Quote:
Originally Posted by davids2toys
Maybe I am an idiot but I still do not understand what you used when you say "40amp". Was this the fusible link wire I am looking at online? As I said, 40 amp equals a 22 gauge wire, so I am still not understanding what you used. So are you saying 16 gage fusible link wire(75 amp) is OK, but not for you? You would go with the 22gage(40amp)fusible link wire???  |
As you know, but I'll say it anyway, when an electric motor is turned on, there will be an initial, very large "surge" of current that will exceed the rating of the fuse. But, the fuse or circuit breaker won't blow because it takes a little more time than that to heat up the element and cause the trip. This is normal. For a dramatic demonstration, go here:
300 amp X 12 volt Circuit breaker and skip down to my post with the pic of my inductive ammeter set to measure the surge current of my starter motor (and it's the old style big guy that went in to five billion Ford cars). Yep,
over 900 amps. So you know, any of our cars, even the ones with the little tiny 60 amp alternators like mine, can still crank out hundreds of amps, which can create enough heat to melt any of your wires. In choosing a fusible link, the reason you go with a gauge rating, instead of an amp rating, is because you are protecting the wire itself, as opposed to the load. A fuse will protect the load, so it's handy to just double the amperage for the load and set that as your fuse value -- even if you're feeding the load with a very, very large wire, or a small wire. Now with a fusible link, you ask yourself
"what's the maximum amperage that wire will handle" and then place a fusible link along the line that will handle less than that but, of course, still exceed the combined load that is being served by the line itself. Most car wires, if you short them to ground, will carry quite a bit of amperage before they burn the insulation up -- much more than you might think.
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