In practice the lineman risk isn't as real as it seems at first. Odds are when the lineman shutdowns a segment, if your system tries to supply power there are enough other people on the segment that you will trip your local overload protection and isolate the grid.
I don't blame lineman for not wanting to trust that though. My understanding is their practice is to always short out the line when working on them as that is the only way to be 100% sure it isn't live. (note that linemen work on live lines all the time, but when they need a dead line they ensure it is dead)
Agreed. But given what I've seen in some off-grid installations I really don't blame them. And I have seen one installation that tried to supply all of Ontario when it didn't go off-line as it should have, that wasn't a really pretty sight. The inverter died quite spectacularly, judging by the scorch marks on the wall above it, all of the magic smoke had definitely gone out of that one.
I don't blame lineman for not wanting to trust that though. My understanding is their practice is to always short out the line when working on them as that is the only way to be 100% sure it isn't live. (note that linemen work on live lines all the time, but when they need a dead line they ensure it is dead)