Are Christmas Lights in Series or Parallel? (Wired)

Why don’t your Christmas lights work? Sadly, in the event of a string of lights going out on your tree, replacing the strand is usually the best option. It’s pretty difficult to find that one bulb that’s causing the problem. However, this is a great time to look at the difference between series and parallel circuits.

https://www.wired.com/2014/12/christmas-lights-series-parallel/