The fuse box fulfills an important safety function in our vehicle, as it prevents potential short circuits or excess loads from affecting the conductors of the electrical installation.
Today’s vehicles have complex electrical circuits that are responsible for feeding various mechanisms dependent on the energy provided by the battery, something even more relevant in the case of hybrid cars or electric cars.
The fuse plays a fundamental role in the integrity of this entire electrical network, since it fulfills a basic protection function that we are going to review in depth in the following lines.
What is and what is a fuse for?
The fuse is a metal-based filament or sheet whose main quality is its low melting point. It is placed as an intermediate point in an electrical installation allowing the passage of current so that, If there is a short circuit or an overload in the system, it melts by action of the Joule effect (part of the energy of the electrons is converted into heat when the atoms of the conductive material collide).
When melted, it insulates and protects the rest of the installation, thus avoiding the risk of fire or breakdown of the elements that make up it. Its first uses date back to the 18th century, since then the technology related to the materials used and manufacturing methodologies has advanced considerably.
Types of fuses
There are multiple types of fuses for numerous applications in household appliances, mining facilities, transformers, lighting, heating or railway installations, among many others, but for obvious reasons we will focus on those that are installed in vehicle fuse boxes.
These are detailed in the user manuals for each vehicle, so that the user knows which circuit each of them is assigned to and what type it is in the event of its replacement being necessary. The amperage of each fuse is indicated by a universal color code which we describe below:
- Brown: 5 A (parking sensor, alarm, horn)
- Red: 10 A (lighting, sound system, central locking)
- Blue: 15 A (fuel pump, brake lights, wiper)
- Yellow: 20 A (sunroof, heated seats, cigarette lighter)
- Transparent: 25 A; Green: 30 A; Amber: 40 A (starter, air conditioning, window regulator)
Additionally, depending on their manufacturing material or qualities, we can find the following types of fuses:
- Of lead: already practically disused today, it is made up of a lead wire filament. It is no longer used, as it is very prone to oxidation.
- Diazed: It has a threaded crown that allows the device to be closed and fixed to the base of the circuit by means of screws.
- Cylindrical: it is made of ceramic material, inside which is the filament. Therefore, it is very resistant to shocks and friction.
- Glass encapsulation– Similar to the ceramic cylindrical fuse, it differs in that the lining is made of transparent glass. Thanks to them, it is possible to see if the filament is broken, although it may be somewhat less resistant to shocks.
- Chicote: This type of fuse uses a metal filament, usually lead.
- Screw cap: Generally cylindrical and made of ceramic material, it has a screw cap that allows the fuse to be opened and the damaged filament changed.
- NH fuse: also called blades, it consists of a filament inserted into a casing of structures that will act on the filament in the event of a power surge.
- Pill: It is practically identical to the cylindrical fuse, but it has a different shape.
- Cartridge: made of insulating material, it is integrated into the circuit by pressing on a metal support. It is easily replaceable and is often integrated into small boards and circuits.
How to change a fuse
Replacing a blown fuse is really simple and requires a few steps to do so:
- Locate the fuse box using the vehicle’s user manual (generally to the left of the steering wheel, at the bottom).
- Locate in what position is the fuse in charge of carrying out the operation that has stopped working on the vehicle.
- Take out the damaged fuse with plastic tweezers and replace it with one of the same color and, therefore, amperage.