"Don Y" wrote in message
...

Who said it was "20A equipment"?

I have a 100ft spool of 12/3 and another of 10/3. Both are
capable of supporting 20A loads. Both have 20A *plugs*.
Does this mean I can never use the *wire* to support a 15A
device on a 15A outlet? Should I have to remove the 20A
plug and replace it with a 15A plug when using it in such a
situation? Or, replace the 15A *outlet* (which might only
be on a 15A branch circuit) with a 20A outlet for that
duration?

YOur spools of wire are not rated for what you think they are. While the
wire will carry the current, there is enough voltage drop that you should
not be using them at 20 amps.

100 feet of # 12 should be used for up to 12 amps and 100 feet of # 10
should be used up to 15 amps from a wire chart I looked at.