Micro 3 Wedge Fuse — 5A to 15A Range

Q: What does Micro 3 wedge actually mean?
Micro 3 is a low-profile automotive fuse smaller than a standard blade or Micro 2, with three metal wedge blades instead of two. Manufacturers use it where fuse-board space is tight, mostly in later-model vehicles with dense factory wiring. The fuse itself is standardised to ISO 8820-3, so any Micro 3 of the correct amp rating fits any Micro 3 socket.

Q: How do I pick the right amp rating?
Match the fuse to the circuit's normal running current with a little headroom, not to the wire size on its own. The rule of thumb is roughly 125 percent of the load's steady draw. If a device draws 6A steady, a 7.5A fuse is a fair pick.

Q: My fuse keeps blowing. Should I fit a bigger one?
No. A repeat-blowing fuse is telling you the circuit is drawing more current than it was designed for. The real fault is upstream, usually a short, a seized motor, a bad ground, or a device pulling more than the wire is rated for. Fitting a bigger fuse lets the wiring cook off instead of the fuse, which is how vehicle fires start.

Q: What voltage is this rated to?
32V DC per SAE J1284. That covers standard 12V and 24V vehicle systems with plenty of margin. It is not rated for 48V DC (which needs a 58V-rated fuse) and it is not rated for 240V AC mains work at all.

Q: Is Micro 3 the same as Micro 2?
No. Micro 2 has two blades and a taller body; Micro 3 has three blades and a shorter body. They are not interchangeable in the socket. Check the shape of the fuse position before ordering.

Q: What do the colours mean?
Colours follow the ISO automotive standard so you can identify amp ratings at a glance. On Micro 3 that is tan for 5A, brown for 7.5A, red for 10A, blue for 15A.

Q: How do I test whether a fuse has blown?
Hold the fuse up to light and look through the clear housing for a broken metal strip, or check for continuity with a multimeter across the two exposed test points on top. A dedicated fuse tester slots straight into the fuse board and lights up if the position is dead.

Q: Can I use these in a boat?
Automotive fuses are fine in a dry marine console. In wet or salt-exposed positions we recommend either a sealed fuse holder or a marine-rated fuse block, since the exposed blade contacts corrode quickly in salt air.

Q: Are these fast blow or slow blow?
Fast blow. Standard automotive blade and wedge fuses all break the circuit quickly when current exceeds the rating. Slow-blow behaviour is only found on MIDI, MEGA and specialty circuit types, not on Micro 3.