Outlet was an unused 2 phase job located behind the fridge, unused by us, but wired in series to the switch and then overhead light. Turn on the switch for the light and the increased load on the outlet would make the loose connection arc. As it was an unused 2 phase outlet (made redundant by the 3 phase outlet not more than 2 feet away), we just opened the box and tied off the connection, eliminating the outlet all together and covering it with a face plate. Electrician averted.
The remaining connections were all checked and were snug, so close the book on the sizzling lights mystery, and I don't need to demo my nice new ceiling. Don't you just love old homes?
Rode to work yesterday and today...put a total of 22 miles on the books.