Fuses: Why They Are Important

In terms of car audio, most people still do not understand the importance of fuses, what the true purpose of a fuse is, and why fuses are a necessity when installing aftermarket amplifiers in a vehicle. 

The intention of this post is to give you some basic knowledge in regard to fuses and to hopefully help you understand why fuses must be used and what can happen if you use the incorrect fuse or no fuse at all.

What Does the Fuse Do?

A fuse, when installed correctly, serves one of two purposes in car audio. One, the fuse will protect the power source, which includes the power wire, from damage in the case of a short within the circuit. Two, the fuse can protect your audio equipment from damage if there would happen to be a short, or some other failure, that could possibly allow excessive current to pass through the circuit. 

The basic idea of a fuse, in layman’s terms, is to “take one for the team” if a failure would happen. It is more cost-effective to replace a $3.00 fuse than a new amplifier, or worst-case scenario, a new vehicle because your’s has burned to the ground. 

Fuse Specifications

Fuses have two important specifications to be considered for car audio and 12-volt electronics in general.

• AMPERAGE – Amperage is the strength of the electrical current. It is measured in amperes. When examining a fuse, you will see a bold number printed, or embossed, on it. This number represents the amperage rating of that fuse. For example 30. This number lets you know that this is a 30 amp fuse.
• VOLTAGE – Voltage is the pressure from an electrical circuit’s power source that pushes the current through the circuit. Voltage is measured in volts. In most of all car audio applications, fuse ratings are based on the 12-volt standard. Some care should be taken when choosing certain fuse styles, such as AGU style fuses, as they can be similar in design to higher-voltage fuses.

Fuse Types

There are several fuse types available for the car audio industry. These are the most popular used for car audio applications.

AGU – AGU fuses are typically used for lower amperage car audio systems. They are typically glass or ceramic. The end caps can hold heat, especially when enclosed with the “tube-style” fuse holders.

ATC – ATC fuses are the most common for OEM 12 volt applications. These fuse types are usually found externally of car audio amplifiers. They are typically not used to fuse a power wire from the battery to an amplifier.

Mini ANL – Mini ANL fuses are another popular choice for car audio because of their high amperage capacities and their smaller size than the standard ANL fuse style.

ANL – Full-size ANL fuses are the most popular in the car audio industry. They can be rated for a wide range of amperages, making them perfect for almost all car audio setups. 

What Size Fuse Should You Use?

This answer can vary widely depending on who you ask and it can get very technical and confusing fast. The general, basic answer, for a single amplifier set up, is to simply match the fuse rating of your amplifier. For example, if your amplifier has an external fuse rating of 60 amps, you should use a 60 amps fuse at the battery.

For multiple amplifier setups, you will simply add the fuse ratings of all the amplifiers and choose a fuse that is equal to, or slightly higher, than your total amperage your amplifiers are rated at fuse-wise. 

If your amplifiers have no external fuses to estimate the fuse rating, you may need to check the amp’s manual or contact the manufacturer for the correct fuse rating for the model amplifier you have. 

NOTE: If you have to raise the amperage rating of your fuse, a maximum of 5 amps is acceptable. I would not recommend any fuse higher than 5 amps over your calculated fuse ratings for safety reasons. Also, you must be sure your power wire is the correct gauge for the fuse rating. The fuse should match or be slightly lower than the maximum amperage rating of your power wire.

Suggest (MAXIMUM) Fuse Ratings for Corresponding Wire Sizes

Fuse Problems

Melting Fuses

Why is my fuse melting? This is one of the most common questions asked about car audio fuses and the answer can be a few things. Here I will go over the three causes that I have personally run into. The most common cause is a bad ground. A bad ground can cause a lot of different issues, but melted fuses in a common one. Be sure to check your amplifier’s ground wire and grounding point. You can check my previous post about “How To Install Amplifier Wiring Kit” to get some insight on how to properly ground your amplifier. 

Another cause of melted fuses is bad connections to the amplifier. Check the power wire connection at the amplifier. If there are stray strands of wire sticking out of the terminal, this can cause a bad connection and added resistance to the electrical circuit. Make sure your wire connections are proper. Use ferrules on your wires to avoid strands escaping the power connections.

The third reason I’ll go over is cheap fuses and fuse holders. Cheap fuses may be inferiorly made and may cause added resistance which will cause them to overheat and melt. Also, cheap fuse holders can also cause bad connections between the power wire and holder itself and possibly the holder’s terminals and the fuse. This can cause overheating as well. When choosing your fuses and fuse holders, don’t cheap out. Get good quality components. That little extra money now will save that $1500 amplifier you just installed.

Blown Fuses

A blown fuse can be a good thing. That’s what they are supposed to do. But, on the other hand, if you have been running your system for a while, with no problems, and all of sudden you blow a fuse and replace it with the same fuse and it blows again, please DO NOT replace it with a larger fuse. Think about it. If you had no issue with the other fuse before, but now you’re blowing them, one right after the other, something else is going on. Something is malfunctioning. Check your amplifiers and everything else in between, from your alternator, battery, wire, etc. There is another issue going on besides the fuse. The fuse is actually doing what it was designed to do. Fix the main issue, then replace the fuse with the correct fuse and bang on. Don’t play around when it comes to the electrical system in your vehicle. You could burn it down, trust me, I’ve witnessed it.

I Live That #NOFUSELIFE

Bad idea overall. If you are using no fuses at all, you are definitely asking for trouble. There is absolutely nothing to protect your car audio system or your vehicle if a malfunction would arise that would cause a shortage of your electrical system. I have to advise you to rethink your reasoning for not running a fuse inline with your amplifier’s power wiring. It’s not only a good way to save your property, but it’s also a safety measure as well. Get that correct fuse installed. You’ll thank me later.

Conclusion

I hope this post has provided you with some general information about fuses and why they are such an important part of your car audio install.

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DISCLAIMERS:

** Please note that this article provides general information about fuses and their application in a car audio system. Keep in mind that not all vehicles are the same and may require different installation methods and techniques to ensure a safe and effective install. By no means, am I a professional mechanic, and D4S and I, are not liable for any damages caused to your person or vehicle by following these instructions. Please consult a professional if you have any questions or concerns regarding your own vehicle and how to perform modifications such as the one explained in the previous statements.