So a question that I have is why a major winch manufacturer supplies 12' (2x72") of 2ga wire rated at 120a when a winch will pull in excess of 4x that amount
Aye, that's a bloody good question. Using the Warn M8000 as an example:
http://www.warn.com/truck/winches/src/M8000.shtml
They do exactly what is mentioned in the quote - include 6' of #2 wire for a unit which, according to their specs on that page draws up to 435 amps. And in fact, that's not actually the max amp draw. The number they are quoting is the max amp draw while the motor is still turning. The true max amps would be the LRA (Locked Rotor Amps), which is not listed.
So yes...WHY do that they do that, when there is clearly the potential to seriously overload the wire included in the kit?
Dunno. Prolly something to do with cost/benefit vs. return rates or some other manufacturing/marketing formula.
As to wire ampacity charts - I find the ones for 12v applications are often misleading. The reason is that when dealing with the down and dirty low-voltage range of 12v systems, one really has to pay extra attention to voltage drop, which is not nearly as much of an issue up in the 115v/230v range.
So, wire gauge charts for low-voltage systems seem to often be fudged a bit this way or that - especially when produced by manufacturers of devices where their chart is showing the recommended wire gauge for their device.
But the simple fact is this: X wire with Y insulation is rated to handle Z amps at N temperature before the insulation melts. Period.
Proper wire ampacity charts will list not only the gauge of the wire, the also the temperature rating and the wire type (i.e., the insulation type). Any wire chart which does not list those things is, IMHO, suspect.
Here's a proper wire chart:
http://www.armstrongssupply.com/wire_chart.htm
