Collection: Standard Fuses (19mm)

The ATO/ATC fuse: the modern automotive standard

Introduced in 1976 and widely adopted in the 1980s, the ATO blade fuse (19 mm high, transparent or colored plastic body, central metal blade) has become the global standard for automotive electrical protection. Its transparent or semi-transparent body allows for visual inspection of the filament's condition—a practical advantage for quick roadside diagnosis.

ATO vs. ATC difference: ATO (Auto Type Open) refers to the version with an exposed filament not protected against moisture; ATC (Auto Type Closed) incorporates a slightly more sealed closed housing. Both formats are physically and electrically interchangeable.

ATO fuse color code: read the amperage at a glance

The blade fuse color code is internationally standardized—it is identical for Bosma, Bosch, Littelfuse, or any other manufacturer:

• Violet = 3 A
• Pink = 4 A
• Tan (light orange) = 5 A
• Brown = 7.5 A
• Red = 10 A
• Blue = 15 A
• Yellow = 20 A
• Clear transparent = 25 A
• Green = 30 A
• Orange = 40 A

Choosing the right amperage: absolute safety rule

The fuse protects the circuit (the wire), not the connected equipment: it must blow before the wire heats up to the point of catching fire. Always respect the amperage indicated in the wiring diagram or on the fuse box cover. Never exceed the original amperage—a 20A fuse in place of a 10A fuse allows double the current to pass and can melt the wire itself. And of course: never use makeshift fuses (wire, aluminum foil, screws, etc.)—extremely dangerous, with an immediate risk of fire.