28 gage wire is rated at 0.226 Amps and you were pushing 3.5 Amps through it. That's 15 times the wire gage current limit and it generated 240 times more heat than the wire is rated for. No wonder your cable got hot, it melted the wire insulation inside the cable and shorted all the wires together. 18 gage wire is the smallest you should use for motor cables with the G540.