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Making Sense of Auto Fuses

Posted by Kimball Midwest on July 30, 2018

Tags: Electrical, Automotive, Fuse

Despite its small size, an auto fuse is a critical component in your vehicle, protecting the valuable and delicate electronics in the event of a sudden electrical surge. Fuses are designed to melt if exposed to an overcurrent—interrupting the circuit before it causes more significant damage—but they are generally easy and inexpensive to replace.

A fuse is composed of a housing, fuse element and contacts, and they vary in size and configuration. They come in either blade or cartridge-style.

Fuse Infographic

Blade Fuses

ATO fuses and ATC fuses are regular-sized automotive blade fuses. They are interchangeable, provided the amperage rating is the same, with one major difference. The O in ATO refers to the open housing space between the blades that exposes the fusible element. The C in ATC stands for closed housing, which protects the fusible element from moisture and other factors that can cause corrosion or damage.
ATO/ATC Fuse Facts:
  • Available in amperage ratings of 1A to 40A
  • Transparent housing for easy identification of blown fuse
  • Used in automotive, watercraft and low-voltage applications (maximum 30 volts)
Mini fuses look like ATO and ATC fuses but are much smaller in size. This allows you to use more fuses in the same amount of space. For newer vehicles, these fuses protect the additional circuits and onboard electronics without adding bulk.
Mini Fuse Facts:
  • Available in amperage ratings of 2A to 30A
  • Transparent housing for easy identification of blown fuse
  • Silver-plated terminals for superior conductivity
Maxi fuses are larger than ATO/ATC fuses and offer protection for high amperage vehicle circuits. They are a blade-type fuse designed to replace fusible links or fusible wire. The fuse link is completely enclosed to help protect against moisture and other corrosive or damaging elements.
Maxi Fuse Facts:
  • Available in amperage ratings up to 80A
  • Transparent housing for easy identification of blown fuse
  • Interrupting rating: 1000A @ 58 DC
Blade fuses are color-coded according to amperage rating:

Amperage Rating Color
1A Black
2A Gray
3A Violet
4A Pink
5A Tan
7.5A Brown
10A Red
15A Blue
20A Yellow
25A Clear (Gray for Maxi fuses)
30A Green
35A Blue-Green (Brown for Maxi fuses)
40A Orange
50A Red
60A Blue
70A Amber/Tan
80A Clear
100A Violet
120A Purple
Fuse Infographic2

Cartridge-Style Fuses

A JCase fuse is a cartridge-style fuse in a recessed female terminal. The JCase Low Profile fuse has a lower profile and shorter male blade terminals but performs the same as a standard JCase.
JCase Fuse Facts:
  • Available in the following amperage ratings: 20A, 25A, 30A, 40A, 50A and 60A
  • Rated at 58 volts DC
  • Interrupting rating: 1000A @ 58 DC
  • Operating temperature range: -40°F to 257°F
  • Features low voltage drop and increased time delay to protect high inrush currents
  • Used for automotive and watercraft
PAL Auto Link fuses are rectangular cartridge fuses common in many Japanese and domestic vehicles. They are designed to withstand higher temperatures for longer periods of time and are made for higher amperage circuits, such as alternators and starters. The cartridges can be male or female; the male terminal fuses have either bent or straight contacts that can be bolted down.
PAL Auto Link Fuse Facts:
  • Available in amperage ratings from 20A, 30A, 40A, 50A, 60A, 70A, 80A, 100A, 120A
  • Transparent top for quick identification of blown fuses
  • Rated at 32 volts DC
FMM Fuses are small female Maxi cartridge fuses that save space in vehicle fuse boxes. They offer protection for high current circuits.
FMM Fuse Facts:
  • Available in the following amperage ratings: 15A, 20A, 25A, 30A, 40A
  • Rated at 32 volts DC
Cartridge-style fuses come in the following colors to indicate their amperage rating:

        Amperage Rating       Color
15A Grey
20A Blue
25A White
30A Pink
40A Green
50A Red
60A Yellow
70A Yellow
80A Black
100A Blue
120A Grey
Fuse Infographic3

Blo-N-Glo Fuses

Another option is the Blo-N-Glo fuse, which features a built-in light that glows when the fuse is blown, saving you the time of removing and checking every fuse to find the problem.
Blo-N-Glo Fuse Facts:
  • Available in ATO, ATM, Maxi and JCase styles
  • Used for automotive and low-voltage applications (maximum 30 volts)
To ensure your shop always has the fuses you need, Find A Rep
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