How To Test A Ceramic Fuse?

Ceramic fuses are responsible for saving electronic devices from many issues, such as power overload or surge occurrences. And it is not unusual for the fuse to blow. If the thin filament inside melts, the fuse will no longer protect the appliance. But do you know how to test a ceramic fuse to check if it is blown?

There are two ways to test a ceramic fuse: with and without a multimeter. You need to touch the ends of the fuse with the multimeter probes. If the meter reads higher than zero, the fuse is blown. On the other hand, you can test a ceramic fuse without a multimeter by inspecting it in various ways.

How To Test A Ceramic Fuse

It is easy to test a glass fuse as everything inside is visible. But identifying a faulty ceramic fuse is pretty challenging.

That’s why it becomes essential to learn everything about testing and replacing ceramic fuses. Today I will share all the necessary information based on my experience, and I believe you will find this article helpful.

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What Is A Ceramic Fuse?

Before we talk more about ceramic fuses, let’s get to know ceramic fuses first. Because if you do not know the anatomy of such a fuse, it will be challenging to identify a faulty fuse or replace one.

So, what is a ceramic fuse?

A ceramic fuse is a small device with screws and wires in it. To be more specific, a ceramic fuse has two screws and a wire that passes through them. Almost all house switchboards have a fuse in them. It can even be in electronic appliances, such as a microwave.

The wire inside the fuse is not very long-lasting. However, they are durable enough to protect various electronic items.

The load of the circuit a fuse can take determines its rate. If it receives more load than it can take, the fuse gets blown or burnt out. Ceramic fuses are small in size, and you will need a torch to find it and during replacement.

What Is A Ceramic Fuse Used For?

Do you know why the ceramic fuses exist or what they are used for? Well, you have noticed in the previous section I mentioned that a ceramic fuse takes circuit load. That is where its potential lies.

A ceramic fuse is used for protecting various appliances from getting damaged, including consumers’ electronics. When you plug in an electronic appliance, it will have to go through a high power wave. If the power is too much, it will immediately damage the appliance.

And that is where the ceramic fuse steps in. It protects the appliances from the high power current by minimizing the flow. So basically, this device works as an interrupter during power overload.

This capacity of ceramic fuses is their biggest advantage. And that is why ceramic fuses are an essential part when it comes to protecting electronic items.

How To Test A Ceramic Fuse?

You never know when the circuit receives too much power. It results in melting the fuse wire. And once it happens, the fuse will no longer interrupt power to protect the electronic appliances. That is why you need to test the ceramic fuse to know if it is working correctly or if you think the fuse is blown.

You need a multimeter to test a ceramic fuse. It will make the job easier. You can follow these steps to know if your ceramic fuse is working or not.

Step 1: Turn Off The Appliance

The first thing to do is to turn off the appliance. You cannot test a fuse while it is on. If you do, it can cause various misshapes. Moreover, it will keep your electronic appliance from any kind of distortion. If the appliance is plugged in, unplug it as well.

Step 2: Remove The Fuse

Your next job would be removing the fuse from the appliance. It is not a very tough thing to do. You only need to pull it out of the slot. Make sure to pull it out gently so that it will not damage any other parts.

Step 3: Set Up The Multimeter

You will need a multimeter to check the continuity of the circuit or ohms. It will help determine whether the fuse is working or not. But before you do that, you must know how a multimeter works.

A multimeter has two probes to measure positive and negative energy. The multimeter runs on a battery, whose job is to spread current through the circuit. This will help you understand how much energy is passing through the circuit.

You can either check by measuring the circuit continuity or the resistance in ohms, which has the omega symbol in the system. If you are checking for resistance, turn the multimeter dial to zero. You can set the meter’s probes or leads side by side to hear a clicking sound to know if the meter is working.

Step 4: Check The Fuse

This step also does not need an expert. You can easily check the fuse. It has two ends, and there is no need to stress over trying to find out which one is negative and which one is positive. It will not affect anything when you test the fuse with the multimeter.

Step 5: Test The Fuse

The final step is to test the fuse. Now, the multimeter reading system will be different based on whether it is an analog or digital meter. If it is an analog multimeter, place the black probe of the meter at one end of the fuse, and place the red probe on the other end.

Then wait for hearing a beeping noise coming from the meter. If you don’t hear any sound, the fuse must be blown.

If you are using a digital multimeter, the display reading will help you understand if the fuse is working. If you are testing by reading resistance, put the setting to omega. Then touch the multimeter probes together, and you will notice that the meter reads zero.

Now place the probes at the ends of the fuse. If the fuse also reads zero, the fuse is working. But if the meter shows more than zero, the ceramic fuse is blown.

How To Tell If A Ceramic Fuse Is Blown?

It is easy to see through a glass fuse as it is transparent. You can clearly see the screw ends and the wire. On the contrary, ceramic fuses are the most challenging to identify. The surface of the fuse is usually covered by white ceramic, making it impossible to tell what is going on inside.

Then how can you tell if the ceramic is blown or not? The most common method of telling if ceramic is blown is to check the circuit continuity by using a multimeter. Placing the multimeter probes or leads at both ends of the fuse will help you know if the ceramic is blown.

You can tell if the ceramic is no longer working if the ohms read more than zero. If the meter has a needle, it will read more than zero, meaning the fuse is blown.

You can also tell if a ceramic fuse is blown without a multimeter. But in that case, you need to be visually attentive. A blown ceramic can appear burnt. The white of the ceramic will look dark around the middle as the wire tends to melt or blow around that part.

Another way of telling if the ceramic is blown is by exchanging it with a new or good fuse to see if they show different results. This method is quite hectic, and I think using a multimeter is easier than doing this.

How To Tell If A Ceramic Fuse Is Blown Without A Multimeter?

Testing a ceramic fuse with a multimeter and telling if it is blown looks simple, right? The meter gives an accurate reading, making it more reliable to identify a damaged ceramic fuse.

But without a multimeter, doing the same job involves different techniques. Nevertheless, you can test if a ceramic fuse is blown or malfunctioning using a few methods.


If you are inspecting a ceramic fuse when it is still the socket, take a torchlight to inspect it. You may not spot the issue immediately, but you need to pay attention.

Look for the blackened mark on the fuse. The ceramic fuse is white, and this part should not be difficult. Sometimes, the surface cracks when the ceramic blows. So if you find any visible crack, the fuse is probably faulty.


If you are checking the fuse of equipment or appliances that have more than one fuse, you can try the swapping method. Take out the fuse from the working part and replace it with the fuse of the malfunctioning part. If the part of the appliance works with a different fuse, it means the previous fuse was faulty or blown.

What Does A Blown Ceramic Fuse Look Like?

At first glance, the ceramic fuse may look good. But that often happens in the case of other types of fuses as well. However, it is possible to tell if the ceramic is blown by inspecting it.

The fuse will look blackened on the outside if the wire is blown inside. Sometimes, the ceramic surface also cracks, which is another way to tell that the ceramic is blown.

Where Is The Ceramic Fuse On A Microwave?

Yes, microwaves also have ceramic fuses. That’s what protects the microwave from heavy power flow and getting damaged. But where do you think this little fuse is located?

There is a cabinet next to the entry point of the power cord of the microwave. The ceramic fuse is located in that cabinet. It operates from there to prevent the microwave from malfunctioning in case any issue happens.

How Do You Replace A Ceramic Fuse In A Microwave?

If you think or find out that the ceramic fuse of your microwave is faulty, it is best to replace the fuse with a new one. Here is how you can replace the microwave ceramic fuse.

  • As usual, the first thing you need to do is to unplug the microwave from the power socket.
  • Then you need to remove the ceramic fuse from its socket. But to do that, you may or may not have to remove the microwave from installation, and it will depend on the type of microwave system.
  • If you cannot access the control panel where the microwave is located, you need to remove the microwave from installation.
  • Once you reach the ceramic fuse, carefully remove the wires and other components from around it.
  • Now remove the old fuse and set the new one in its place.
  • Put back all the wires and components as they were with the previous fuse.
  • Once you are done putting everything together, plug in the microwave and see if it is working again.

List Of Ceramic Fuse For Microwave

Are you looking for a ceramic fuse for your microwave? You can check out the following fuses I have picked.

BlueCatELE 20 Amp 250V Ceramic Fuse For Microwave Ovens

The BlueCatELE 20 Amp 250V ceramic fuse set is made to fit various microwaves, including Whirlpool and Kenmore. The universal size of the fuses ensures you don’t worry about whether or not the fuse will fit your microwave.

This ceramic fuse set contains both nickel and metal. The package contains five such ceramic fuses, giving you plenty to store for the future.

The 20 Amp 250 Volt power capacity ensures protection of the microwave against power issues like circuits. Moreover, the fuses will prevent other issues, such as overheating. So this cost-effective fuse set can save your expensive microwave.

RadioShack 15 A 250V Ceramic Fuse For Microwave Ovens

This ceramic fuse pack from RadioShack has less amperage rating than the previous one. But it is effective in case your microwave needs a fuse with lower amperage.

You get four ceramic fuses here to replace your damaged microwave fuse and keep the extras for the future. Though the fuse has a 15 Amp capacity, it can tolerate up to 250-volt power to ensure protection for your microwave.

Each fuse measures 1 1/4 × 1/4 in size and comes in one size only. If you are worried about whether it will fit your microwave, make sure you know the exact size of your microwave fuse.

Can I Replace A Ceramic Fuse With A Glass One?

You can surely replace a ceramic fuse with a glass one. However, it is not recommended unless the voltage and amperage ratings are the same. Ceramic fuses tend to have more power current capacity than glass fuses.

So even if both types of fuses appear to have similar power, the outcome can be different sometimes. But let’s go through ceramic fuse vs. glass fuse to learn a bit more about them. It will help you understand which type of fuse you should go with.

Ceramic Fuse

Ceramic fuses are more common in households and various electronic appliances. This type of fuse has high heat tolerance. As a result, it protects the equipment or appliances from overheating issues.

Moreover, ceramic fuses are more powerful when it comes to interrupting power surges. Unfortunately, this fuse has drawbacks, such as being very fragile. And, unlike glass fuses, this fuse is not transparent, making it difficult to tell if the fuse is blown.

Glass Fuse

Glass fuses have been available longer than ceramic fuses. The biggest advantage of this fuse is that it is transparent. You can see the filament inside without much inspection. Thus, this fuse makes it easier to tell if the fuse is blown.

But the biggest drawback of a glass fuse is that it does not have a high amp capacity. The wire will melt easily if the fuse goes through a high voltage.

Frequently Asked Questions

Q. Are Ceramic Fuses Color Coded?

Yes, most ceramic fuses are color-coded because it indicates the amperage rating of the fuse. All ceramic fuses are made of ceramic insulators. They also contain a metal color stripe at one side. That’s how people know how much amperage it will be compatible with.

Q. Are Ceramic Fuses Illegal?

Ceramic fuses are no longer used in home appliances in the USA and many other countries. The color-coding system upgrades every three years, making it difficult to maintain the use of such fuses. So, if your home has such fuses, it is best to upgrade them as soon as possible.


There is no denying that ceramic fuses are great and more reliable when it comes to protecting household items. But knowing how to test a ceramic fuse comes in handy, especially if the appliance is malfunctioning frequently.

The easiest way to find out if the ceramic is good is to use a multimeter. But if you do not have a multimeter, you can try other methods to find out. And whatever you do, don’t forget to turn off or unplug the item before you check on it or replace the fuse.

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