Given that I don't have neutral, sounds like, even for just running a simple irrigation controller, that I don't want to use the ground wire for my neutral and simply pull 120v off the split phase 240V since a potential short would energize the ground wire.
It seems like running a small transformer is the way to go. However often recommendations I have found mention adding a sub panel breaker after the transformer, which seems like overkill for my need. Would adding a 5A fuse to new transformed 120V be fine instead of a whole breaker box?
I'm surprised how much transformers are, and most of them are for transforming single phase Euro 220v to US 110v, anyone have a good source?
As an aside, if this existing ground to the 240V did connect directly to ground at the main panel instead of neutral (haven't looked yet, in the neighbor's panel) then to me it would be ok to just pull L1 and ground off the 240V and skip the transformer right? These are very large wires running a 20A load to a well pump, might 1000' away, so I think this is the only load on that breaker.