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 24 volts direct current, but some types are rated for 42-volt electrical systems. They are occasionally used in non-automotive electrical products.

Plug-in fuses (also called blade or spade fuses), with a plastic body and two prongs that fit into sockets, are mostly used in automobiles. These types of fuses come in four different physical dimensions: mini (or minifuse or ATM), low-profile mini, ATO (or ATC) and maxi (or maxifuse). ATO fuses were developed in 1976 for low-voltages use in motor vehicles. A common label name is ATO - Fuse, (A utomotive Technology Organization). Their sizes and designation:

It is possible to replace an ATO-type plug-in fuse with a circuit breaker that has been designed to fit in the socket of an ATO-sized fuse holder. These circuit protectors are more expensive than a regular fuse.

Blade fuses use a color-coding standard. The Mini (ATM) and ATO style fuses use the same color-coding system, while the larger maxi fuses use a different system, with only some colors representing the same current ratings.

Mini, Low-Profile Mini, and ATO Color-coding:

* = available in ATO fuses only

Maxi Color-coding:

Bosch type

Bosch type fuse (used in older cars)

Bosch type fuses (also known as torpedo type fuses) are used in old (often European) automobiles. The physical dimension of this type of fuse is 6x25 mm with conical ends. Bosch type fuses usually use the same color coding for the rated current. The DIN standard is 72581/1. The size of the fuse is: 6x25 mm.

Lucas type

Lucas type fuses are used in old British-made or assembled automobiles. The physical length of this type of fuse is either 1" or 1.25", with conical ends. Lucas type fuses usually use the same color coding for the rated current. Lucas fuses have three ratings; the continuous current they are designed to carry, the instantaneous current at which they will fuse, and the continuous current at which they will also fuse. The figure found on Lucas fuses is the continuous fusing current which is twice the continuous ampere rating that the system should be using; this can be a source of confusion when replacing Lucas fuses with non Lucas fuses.

SAE fuses

North-American built automobiles up to 1981 had electrical systems protected by glass cartridge fuses rated 32 volts and current ratings from 4 amperes to 30 amperes. The fuse dimensions and characteristics are standardized by the Society of Automotive Engineers standard J554. All fuses are 1/4 inch diameter, and the length varies according to the rating of the fuse. A 4 Amp fuse is 5/8 of an inch long, a 20 Amp fuse is 1 1/4 inches long, and a 30 amp fuse is 1 7/16 inches long. ^[5]

Strip fuses

Strip fuses consists of a metal strip from a lock plate, for currents over 40 amperes. Frequently, these are used in close proximity to starter battery fuse boxes. They are used also in electric vehicles, e.g., in forklift trucks. Because strip fuses require the use of tools for replacement they are therefore legally considered non-serviceable components for end-users.

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