The Centennial Light is an incandescent light bulb recognized as the oldest known continuously operating light bulb. It was first illuminated in , and has only been turned off a few brief times since.
It is located at East Avenue, Livermore, California , and is open to public viewing. The handmade lightbulb was originally manufactured by the Shelby Electric Company of Shelby, Ohio , towards the end of the s and donated to the Livermore-Pleasanton Fire Department in It has been relocated several times since and remains in the care of the fire department to this day.
The bulb's longevity has been attributed to the high quality of its manufacture, [ 4 ] it being seldom turned off, [ 5 ] [ 6 ] and its low wattage.
The Centennial Light was originally a watt bulb, but has since dimmed significantly and is now as bright as a 4-watt bulb. That story has been supported by firefighter volunteers of that era. Evidence suggests that the bulb has hung in at least four locations. It was originally hung in in a hose cart house on L Street, [ 12 ] then moved to a garage in downtown Livermore used by the fire and police departments. Its unusual longevity was first noticed in by reporter Mike Dunstan.
In , the fire department moved to Fire Station 6 with the bulb; the bulb socket's cord was severed for fear that unscrewing the bulb could damage it.
