Hummmm, I'm guessing we installed ours in '82. Still on the original florescent original in one but have had to replace the other maybe five or six times. One trick I learned was when you buy a replacement bulb from Home Deport or Walmart, you can cut the end off the plastic piece of the bulb and rip the wires out of the inside and it comes on faster and maybe lasts longer. I think that's what I have done in the past but I haven't changed one in a couple of years. We're full time liveaboards so the lights have daily use....for 35 years.