OK, I've had a continuing hassle develop w/ the ground in the old barn over the last year or so.
Finally, about two months ago I replaced the ground rod w/ new and all seemed well. As of about a week ago, the gremlin is back--there's enough to light a couple 100W bulbs at not quite full intensity and outlets measure full 125V but not enough current to power motors, etc. Clearly it's the ground as all the 240V gear is fully functional.
It's _extremely_ hard to fathom a new rod can have gone south so quickly and we've had sufficient rain that it certainly is the case of excessively dry ground.
Yesterday I ran a jumper directly from the ground bar in the circuit box to the ground and made no difference whatsoever in the symptoms.
It is _all_ 120V circuits, not just one so seems as though not possible to be a failed breaker not passing current; but for the life of me I can't figure out another common-mode cause...
Anybody got any ideas or ever had such a symptom? I may end up calling the pro on this one...was out just last week to help find a broken underground feeder to another of the outbuildings; too bad the symptom hadn't reared it's head again then or woulda' had him take a look then.