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Why Does My Inline Fuse Keep Blowing?

Are you finding that the inline fuse for your car amp keeps blowing, and you are not sure why? You’re certainly not alone.

In fact, this is a common problem among car audio fans, but what is causing it? Let’s find out. 

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There are several causes for the inline fuse to keep blowing or melting:

#1. Short on power wire between the battery and the amplifier.

#2. Pulling too much current through a fuse that is too small.

#3. Loose electrical connections. 

#4. Damaged fuse holder. 

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Tip: In some cases, the amplifier can cause an inline fuse to blow without other signs. If the amplifier is drawing more current than the fuse is rated to handle, it can cause the fuse to become overloaded and blow.

This can happen if the amplifier is underpowered for its driving load when it malfunctions or is pushed too hard.

In this article, I will detail the common causes behind fuse blowing and what you can do to fix it. 

Why Does My Amp Fuse Keep Blowing?

We all know how frustrating it can be when our amp fuses keep blowing. A few common causes could be the source of this issue.

#1. Short on Power Wire Between the Battery and the Amplifier.

When the power wire is too thin for the current or torn (it has a too large AWG number), it can contact the chassis or other metal parts and create a short circuit.

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This can damage the amp, but the amp blade fuses should blow first, or what is more common, the contact with the car body will cause a short and will cause the main fuse to blow right away.

#2. Drawing Too Much Current Through a Fuse That Is Too Small

This can happen when you use a smaller main fuse than required. For example, when the inline fuse is smaller than the blade amplifier fuse.

Let’s say you have two 40 amp blade fuses on your amp, and the inline fuse is 50 amp. In this case, the fuse would be overloaded and will blow.

The inline fuse should be the same as all combined blade fuses, never higher. It will still protect the system when it has a lower amperage, but it can blow every time the amplifier runs at its full power. 

The inline fuse is installed to protect the system, and if you have two 40 amp fuses like in the above example, the inline fuse should ideally be 80amp, but it can be higher if the wire can handle more current.

Remember, the inline fuse does not protect only the amplifier but the whole circuit, including the wires.

So, if the amplifier’s fuses are 80amp, and the power and ground wires can hold 150amp, you can use a 100amp inline fuse to protect the whole circuit. 

I recommend using ANL fuses and distribution blocks from InstallGear or Knukonceptz (links to Amazon). 

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#3. Loose Electrical Connections.

When electrical connection points are loose, there is also a high risk of a short.

If a connection of the power wire becomes loose, it can generate heat and cause issues with your fuses.

For example, if one of the screws holding a connection in place becomes loose, it can cause this place to heat up and potentially cause problems with your fuses.

Check all your connections, not just those to the amp but also between the battery, fuse holder, amp, and ground wire, and make sure they are securely connected.

Also, ensure the fuse holder sits stable without wobbling around and the fuse inside is tight.

#4. Damaged Fuse Holder.

In some cases, the fuse holder itself may be the cause of the problem. 

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If the contact points of the fuse holder are damaged or corroded, it can cause problems with the fusing. This can happen if you’ve used an old or worn-out holder for too long.

It is worth checking your fuse holder regularly to ensure it is in good condition and not causing problems like a loose fuse.

Steps to Troubleshoot the Issue

If you’re having issues with blown or melted fuses, there are a few steps you can take to try and troubleshoot the issue:

#1. Check the fuse size and ensure it is appropriate for the current being drawn.  

If the fuse is too small, you’ll need to replace it with a larger one better suited for the current being drawn.

#2. Inspect all wiring and electrical connections to make sure they are secure.

If you find any loose connections, tighten them up to see if that resolves the issue. You also need to replace wires with even slight signs of wear or tear.

#3. Check the fuse holder for signs of overheating or damage.

If the fuse holder is damaged or overheated, it may need to be replaced. 

When searching for a fuse holder, I do not recommend using those with spring-loaded clips holding fuses, as they tend to become loose over time. 


In summary, there are a few potential causes of blown or melted inline fuses, including drawing too much current through a fuse that is too small, loose electrical connections, and overheating the fuse holder.

If you’re having this issue, it’s important to identify and correct the root cause to ensure your car audio system is safe and functioning as it should.

By following the steps outlined above, you should be able to troubleshoot and resolve the issue.

If you’re unable to do so or do not have experience, seek assistance from a car audio specialist or car electrician.


What Could Be Causing My Inline Fuses to Blow or Melt?

Some possible causes of blown or melted inline fuses include:

#1. Drawing too much current through a too small fuse: If the fuse is not rated to handle the amount of current, it can become overloaded and blow or melt.

#2. Loose electrical connections: If a connection in your electrical system becomes loose, it can generate heat and potentially cause issues with your fuses.

#3. Overheating of the fuse holder: If the fuse holder is not rated to handle the amount of current your system is drawing, it can overheat and cause issues with the fuses.

How Can I Fix the Issue With Blown or Melted Inline Fuses?

To fix the issue with blown or melted inline fuses, you’ll need to identify and correct the root cause of the problem.

This may involve:

#1. replacing a fuse that is too small

#2 tightening loose connections

#3. replacing a damaged fuse holder

#4. replacing power wires.

What Are the Consequences of Not Fixing Blown or Melted Inline Fuses?

When the fuse blows, you must investigate this asap. Otherwise, you risk the possibility of further damage to your electrical system.

Should I Seek Professional Assistance to Fix the Issue With Blown Inline Fuse?

If you cannot identify and fix the issue with blown or melted inline fuses on your own, it may be necessary to seek assistance from a professional.

An experienced electrician or car audio technician can help you diagnose and resolve the issue.