Quote:
Originally Posted by GreatOldOne
Right - here's a question. If I fit a 60 amp fuse, as Peter has, its rated for 60 amps continuous draw, and will blow at 120 amps.
Does this mean that I would need to run 60 amp cable from the battery to the fuse? The highest rated cable I have is 39 amp (56/030)... and the cables the other side - well, you've seen them in the pic. I'm guessing they're not 60 amp cables.
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How cables are rated is actually quite complex. For example a 39 amp cable will carry far in excess of 39 amps depending on the environment. It would probably take several hundred or even thousand amps to actually "blow it". The fuse is there essentially to protect the cable from overheating, melting the insulation and subsequently causing a fire.
For me I would probably have used a fuse with a lower rating - say 40. But there is a danger of using a fuse of too low a rating - it may be OK for a while but the heating effect caused by excessive current flowing through it will eventually cause it to fail. Is this fuse in the feed to the engine management system? Perhaps someone knows what it should actually be? Unfortunately the in-line fuse BMW fiited in my loom does not have any marking.
Sorry - I just realized that was a non-answer. :-(
Simple (engineers) solution. Fit a smaller fuse and carry a few spares in the car of a slightly higher rating just in case.
Robin