Automotive fuses are a class of fuses used to protect the wiring and electrical equipment for vehicles. They are generally rated for circuits no higher than 32 volts direct current, but some types are rated for 42-volt electrical systems. They are occasionally used in non-automotive electrical products. Automotive fuses are typically housed inside one or more fuse boxes (also called an integrated power module (IPM)) within the vehicle, typically on one side of the engine compartment and/or under the dash near the steering wheel. Some fuses or circuit breakers may nonetheless be placed elsewhere, such as near the cabin fan or air bag controller. They also exist as circuit breakers that are resettable using a switch.
There may be a fuse for ignition off draw (IOD), which controls the drawing of electric current in a vehicle while it is shut off; removing this fuse while the vehicle is shut off for more than a few weeks will prevent excessive depletion of the battery.
Blade type
Blade fuses (also called spade or plug-in fuses), with a plastic body and two prongs that fit into sockets, are mostly used in automobiles. Other common usage is in equipment with comparatively simple, low voltage DC electrical systems such as towed campers and marine applications such as sailboats and motor boats (typically smaller cabin cruisers).
Each fuse is printed with the rated current in amperes on the top.
These types of fuses come in six different physical dimensions: Micro2. Micro3. LP-mini (APS), also known as low-profile mini. Unofficially, the "low-profile mini" fuse is sometimes incorrectly called "Micro" since the term means smaller than mini, but recently fuses using the Micro name have been released. Mini (APM / ATM). The mini fuses were developed in the 1990s. Regular (APR / ATC / ATO / ATS) blade-type fuses, also known as standard, were developed in 1976 as ATO by Littelfuse for low voltage use in motor vehicles. Bussmann makes the ATC that also complies with the same ISO 8820-3 and SAE J1284 standards. OptiFuse, a newer entrant in the market, makes regular (APR / ATC / ATO) fuses that meet the same standards. Maxi (APX), heavy-duty.
Mount
Blade type fuses can be mounted in: Fuse blocks (made of porcelain, slate, or other refractory material). Fuse blocks offer a method of mounting several fuses together or large fuses separately. In-line fuse holders, with two standards: IEC publication 257 1968 Amendment no. 2 to this publication dated January 1989 and UL-standard no. 512. They help to save space. An inline fuse is often seen in add-on electrical accessories, where the manufacturer does not know the electrical current limit of the circuit you are going to patch into. This offers sufficient protection for that individual accessory, without regard to any other devices that might share the same circuit. Dual slot fuse holders let you turn one fuse slot into two (in some way, similar to a power strip, but for fuses). Fuse clips. Fuse clips can be inserted into a printed circuit board.
Size groups
Where space permits, a miniature circuit breaker is sometimes used to replace a blade-type fuse in the same fuse holder.
Blade fuses use a common coloring scheme for the Micro2, Micro3, low-profile (LP) Mini, Mini, and regular size fuses, and a partial color similarity with the maxi size fuses. The following table shows the commonly available fuses for each size group.
Regular fuses (ATO) rated 0.5 A, 35 A and 40 A are not mentioned in the DIN standards, but are available in some products from Littelfuse, among others.
Cartridge type
Several cartridge type fuses are used in automotive applications, including MCASE, MCASE+, JCASE, and low-profile JCASE types.
Bosch type
Bosch type fuses (also known as ceramic, porcelain, continental, torpedo, European, or GBC type fuses) are used in old (often European) automobiles. The physical dimension of this type of fuse is 6×25 mm with conical ends. Bosch type fuses usually use the same color-coding for the rated current. The DIN standard is 72581/1.