The purpose of an automotive fuse is to break the circuit if it becomes overloaded. The excessive heat generated when something draws too much current could set the whole vehicle alight! A fuse provides an easily replaceable weak link which will melt before your wiring, or your whole car does.

But which fuse to use? I don’t blame you for finding this a little complicated with so many varieties on the shelf! Choosing the right fuse is essential for your safety, and the operation of your car.

Different Fuse Sizes & Shapes

• Glass fuses Why use a glass fuse? Well, these were the norm for many years as they are cheap and easy. However, they aren’t colour coded like the many varieties of blade fuse, so the amperage is harder to pick at a glance. Audio installations use a large type of glass fuse capable of carrying higher current. Other than this exception; use a glass fuse if that is what your car is equipped with as standard.
• Ceramic fuses are similar to glass fuses, but less common. The fuse wire is external to the body of the fuse, rather than inside a housing.
• Blade fuses are available in a range of sizes, but their colour coding is the same. The first on the scene was the standard blade fuse, followed by the mini blade fuse, then the micro blade fuse, and maxi blade fuse in there too. Blade fuses became smaller as more electronics came into cars, hence more fuses needed to be packed into the same space.
• Fusible links are designed for very high amp ratings and are bolted in place, usually in a fuse box under the bonnet.

Selecting the Right Fuse for the Job

• Glass fuses can be used in an aftermarket installation using a glass fuse holder. However, blade fuses are more popular for this purpose, unless it’s an audio installation. To replace a glass fuse, you can look underneath the lid of your fuse holder for the amperage number and match it up. Or; look closely at the metal end cap of your fuse where the number will be stamped.
• Replacing a ceramic fuse is just as simple. Again, check the fuse holder lid for the correct rating. Ceramic fuses are also colour coded, so you can match them by colour; or find the rating stamped on the fuse.
• Blade fuses are colour coded too; making choosing the correct blade fuse very easy. Blade fuse size differences are very obvious, you should be able to pick the correct size by eye. However; some of the colours used are very similar, so check the top of the blade fuse where you’ll find the amperage stamped - and ensure it matches.
• Fusible links are also colour coded, and have the amperage stamped on the top. Take note of size, shape and fittings on a fusible link; there are a few different sizes, and some have male or female terminals on them.

Taking what you’ve learned here, you should have an understanding of the fuse type you should use. But how do you pick the right amperage? First, discover how much your accessory will draw. This is usually printed in the instructions or on the packaging. Choose a fuse which is 25% higher than this rating, but ensure the fuse is not rated higher than the wire it is installed upon.

Vehicle electronics can be complicated, but having learned a little about fuses; one aspect of it just became simpler.