Fuses Overview

What Is a Fuse?

A fuse is a type of safety device used in circuits. They fit between the electrical sources and their loads, and if the current becomes too high the fuse will then activate, or “blow”. This disconnects the loads from the power source and it will reduce the risk of damage to the equipment and the possibility of a fire. When a fuse blows, they need to be thrown away and replaced, which makes them different from circuit breakers, which serve a similar purpose.

One of the biggest differences is that it is possible to reset circuit breakers. Fortunately, fuses have a very low cost and they are relatively easy to replace. When replacing a fuse, it is vital to replace it with a fuse of the same voltage rating and current carrying capacity. The safety measures they can provide make them eminently useful in many different applications.

 

How Does a Fuse Work?

The fuse is the “weak link” in the circuit, and that is just what it is supposed to be. They generally have a thin metal strip inside of them. This is the resistor component. The metal strip connects the circuit. When the current that runs through the circuit is too high, the metal heats up and actually melts. This action is what breaks the circuit. It causes a gap in the contacts. When this happens, the current stops flowing so there is no danger of overheating, and no danger of electrical issues that could result in a fire.

Different types of fuses have different current ratings that let the user know how much current is capable of passing through the fuse before it blows. The speed of the fuse refers to how fast it will melt when the current is too high. Fuses that blow quickly are generally a good option for sensitive types of devices that could receive damage easily when it comes to high temperatures.

When choosing fuses, buyers need to make sure they consider a variety of different factors to ensure they buy the proper fuses for their needs. They need to look at more than just the current rating, size, and speed of the fuse. They should learn how much energy the fuse releases when it blows, so they do not have a fuse that releases too much of that energy, which could be a danger to the equipment and people using it.

In the case of low voltage applications, knowing the voltage drop is a good idea as well. Voltage drop refers to the amount of voltage lost when it passes through a passive element, such as the fuse. With low voltage equipment, if the voltage drop is too great with the fuse, it could actually affect the device’s ability to function properly.

 

What Is a Fuse Used For?

The main purpose of the fuse is to ensure that the circuit does not overheat. Wires can only carry a certain amount of current before they begin to overheat. In some cases, the wires can become so hot that they melt the insulation that surrounds them, which could be quite dangerous. Fuses today are used for a variety of different applications and devices, including automobiles. In fact, they are one of the most common types of electrical components today.

A large part of their usage stems from the fact that they are safety items. Manufacturers, builders, and individuals all want to reduce their risk of injury, as well as liability. Fuses stop equipment and devices before they can become a danger. They are also very easy to replace, especially with a fuse puller. The cost for fuses is very low as well, so replacing a fuse is a minimal cost compared with the cost or time associated with a catastrophic loss from overheating equipment.

 

What Types of Fuses Exist?

Because they are useful in a number of different applications, a large number of different types of fuses are on the market today. Many industrial workplaces utilize high-voltage settings, as does the automotive industry. They make the fuses relatively easy to replace on purpose so the end-user can get things back in order with the equipment or vehicle very quickly. Once, fuses were common in houses as well. However, the creation of the circuit breaker rendered them obsolete.

 

What Are Automotive Fuses?

Automotive fuses help to keep all of the electrical wiring and components in automobiles safe. Several different types of automotive fuses are in use for different applications in the vehicle. The four classes of fuses for autos are blade fuses, glass tube (Bosch) fuses, fusible links, and fuse limiters. The fuses can be on fuse clips, inline fuse holders, or fuse blocks.

The blade type fuses, which are very easy to replace simply by pulling out the old fuse and pushing a new one into place, come in six different sizes, as well as a host of different ratings. The different sizes that fall under the blade category include maxi fuses, ATO fuses, Mini fuses, low profile mini fuses, micro2 fuses, and micro3 fuses.

Most vehicles will have two fuse boxes. They will have one under the hood and one that is under the dashboard. When a fuse blows, open the fuse box, find the appropriate fuse from the labels or the owner’s manual, and pull the fuse. It is usually possible to pull the fuse by hand, but tools are available to help in the event the fuse will not come out. Look at the fuse to see that it is indeed broken and then replace it with a fuse of the same exact type. Replacing automotive fuses is fast and simple, and can save on repair costs.

 

What Are Bolted Tag Fuses?

Bolted tag fuses are common for general industrial applications. The fuses are cylindrical and they have small brackets attached to both ends of the fuse. They receive their name because the user will actually bolt on these fuses using those brackets. These types of fuses are useful for a number of different applications, and the current rating and the size can actually vary greatly. They typically have low power loss and can often work well for high-density mounting applications.

 

What Are Bottle Fuses?

Bottle fuses, also called diazed fuses, are available in five different sizes. The tip diameter is the same as the diameter of the adapter screw holes. This ensures that there is never a danger of using the wrong type of fuse for the circuit. When a bottle fuse blows, the color indicator at the fuse head pops out. This lets users know that the fuse has indeed blown and that there is some other issue with the circuit.

 

What Are Cartridge Fuses?

These cylindrical fuses feature contact points at both ends, with the fuse link between the ends rated for 240 V circuits. Several different styles of cartridge fuse are available for different purposes. The ferrule fuses have a rating up to 60 amps, and the larger knife blade cartridge has a similar shape, albeit with blades on both ends. These fuses can protect circuits up to 600 amps.

 

What Are Tag Fuses?

Tag fuses are cylindrical fuses that have metallic tags that jut off each end of the fuse cap. They come in a variety of different styles, including the aforementioned bolted tags. These tags can extent from different areas of the fuse. Even though they perform the same task, the fact that the tags come off the fuse in different places or different styles means that they are useful in a variety of different applications. The various types of tag fuses include center blade tags, center bolt tags, and center slotted tags, offset blade tags, offset bolted tabs, and offset slotted tags.

 

What Are Centered Tag Fuses?

Centered tag fuses feature the cylindrical fuse with the metal tags coming off from the center of the fuse. Within this category of fuse are the center blade tag fuses, center bolted tag fuses, and center slotted tag fuses. They can be bolted, slotted, or solid tag fuses.

 

What Are Offset Tag Fuses?

With the centered tag fuses, the metal tabs extend from the center of the fuse. With this type of fuse, the tags actually jut out from the bottom of the fuse, or in some cases, one tag might extend from the top and the other from the bottom. It will depend on the exact fuse, as well as the application. As with the centered tag fuses, these tags will be solid, bolted, or slotted.

 

What Are Slotted Tag Fuses?

Slotted tag fuses, available as center tag fuses or offset tag fuses, look very similar to the bolted tag fuses on initial inspection. However, instead of having a hole in the center of the metal tag, these actually have a slot in the tag instead. As with the bolted and solid tag fuses, these come in a wide range of different sizes and ratings, so they are helpful for many different applications.

 

What Are Hole Mounted Tag Fuses?

These types of fuses have a decidedly different look from the other available fuses. They have a hole in the back of the square box that contains the fuse. The hole on the back features threads, which makes it easy for affixing to mounts. They are generally used for protecting semiconductors. As with other types of fuses, they have different ranges and sizes for various applications.

 

What Are Resettable Thermal Fuses?

Resettable thermal fuses are very useful when it comes to protecting products that are supposed to generate heat from overheating and receiving damage. These types of fuses function similarly to resistors, as they can actually adjust their resistance level depending on the temperature. They are “smarter” than the typical fuse. Normally the pellet inside of the fuse will stay solid, but if the temperature reaches a certain preset level, it will melt and cut off the circuit just as a regular fuse would do.

They do not break the circuit in the same way that a regular fuse would do though, since they are resettable. When the temperature drops, the wax pellet inside of the fuse solidifies and is ready to work again. These types of fuses are actually very accurate, which makes them popular.

They can trip faster at lower temperatures and less current as well, which helps to maintain a more consistent temperature.

 

What Are Non-Resettable Thermal Fuses?

Non-resettable thermal fuses are the traditional fuses used in heating applications. Where the resettable fuses are repeatedly usable, these fuses are only good for a single use. After they break the circuit, the user needs to replace them. Those fuses that do not reset and need replacements must be matched with the right type of replacement fuse for the voltage and current, the same as fuses used in other types of applications.

 

What Are Fuse Kits?

Fuse kits generally come with a range of different fuses useful for maintaining various types of equipment. Good kits have compartments for each of the different types of fuses, so the user always knows what they are pulling out and using. Some kits may also come with a fuse puller, but not all of them do. It is possible to find this tool, which helps make it easier to remove fuses, available separately. When choosing these kits, it is important to buy the ones that include the correct fuses with the proper ratings for whatever type of application or device they have.

 

What Are Neutral Links and Solid Links? What Is the Difference?

A neutral link is a metal connection that acts at the terminal position and is in use with a fuse holder, or several fuse holders. They will let the neutral connection without a fuse sit next to the live connections. The solid link is a solid piece of metal and works to convert fuse switches to circuit isolators, as well as shorting links and neutral links.