I use SPT1 in many areas and many pull more than 10A with no trouble. Some are closer to 15 and I have yet to melt a wire. I wouldn't use it like this for an inside extension cord but for outside temp holiday lighting, I have no fear of it. As part of my load testing, I let the display run for about an hour or so and then pick up the wire. If it doesn't burn my hand then it's good to go. Last year we had some snow and the wires cleared the snow from themselves by the second day.
