 The relationships above are valid for only a few percent change of voltage around standard rated conditions, but they indicate that a lamp operated at low voltage could last much longer than at rated voltage, albeit with greatly reduced light output.The "Centennial Light" is a light bulb that is accepted by the "Guinness Book of World Records" as having been burning almost continuously at a fire station in Livermore, California, since 1901.However, the bulb emits the equivalent light of a four watt bulb.