Has been lit for 109 years.
The improved incandescent lamp, invented by Adolphe A. Chaillet, was made by the Shelby Electric Company. It is a handblown bulb with carbon filament. Approximate wattage-4 watts. Left burning continuously in firehouse as a nightlight over the fire trucks. For some research test results on a sister bulb at Annapolis follow this link.
The upper limit of the lifespan of one of these:
is 15,000 hours or, if left on, around 1.71 years; it would take 63 fluorescent bulbs to provide light for as long as the Shelby Bulb has – and it is still going.
So the question is, over 100 years, does it take more energy to make and light one Shelby Bulb or make and light 63 fluorescent bulbs and safely dispose of 62 of them?
I suspect the answer is 63 fluorescent bulbs although, admittedly, at 4 watts, the Shelby Bulb would be a little dim.