So that's how those cheater boxes work, and it also explains why we can't use them here in Downunder. Our singe phase lime voltage is 240v and we don't split it to make 110 opposite phase. We get our 240v 1Ph by splitting the 3 ph to neutral so all we get is 3x240v
Yup, pretty simple really. I'd happily trade for 3 phase though.
I forgot to mention with my extension cord, it's a 12G that I cut the ends off of and wired for 220V without neutral. It works well for most 220V stuff as they usually don't use 110V, so don't need the neutral. So it's hot/hot/ground using 220V connectors on the ends so there's no doubt what it is. I don't use it as much these days as I have a 220V outlet in the garage now.
I'm seriously considering running a subpanel in the garage. Between shop tools and an EV I have a lot of power needs in there.