OptiFuse announces the release of our 2024 Automotive Aftermarket Circuit Protection Catalog

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Get expert advice on fuses, circuit breakers, and electrical safety trends with the OptiFuse blog. Stay informed on the latest in circuit protection and components.

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Choosing the right circuit protection devices for your applications is crucial for protecting your employees, your equipment, and of course yourself. Of the devices available to choose from, there are two predominant categories: fuses and circuit breakers. Both devices serve the same purpose, to protect electrical circuits against damaging and dangerous overcurrents. But they do so in different ways. Fuses have a filament inside that melts when overheated, cutting off the current flow. Circuit breakers, meanwhile, have switch mechanisms that trip at the onset of unsafe surges of electricity. More technically, they have a bi-metal strip that bends and opens the circuit, cutting off current flow. This bi-metal strip can unbend and resituate itself back on the contact post, re-connecting the circuit. This unbending capability is what provides resettability to circuit breakers. Those and other key differences between fuses and circuit breakers should be considered before deciding which device best meets your needs.

Designed to allow electric currents to safely flow during normal operation but will quickly open when an overcurrent develops. Their defining characteristics include their physical size, interrupting ratings, construction, opening speed, electrical ratings and safety agency approvals.
<a href="https://www.optifuse.com/fuses/" target="_blank" rel="noopener">Fuses</a> generally react quicker to overcurrents than circuit breakers and are usually cheaper, but they must be replaced after they have been used to deter one overcurrent. There are resettable fuses (PTCs) available for certain applications, but unlike circuit breakers, most fuses must be replaced after a single use.
In general, fuses are more widely available than circuit breakers and they offer a smaller footprint.

Fuses

Circuit Breakers differ from fuses because they can be repeatedly tripped and reset in the event of overcurrents. They do not need to be replaced after each use like most fuses do.
Circuit Breakers, come in one of three different reset types. Depending on which type you choose, the breaker will either reset itself automatically or will require you to manually reset it to restart the flow of electricity following an overcurrent event.

Circuit Breakers

Compared to fuses, <a href="https://www.optifuse.com/circuit-breakers/" target="_blank" rel="noopener">circuit breakers</a> are typically more expensive but are also more robust and can protect against higher currents and amperages. That is especially true of our heavy duty high amperage circuit breakers. They are built to handle the heavy duty loads associated with many vehicles. Some of our circuit breakers also come with external status indication that helps users determine when the device is tripped and, in the case of Type III breakers, when it needs to be reset.

Key Differences

Circuit Protection Types: Fuses vs. Circuit Breakers

Choose the right circuit protection for your needs. Learn the key differences between fuses and circuit breakers, including how each protects against overcurrents.

Circuit Protection Types: Fuses vs. Circuit Breakers | OptiFuse

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Oihane Fernandez de Retana

Automotive low voltage circuit breakers are available in three different reset types, as designated by SAE in its J553 specification. Each type performs the same basic function, which is to clear a circuit in the event of an overcurrent, usually by utilizing the heat from an overcurrent to trigger a heat-sensitive mechanism that cuts off current flow. The reset types available for automotive circuit breakers are type I (automatic reset), type II (modified reset) and type III (manual reset).

Before deciding which type of <a href="https://www.optifuse.com/circuit-breakers/" target="_blank" rel="noopener">circuit breaker</a> is right for you, consider factors relating to the application in which you plan to use the breaker.

How to Choose a Reset Type

Circuit Breakers Reset Types

Automotive low voltage circuit breakers come in three reset types—automatic, modified, and manual—each designed to clear circuits during overcurrent events.

Circuit Breakers Reset Types | OptiFuse

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In-line fuse holders are designed to make mounting fuses painless and easy in a variety of applications. Often used as a part of a wire harness assembly, they are ideal for applications in which no surface is available to secure another type of fuse mount. They are commonly utilized to protect individual electrical accessories in applications such as trucks, vans, boats, construction equipment, utility vehicles and RVs. With a build designed to withstand harsh environments, they are also used in off-road vehicles and other applications that experience rough conditions. Every application is different and virtually every installation requires a certain amount of additional work to properly install the fuse and/or fuse holder. A custom fuse holder eases the installation and provides a cost-effective solution as compared with the added installation costs. At OptiFuse, we offer several customization options for <a href="https://www.optifuse.com/fuse-holders-blocks-and-accessories/automotive-blade-fuses-4/in-line-fuse-holder-5/">in-line fuse holders</a>, letting you build the exact product that you want and need. Choose the body style and color. Different wire types and terminations are available, and we offer multiple wire colors, gauges and lengths. Additionally, a preinstalled fuse can be delivered with the fuse holder.

In-Line Fuse Holder Customization Guide

OptiFuse’s in-line fuse holders offer easy mounting and customization. Choose body style, color, wire types, terminations, and more for a tailored solution.

In-Line Fuse Holder Customization Guide | OptiFuse

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Versatile, simple to use and easy to inventory. With only two part numbers, OptiFuse’s new modular design allows for the creation of four different Regular (ATO/ATC style) blade fuse blocks.

<img decoding="async" class="details-image" draggable="false" src="http://cms.optifuse.com/uploads/2024/09/modular-fuse-blocks.png" alt="Two OptiFuse Modular Components Individually: Key Parts for Creating Blade Fuse Blocks" />
• Accepts regular (ATO/ATC style) blade fuses.
• Rated up to 30A per position and 100A total for the block.
• Built with an LED light for each circuit that illuminates when a circuit opens and a fuse needs to be replaced.
• Comes with an insulating cover that offers protection against short circuits, as well as from dirt, dust, and splashes.
• Designed with screw terminals for secure wiring, especially beneficial in emergency vehicles.
• Fuse block comes with 60 pieces assorted label stickers and storage for 2 spare fuses.

Basic Modules: 2 MODULES for 4 BLOCKS

Basic Modules

Combined Models

*All models can also be sold without covers or without blown fuse indicating LEDs.

Modular Design Fuse Blocks: 4 Blocks with only 2 Modules

OptiFuse’s modular design offers versatility and simplicity. With just two part numbers, create four different ATO/ATC style blade fuse blocks easily.

Modular Design Fuse Blocks: 4 Blocks with only 2 Modules | OptiFuse

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Tube fuses have long been a standard circuit protection device. Built out of different materials and coming in different sizes, they are dynamic circuit protectors with many uses across multiple industries. Same as for the other fuses, in order to select the proper tube fuse three electrical ratings need to be considered: nominal current, voltage, and interrupting rating. Additionally, in applications in which the fuse must sustain large current pulses of a short duration, the nominal melting I2t should be analyzed too. Besides these general considerations, there are other parameters specific for tube fuses that are involved with the fuse selection. They come in various sizes, glass or ceramic constructions, distinct response time, and are built for use for use in a myriad of industries. Below, we provide help for how to choose the best tube fuse for your applications.

AG Fuses
 
The “AG system” of sizing fuses, (where “AG” stands for “Automotive Glass”) vary in length, diameter and amperage rating. Below you will find a table of dimensions cross referencing the common AG size to the corresponding dimensions:

SFE Fuses
 
Engineered to specifications set by the Society of Fuse Engineers, the “SFE system” sized fuses are always 1/4&#8243; in diameter, but their length depends on the current rating, ranging from 5/8&#8243; for a 4A, to 1-7/16&#8243; for a 30A, to ensure accurate fuse replacement.

How to Choose a Tube Fuse

Discover glass and ceramic tube fuses, a versatile circuit protection solution. Learn how to choose the right size, material, and response time for various industrial applications.

How to Choose a Tube Fuse | OptiFuse

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Although care is taken to properly design electrical and electronic circuits; overcurrents in the form short circuits and overload can occur. The sole purpose of fuses and circuit breakers is to protect personnel and/or equipment from serious harm when an overcurrent condition arises. This guide is intended to help create a better understanding the various parameters of overcurrent protection and the proper application circuit protective devices. This guide creates a basic understanding of overcurrent principles and applications but is not intended to supplant sound engineering principles or replace speciﬁc application testing.

1. Understanding Overcurrents
2. What is the normal operating current of the circuit?
3. What is the operating voltage?
4. Is the circuit AC or DC?
5. What is the operating ambient temperature?
6. What is the available short circuit current?
7. What is the maximum allowable I²t?
8. Are there in-rush currents available?
9. Is the protective device being used for short circuit protection, over-load protection, or both?
10. What are the physical size limitations?
11. Is the PCB surface mount or thru-hole?
12. Does the fuse need to be &#8220;ﬁeld-replaceable&#8221;?
13. Is resettability an issue?
14. What safety agency approvals are needed?
15. How will I mount the device?
16. What are the cost considerations?

In order to select the proper protective device, the following parameters and criteria need to be considered: 

Fuse Selection Guide

Learn how to select the right fuses and circuit breakers for overcurrent protection. Our guide covers essential parameters and application tips for effective safety.

Fuse Selection Guide | OptiFuse

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