Standard Blade Fuse Kit — 120 Pieces Assorted

Q: What size are these fuses, Standard, Mini or Micro?
These are Standard blade fuses (also written ATC, ATO or ATS), the medium-size automotive family. They're bigger than Mini (ATM) and much bigger than Micro2 (APT). Newer cars often use Mini or Micro2 in the dash, pull one of your existing fuses and compare shape before you buy.

Q: What voltage systems are these safe on?
Standard blade fuses are rated to 32V DC per SAE J1284. That covers 12V and 24V DC systems safely. They're not rated for 48V DC systems, use a 58V-rated fuse there, and they're not rated for mains AC at all.

Q: Why are they colour-coded?
Every Standard blade fuse rating has a fixed industry-standard colour, so you can identify a fuse's amperage at a glance without pulling it out to read the number, useful when you're checking under a dash with a torch. In this kit: 3A violet, 5A tan, 7.5A brown, 10A red, 15A blue, 20A yellow, 25A clear/natural, 30A green.

Q: How do I pick the right amperage for a circuit?
Fuse to the wiring, not to the accessory's peak. A common rule of thumb: pick the smallest fuse that comfortably carries the accessory's normal running current (about 125% of it) while still being well below the wire's own current rating. If the accessory is fused by the manufacturer, use the size they specify.

Q: What happens if I use a fuse with too high an amperage?
The wiring becomes the fuse. A fuse rated well above what the wire can carry lets a fault current flow long enough to overheat the insulation or the wire itself, that's a melted loom, a burnt connector, or worst case a fire. Always size the fuse to the wire and the accessory, not to whatever's in the drawer.

Q: What happens if I use a fuse with too low an amperage?
The circuit works until you turn on the accessory, then the fuse pops, sometimes immediately, sometimes after a few minutes when a motor draws its startup current. Nothing dangerous, just annoying. Step up one rating and try again.

Q: Where can Standard blade fuses go?
Anything that takes a Standard blade fuse holder, vehicle fuse boxes, aftermarket fuse blocks, inline weatherproof fuse holders, dedicated blade fuse panels. If your holder or block accepts a plug-in Standard blade, these fit.

Q: How do I tell if one has blown?
Hold it up to the light, there's a small clear window across the top showing the metal element inside. If the element is bent but continuous, it's fine; if there's a visible gap in it, the fuse is blown. A multimeter across the two prongs (with the fuse out of the circuit) is the definitive test.

Q: Can I re-use a blown fuse if it looks fine?
No, replace with a new one of the same rating. A fuse that has blown has been thermally stressed even if the element looks intact; its behaviour on the next fault won't be reliable. That's what the kit is for.

Q: Why did my fuse blow in the first place?
One of three things: (a) the accessory is drawing more current than the fuse allows, upsized wiring might be needed, and a bigger fuse to suit; (b) a wire or connection somewhere in that circuit has shorted to earth; (c) the accessory itself has failed and is drawing a fault current. Don't just fit a bigger fuse without finding out which one it is.