But Dennis don't you find a contradiction in the two points that you've made in this post? First you're saying that the graphic does not show an increase in conductor size due to it's capacity but then you're saying that the OP does show an increase in conductor size so the #12 is no good. Actually the two examples are the same.
I do see the contradiction. This is why this section is very poorly written. In the graphic case I can see why the wire size would be considered increased, however with the op I do not see it as the same scenario.
It appears we can interpret this section to suit our needs if we need to-- I am not saying you are doing that--it is just poorly written. Give the bad job I have to try and understand what the code panel is looking for here.
Unfortunately no matter what you or I decide there is the AHJ who will make this decision.
Let's look at your example again only this time with a pigtail of #6 for 12" to tie on to the #12 back to the panel. Have I increased the size of the ungrounded conductor? I could argue that you would need a #6 ground for 12" then tie it to the #12. At what point would it be considered increased.
