Written by: Suzie Murdock

This year, I plugged in my Christmas lights only to find that one strand – out of eight – would illuminate. Somewhere within each of the seven strands of light bulbs, there was a culprit incandescent. Before launching into the 2-hour afternoon project, I decided that enough was enough – I was switching to LEDs this year. As an electrical design engineer at Motz Engineering, I am accustomed to selecting LED light fixtures for our design projects. Because of their reduced energy usage, utility rebate options, and a significant increase in lifetime hours of operation, it’s a no-brainer for my clients’ projects; so why not for my Christmas Tree?

This is slightly easier said, than done. With all of the options; color changing, twinkling, snowflake shape, multi-color, it’s amazing that we can even settle on a type for O Tannenbaum. One can easily spend hours sifting through all the name-brand options while searching for the perfect LED solution to mimic their childhood trees. Personally, I grew up with huge, multi-color bulbs – the kind that if left on for too long, the entire house (including our presents) were at risk for a righteous, blazin’ inferno. But sadly, there are no LED solutions for happy golden days of yore. So, white light bulbs it is. However, I have stumbled onto an LED characteristic that is puzzling today’s Christmas Tree Enthusiasts – LED white light bulbs are not all created equal.

Warm white, cool white, and super cool white, if you’re not careful, you’re suddenly giving the “Blue” in “Blue Christmas” a completely new meaning, but why? Why can’t LEDs have consistent hues? It is their semiconductor. Light-emitting diode, or LED, is a two-lead semiconductor light source, and depending on the energy band gap of the selected semiconductor, the color temperature (or hue) will change ever so slightly. The two most common semiconductors used for LED light fixtures are indium gallium nitride (InGaN) and aluminum gallium indium phosphide (AlGaInP). The latter material is used most commonly used for white light hues, and variations in the thickness of the phosphor coating will yield variations in energy band gap or color temperature. Most commonly, instead of listing the LED fixture by their phosphor coating type and thickness, the manufactures will indicate the color temperature in Kelvin (K). For a warmer, more golden light fixture, select a 2700K color temperature. For a cooler light fixture, select a fixture with at 4500K color temperature. Although the science is cool, how do I put it into practice? Let’s check out the following chart:

After evaluating all of my options at the store, I settled on the warmest of all of the options; a cool 3000K color temperature twinkling strand of LED Christmas lights. Although not ideally replicating the golden days of my childhood memories, the twinkling effects, the extremely low cost ($15 for fifty feet), and the 25,000 hours of operating life (25 Christmas Seasons!!) are all I need to avoid a Blue Christmas.

One Reply to “I’ll have a Blue (Tree) Christmas, Without Incandescent Bulbs”

  1. karen amend


    I just read Suzie’s Christmas tree light blog. Suzie, where were you five years ago? I loved your article and the logical explanation for the labeling of LEDs and the results in lights.

    Five years ago I had to purchase light fixtures for my remodeled bathrooms. I had legal sheets of information about Kelvins, wattages, etc. Professionally I am a trained English teacher so electrical engineering was way above my pay grade.

    Thanks for the Blog. I will pass on to my women friends who like me have spend a lot of time only to “just buy something” and go home.

    Karen Amend, Development Director Little Sisters of the Poor

Leave a Reply

Your email address will not be published. Required fields are marked *