"Burning" a fuse

[Grady]

My low beam (dip?) headlight (standard wattage) didn't come on. Bad 20 amp fuse. But the fuse didn't just pop; it completely melted one side of the yellow fuse body and left a crumbly carbon residue.

I removed, cleaned, added some di-electric grease and replaced the fuse. The lights work fine, the fuse don't feel hot or smell like electrics cooking around the fuse box.

Fluke or symptom?

Grady

[B@man]

Hi Grady,

This sounds like you may have had a oxidised contact on the fuse which has then got hot due to the current flowing through it which has eventually melted the fuse. Do any of the other fuses have white deposits on their blades ?

[GreenV8S]

Probably a poor contact between the fuse and the holder. If it is a blade style fuse the terminals can gradually relax so they don't clamp properly. If it has been getting hot this can make the problem worse. They can also suffer from corrosion. Just taking the fuse out and replacing it could be enough to scrap the contacts clean for a while.

[Grady]

The other light fuse had a white deposit(?) in the right blade side of the plastic body (same side as the one that burned out) but it tested OK (no resistance). The blade was clean but I changed it out for good measure. The other couple of fuses I checked looked OK but I think I'll pull, clean and reset them all.

Thanks Grady