Fuse Types

Ordinarily, fuses are components that offer protection to electrical devices against power surges and short circuits. However, a fuse used for the protection of a high-powered transformer cannot be employed for a small-circuit device, like a laptop.

Electrical fuses come in different shapes and sizes, work using different elements, and have different applications within their circuits.

In our guide, we present all the types of fuses used in electrical systems, differentiating them from the major categories into subcategories and more specific variations.

Let’s get right in.


Fuse Types

There are over 15 types of electrical fuses differentiated by working principles, construct, and applications. These include:

  1. DC Fuse
  2. AC Fuse
  3. Low Voltage Electrical Fuse
  4. High Voltage Electrical Fuse
  5. Cartridge Fuse
  6. D-Type Cartridge Fuse
  7. Link-Type Cartridge Fuse
  8. Rewireable Fuse
  9. Striker Fuse
  10. Switch Fuse
  11. Expulsion Fuse
  12. Drop-out Fuse
  13. Thermal Fuse
  14. Resettable Fuse
  15. Semiconductor Fuse
  16. Voltage Suppression Fuse
  17. Surface Mount Device Fuse
fuse types

All these will be individually explained in detail for your full understanding.

DC Fuse

Simply put, DC fuses are the type of electrical fuses used with direct current circuits. Although this is the main factor that differentiates them from Alternating Current (AC) fuses, there’s one more characteristic worth mentioning.

DC fuses are typically designed to be larger than AC fuses to avoid an extended electrical arc.

When there is excess current or a short circuit in a DC fuse and the metal strip melts, a gap is produced within the circuit.

However, due to the constant current and voltage supply in the circuit from the DC source, a small gap between both ends of the melted strip creates a possibility for constant arcing.

This defeats the purpose of the fuse as power still flows through the circuit. To prevent arcing, the DC fuse is made larger, which increases the distance between the two melted ends of the strip.

AC Fuse

AC fuses, on the other hand, are electrical fuses that work with alternating current circuits. They don’t need to be made larger thanks to the alternating frequency of the current supply.

Alternating current is supplied at a voltage that goes from a maximum level to a minimum (0V) level usually 50 to 60 times in a minute. This means that when the strip melts, the arc is easily extinguished when this voltage drops to zero.

The electrical fuse isn’t needed to be larger, as the alternating current stops supplying itself.

Now, AC fuses and DC fuses are the two main categories of electrical fuses. We then split these into two sub-categories; low-voltage electrical fuses and high-voltage electrical fuses.

Low Voltage Electrical Fuse

This type of electrical fuse works in a circuit with a voltage rating that is lower than or equal to 1,500V. These electrical fuses are commonly used in low-voltage electrical circuits and come in different shapes, constructs, and sizes.

They are also cheaper than their high-voltage counterparts and easily replaceable.

High Voltage Electrical Fuse

High voltage fuses are electrical fuses used with a voltage rating that is higher than 1,500V and goes all the way up to 115,000V.

They have applications in large power systems and circuits, come in different sizes, and employ more stringent measures to extinguish the electrical arc, especially when a direct current circuit is involved.

The high and low-voltage electrical fuses are then split into different types mainly defined by how they are constructed.

Cartridge Fuse

Cartridge fuses are the type of electrical fuses that have the strip and arc extinguishing elements completely enclosed in a ceramic or transparent glass body.

They are usually cylinder-shaped electrical fuses that have metal caps (called ferrules) or metal blades at both ends that serve as contact points to connect to the circuit. The fuse link or strip internally connects to these two ends of the cartridge fuse to complete the circuit.

You see cartridge fuses with applications in home appliance circuits like refrigerators, water pumps, and air conditioners, amongst others.

Although they are more present in low-voltage power systems of up to 600A and 600V ratings, you also see them used in high-voltage environments. Regardless of this and the addition of certain materials to limit arcing, their general construct remains the same.

Cartridge fuses may be split into two additional categories; D-type electrical fuses and Link-type fuses.

cartridge fuse

D Type Cartridge Fuse

D-Type fuses are the basic construction types of cartridge fuses that feature a base, adapter ring, cartridge, and fuse cap.

d type cartridge fuse

The fuse base is connected to the fuse cap and the metal strip or link is connected to this fuse base to complete the circuit. D-type fuses stop the power supply immediately when there is an excess current in the circuit.

Link Type/HRC Cartridge Fuse

link type fuse

Link-type or High-Rupturing Capacity (HRC) fuses implement two fuse links for a time delay mechanism when protecting against excess current or short circuits. This type of fuse is also called a High Breaking Capacity (HBC) fuse.

The two fuse links or strips are placed parallel to each other, with one coming with low resistance and the other coming with high resistance.

When an excess current in the circuit occurs, the low-resistant fuse link melts immediately but the high-resistant link holds the excess power for a short period. It then melts down if the power supply does not reduce to an acceptable level within this short period.

If the breaking current rating is, instead, hit immediately when there was an overcurrent in the circuit, the high-resistant fuse link will melt down instantly.

These HRC types of electrical fuse also use agents like quartz powder or non-conducting liquids to limit or extinguish the electrical arc. In this case, they are called liquid HRC fuses and are common in the high-voltage types.

car fuse

HRC electrical fuses come in other types, like bolted fuses having extending terminals with holes, and knife fuses which have common applications in automotive environments and feature blade terminals instead of caps.

Knife fuses typically come with plastic bodies and are easily removable from the circuit in case of a fault.

Rewireable Fuse

Rewireable fuses are also called semi-closed electrical fuses. They feature two parts made of porcelain; a fuse carrier with a handle and a fuse base which this fuse carrier plugs into.

Commonly used in residential and other low-current environments, the construct of rewireable fuses makes it easy to hold without risking electric shocks. The fuse carrier typically comes with blade terminals and has the fuse link in it.

When the fuse link melts down, the fuse carrier can be easily opened up to replace it. The entire carrier may also be easily replaced without any difficulty.

rewireable fuse

Striker Fuse

A striker fuse employs a mechanical system to act as protection against excess current or short circuits, and as an indication that the electrical fuse is blown.

This fuse works with either explosive charges or a loaded spring and a pin discharged when the link melts.

The pin and spring are placed in parallel with the fuse link. When the link melts, the discharge mechanism is triggered, causing the pin to shoot out.

striker fuse

Switch Fuse

Switch fuses are the type of electrical fuses that can be controlled externally using a switch handle.

switch fuse

With common applications in high-voltage environments, you control whether the fuses allow power to pass through or not by toggling the switch to the on or off position.

Expulsion Fuse

Expulsion fuses employ the use of boric gas to limit the electrical arcing process. They are used within high-voltage environments, most especially transformers of 10kV ratings.

When the fuse melts, the boric gas extinguishes the arc and is expelled through a tube opening.

expulsion fuse

Drop Out Fuse

Drop-out fuses are a type of expulsion fuse with the fuse link separated from the fuse body. These fuses have two main parts; the cutout body and the fuse holder.

The fuse holder has the fuse link in it and the cutout body is a porcelain frame that supports the fuse holder through contacts at the top and bottom.

The fuse holder is also held at an angle to the cutout body and this is done for a reason.

When the fuse link melts due to overcurrent or short circuits, the fuse holder disconnects from the cutout body at the top contact. This makes it drop due to gravity, hence the name “drop-out fuse.”

The dropping fuse holder is also a visual indication that the fuse is blown and needs to be replaced. This type of fuse is commonly used for the protection of low-voltage transformers.

drop out fuse

Thermal Fuse

A thermal fuse uses temperature signals and elements for protection against overcurrent or a short circuit. Also known as thermal cutouts and having common applications within temperature-sensitive appliances, this type of fuse employs a sensitive alloy as the fuse link.

When the temperature hits an abnormal level, the fuse link melts and cuts off power to other parts of the appliance. This is most especially done to prevent a fire outbreak.

thermal fuse

Resettable Fuse

Resettable fuses are also called polymeric positive temperature coefficient (PPTC) fuses or “polyfuses” for short and have features that make them reusable. 

This type of fuse consists of a nonconductive crystalline polymer mixed with conductive carbon particles. They work with temperature for protection against excess current or short circuits. 

When cold, the fuse remains in a crystalline state that keeps the carbon particles close to each other and allows power to pass through it.

In the case of an excess supply of current, the fuse heats up, changing from its crystalline form to a less compact amorphous state.

Now, the carbon particles are farther apart, limiting the flow of electricity. Power still flows through this polyfuse when activated but it typically measures in the milliampere range. 

When the circuit cools down, the compact crystalline state of the fuse is restored and power flows through unhindered.

From this, you see that Polyfuses automatically reset, hence the name “resettable fuses.”

They are commonly found in power supply boards of computers and phones as well as in nuclear systems, air travel systems, and other systems where the replacement of parts will prove extremely difficult.

resettable fuse

Semiconductor Fuse

Semiconductor fuses are ultra-fast-responding fuses. You use these for the protection of semiconductor components within a circuit, such as diodes and thyristors, as they are sensitive to small current spikes. 

They are commonly used in UPSs, solid-state relays, and motor drives, among other devices and circuits with sensitive semiconductor components.

semiconductor fuse

Overvoltage Suppression Fuse

Overvoltage suppression fuses use temperature signals and temperature-sensitive elements for protection against voltage spikes. A good example of this is the negative temperature coefficient (NTC) fuse.

NTC fuses are placed in series within the circuit and reduce their resistance when there is a higher temperature.

This is the direct opposite of PPTC fuses. During a power spike, the reduced resistance causes the fuse to absorb more power, which reduces or “suppresses” the power that flows through.

overvoltage suppression fuse

Surface Mount Device Fuse

Surface Mount Device (SMD) fuses are extremely small types of electrical fuses commonly used in low-current environments where space is limited. You see their applications in DC devices like mobile phones, hard drives, and cameras, among others.

SMD fuses are also called chip fuses and you may also find high-current variants of them.

Now, all the types of fuses mentioned above have several additional characteristics that define how they behave. These include the current rating, voltage rating, fuse response time, breaking capacity, and I2T value.

surface mount device fuse

Video Guide

How The Fuse Current Rating Size Is Calculated

The current rating of fuses used in standard operating devices is typically set to between 110% to 200% of their circuit rating.

For example, the current rating of fuses used in motors is typically set to 125%, while the current rating of fuses used in transformers is set to 200%, and the current rating of fuses used in lighting circuit systems is set to 150%. 

These, however, depend on other factors like the circuit environment, temperature, sensitivity of protected devices in the circuit, and a whole lot of others. 

When calculating the fuse rating size for a motor, for example, you then use the formula;

Fuse rating = { Power (w) / Voltage (v) } x 1.5

If the power is 200W and the voltage is 10V, the fuse rating = (200/10) x 1.5 = 30A. 

Understanding Electrical Arcing

Reading to this point, you would’ve come across the term “electrical arcing” multiple times and seen that there is a need to prevent it when the fuse link melts. 

An arc is produced when electricity bridges a small gap between two electrodes through ionized gasses in the air. The arc is not extinguished unless the power supply is stopped. 

If the arc is not controlled through the applications of distance, non-conductive powder, and/or liquid materials, you risk a continuous supply of overcurrent in the circuit or a fire outbreak.

If you want to learn more about fuses check this page.


How Many Types of AC Fuses Are There?

There are two major categories of AC fuses, low and high-voltage fuses.
Which may then be split into up to 11 or more different types.

How Many Types of Fuse Do We Have in Electrical?

There are over 11 types of fuses used in electrical systems and these are split into the main AC and DC fuse categories. Fuses are also differentiated by the high and low voltage sub-categories.

Alex Klein Author


Alex Klein is an electrical engineer with more than 15 years of expertise. He is the host of the Electro University YouTube channel, which has thousands of subscribers.