The fuse box is responsible for many things such as your car radio, dashcams and reverse cameras. You may have previously been in a situation where you have been driving your car and your radio suddenly quits. Before panicking and thinking it’s your car battery losing charge, check your fuses.  Fuses are used to protect certain components by limiting the electrical current flowing through wires.

What is a car fuse?

Car fuses are components that protect electrical wiring in cars and other vehicles. They protect against overcurrent and short-circuiting by disconnecting the circuit if a harmful level of current is detected. There are a variety of types and sizes available, each suited to specific purposes and electrical equipment in a vehicle.

How do fuse boxes work?

To protect electrical circuits against overload or short circuit, an automotive fuse box has a series of fuses, relays, and diodes. The battery powers the fuse box directly. Here is what each component is and what it does:


The fuse's primary function is to protect the wiring. Fuses should be sized and placed in such a way that they safeguard the wire to which they are connected. For example, the radio will suddenly stop working if it pulls enough current to blow the fuse. The fuse protects the wire, and subsequently the radio, which is significantly more difficult (and expensive) to replace than the fuse.

A wire conductor in the fuse breaks when the current exceeds the ampere limit. The ampere limit, as well as different colour codes, are printed on each fuse. It is critical to use the correct fuse with the correct ampere for safety.


A relay can be thought of as an electric lever: turn it on with a small current, and it activates another appliance that uses a much bigger current.

An electromagnet is the heart of a relay (a coil of wire that becomes a temporary magnet when electricity flows through it).


Diodes are frequently used in conjunction with relays to allow direct current to flow in just one direction.

Are there different types of car fuse?

Blade fuses are the most commonly found fuses in cars and have variable amperes. There are six different variations available:

  •  Micro2 (5-30 amp)
  • Micro3 (5-15 amp)
  • Mini and Low Mini (2-30 amp)
  • Regular ATO/ATC (1-40 amp)
  • Maxi Heavy Duty (20-100 amp)

How do you wire a fuse box in your car?

Knowing how to wire a car fuse box is important in many situations, especially when adding new electrical components to your vehicle. In a car, there are two major fuse box locations: one near the steering wheel and the other beneath the bonnet.

Not sure how to wire a fuse box in a car? No problem, we’ve got you covered. Read on for a step-by-step guide but remember, if in doubt, visit your local mechanic for guidance.

Step 1: safety measures

First and foremost, take all necessary precautions before working on your car's electrical system. Disconnect the batteries from the car fuse box and be cautious of any sharp edges that could cause injury.

Step 2: start the process

Most of the time, the car fuse box is located near the battery. Clean the wires first with the wire brush and disconnect the negative battery cable. Unclip the safe box to disconnect it and pull the locking tab out by depressing it. You can then remove the fuse box's lid.

A diagram with all the fuse placements may be found on the cover. Alternatively, this is where your owner's manual comes in handy, as it contains the exact electrical diagrams required to properly connect the wires.

Step 3: connect a wire to a fuse box

Wondering how to connect a wire to a fuse box? Well, you'll have a clear reference on where to plug the cables thanks to the diagram on the cover and the diagram in the owner's manual. Most wires are colour-coded to assist you in locating each wire, and you can also follow the lead.

Step 4: put it all back together

Replace the car fuse box and reconnect it to the battery after everything is finished. Be prepared to spend some time without being rushed as the wiring process can take up to an hour on average.

How much does it cost to replace a car fuse box?

The average cost of replacing a fuse box with a circuit breaker is £535 at a garage. This price is calculated on a number of factors: £75 for the old fuse box to be removed, £300 for the new fuse box, and £160 for labour. However, doing this work yourself can save money.

If your box or unit has a faulty circuit breaker, simply replacing the circuit breaker will cost you £52.50, on average.

Drive away with a reliable fuse box today

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