My wife and I went shopping at the local hardware store for something completely random, and instead bought a pre-lit 6.5′ christmas tree. Normally $170, marked down to… wait for it… $10! Sold. Anyway, it came pre-lit with 300 mini incandescent lights. There was no option for an unlit tree at that cost, so we figured we’d just “unlight” it, and relight it. But before that, I thought I’d use my handy Kill-a-Watt (Thinkgeek right now is the cheapest place to get one, otherwise I’ve bought two of them from here) and see how much power 300 mini lights use.
The answer, 102 watts (0.34W/bulb)! That’s 2.448KHW/day (assuming 24 hour use), or $0.1133/day. Damn. Could you imagine the old days when people put C7 (5W/bulb) or C9 (7W/bulb) bulbs on their tree?! No wonder trees used to dry out and catch fire. Let alone the amount of energy a house would use covered in those bulbs.