ATO/ATC Blade Fuse
The ATO/ATC blade fuse, with its two flat blade terminals and transparent plastic body, is the standard protection element of vehicle electronics. It covers ratings between 1 A and 40 A and the body colour is standard for each amperage. Because the body is transparent, the melted element can be seen by eye.
The reason blade fuses became widespread is their practicality: they are fitted and removed by hand, their holder is compact and they hold far better than glass fuses under vibration. Besides the standard ATO/ATC size there are also different body sizes such as mini and maxi; the size of the fuse and its holder must match.
- Colour code: the rating is read from the body colour at a glance; there is usually a diagram on the fuse box lid as well.
- Limit: for currents above 40 A, bolt-body MIDI/MEGA types or strip fuses are used instead of blade fuses.
- Holder quality: loosened holder clips create contact resistance; they cause a voltage drop even without the fuse blowing.
Blade fuses have one more advantage in diagnosis: because the two blade terminals are accessible from outside, you can measure the voltage drop across the fuse without removing it. If the fuse is sound, almost no difference is read between the two terminals; if you see a clear difference, either the fuse has blown or the holder contact has degraded.
Context in which this term is used: Installation, redundancy and field continuity