Everything You Need to Know About Car Fuses

blade fuses for cars

What is a Fuse?

A fuse is an electrical component designed as a safety measure to protect from overcurrent of an electrical circuit. Its basic purpose is to break the circuit when the current becomes more than the desired value, thereby preventing possible damage from equipment failures and short circuits. Fuses come in many different shapes and sizes and each one is designed to protect a circuit with a specific set of electrical parameters.

Blade Fuse

Developed in the 1970s, blade fuses or automotive fuses, are typically found within the vehicle’s fuse box. Most blade fuses are designed for 12v electrical systems and are primarily color-coded with the amperage rating written on top.

Amp rating can range from 0.5A to as high as 80A. The rating refers to the maximum amount of amperage the fuse can handle before it fails.

bmw f30 330e fuse diagram

What is a Fuse Box?

A fuse box houses the fuses and relays of an electrical system. In automotive applications, there are usually two fuse boxes. The primary fuse box contains high voltage engine fuses and relays. The secondary fuse box contains fuses and relays to accessories.

Where is my fuse box?

In most vehicles, the fuse box is located under the dashboard on either the driver or passenger side, under the hood, or in the trunk. We recommend referring to your vehicle’s owner manual for the location of your fuse boxes.

Tip: It is important to refer to your vehicle’s fuse box diagram to use the correct amperage and type. Using a different amperage can lead to a short circuit and possible damage to your equipment.

How do Fuses Work?

Fuses are placed in a circuit and act as a electrical safety device by stopping the flow of current in the event of a overcurrent. The two metal blades are encased in a semi-translucent non-combustible housing and is connected by a strip of metal.

The metal strip between the two electrical terminals breaks/melts when too much current flows through it, thus breaking the circuit and stopping the flow of current. When a fuse is blown, the separation of the middle piece will be apparent. A new fuse can be easily replaced in the event of a blown fuse.

Types of Blade Fuse

Blade type fuses are the most commonly used fuse type in automotive applications. Each fuse is color coded with the printed amperage rating on top. They come in several shapes and sizes with the 4 most common being:

  • Micro: Smallest type of blade fuse. Comes in 2 prong micro2 and a 3 prong micro3.

  • Mini (APM, ATM): Smaller than standard sized fuses. Also comes in a low-profile mini version.

  • Standard (APR, ATC, ATO): Found in most cars and trucks.

  • Maxi (APX): Used in heavy duty applications. Available in higher amperage.

blade fuse types graphic
blade fuse for cars