How long do incandescent Christmas tree lights last?

September 24, 2020

Short Answer: Incandescent Christmas lights (the glass kind with filaments) last about 3000 hours.

Longer Answer: Because incandescent Christmas lights generate heat by heating up a tiny filament, their lifespan is not as long as their LED counterparts.

Expect about 3000 hours which is about 125 days or a little over 4 months of operation if you leave your lights continuously plugged in.

(We actually suggest you turn off your lights during the day, and after it gets late to extend the lifespan of your light strings.)

The following environmental conditions can shorten the life of your light strings:

  • Exposure to weather extremes – either too hot and too cold
  • Exposure to salt in the air. Beach living is hard on lights and anything else stored outside (or inside for that matter!)
  • Exposure to snow
  • Critters and squirrels chewing the wires
  • Installation location where wind can move the stings and cause rubbing that will put wear and tear on the wiring
  • Sun exposure will take a toll on the insulation
  • Surges and fluctuations in the electrical supply
  • Quality of electrical power source – hydroelectric and geothermal power generation generally have more impulses than coal, natural gas, or nuclear power generation

Our favorite tip for extending the lifespan of your incandescent Christmas lights is to replace burned out bulbs as soon as you notice failures. Each bulb that is burned out uses less electricity which is distributed to the lit bulbs. Too many burned-out bulbs and your lights will experience cascade failure.

Be sure to replace burned out bulbs at the end of each season. If you purchase a large number of light strings of a single type, consider purchasing one extra strand to be a future source of replacement bulbs.

Hope this helps. Have any questions? Post them in the comments below.

Shellie Gardner
Aside from throwing dinner parties that feature at least two kinds of cheese dip, Shellie's passions include travel, Mid-Century Modern furnishings and finding the perfect street taco. Has been known to snort laugh champagne.

2 thoughts on “How long do incandescent Christmas tree lights last?”

  1. Can the Incandescent bulbs be replaced with the new LED lights on the old stringers We are looking to replace all our bulbs

    1. Not in small Christmas tree light strings like these: mini lights

      Now, if by stringers, you mean C7 or C9 bulbs and cords, then if the cords are in good condition, you can replace your glass bulbs with LED. Be sure not to exceed the maximum length rating of your cord regardless of the bulb type.

      Those would be this type of bulbs and cords. Take a quick look to see if this style matches your set.

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