Screw back the cover of the holder and turn on your main switch.

Please remember, electricity can be dangerous and works done on electrical installations and electrical products should be done so by a competent person, such as your registered electricians serving Medway & Maidstone!

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