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I have 2 strings of small led Christmas lights above my cabinets in the kitchen as a accent lighting (probably about 100 bulbs total) I have each hooked up to a lamp timer, and they turn on for about 6 hours a night. A friend at work laughed and said that it would be cheaper to leave the lights on 24 hours a day then to run the timers. I can not find a definitive answer, but it makes sense. Anyone know?

  • The thought is that a traditional mechanical timer with a clock motor might use more power than the lights. With an electronic timer it probably more equal power wise. I wouldn't want them on 24 hours in my house but that because of the layout of the house. – Tyson Oct 1 '17 at 19:53
  • 100 Christmas stringer LED mini lights use about 7-9 watts total, the equivalent of an incandescent night light. As Tyson indicated, a motorized timer might be more and an electronic one will use something. LED Christmas lights don't use enough power to make a difference on your electric bill, and turning them off won't save the planet. Control the lights if you want to time the appearance, but don't bother doing it to lower your electric bill. If you only want them on when the room is dark, you could use a light sensor instead of a timer. – fixer1234 Oct 1 '17 at 20:05
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No, the lights will use many more times the power that a timer, digital or analog, uses. If you talk about digital timers, the difference is astronomical. A modern solid-state timer will use no more than half a watt (5v logic x 100ma consumption), probably a lot less.

In terms of mechanical timers, it's still a lot lower than 7w; Using a kill-a-watt, I just now plugged in all 4 mechanical timers I had around (at once), and the meter was still unable to measure the draw, placing all 4 at under 3 watts combined. There are different brands in that batch as well: 1 intermatic, 2 ikea, and one unknown. Think how long a tiny battery can power a mechanical watch; clocks are low-power these days.

Obviously 7w > (x/<3), so your friend is simply wrong. He's a lot closer than he would have been 5 years ago, but he's still wrong.

  • How much does a timer cost? – Edwin Oct 1 '17 at 22:04
  • @Edwin: i only personally bought the ikea ones, they were about 2/$5 if I recall, but question is re: cost to "run the timers" right?. Still, if you saved all 7 watts, the timers pay for themselves in less than year. 1 year @ 16h/day: ((7*16)*(0.2/1000))*365 = $8.17/year power savings at $0.20/kwh. – dandavis Oct 1 '17 at 22:08
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Stick a Kill-a-Watt on the string, but don't be surprised if both strings take 7 watts to run. Go measure it (or read it off the box). Rule of thumb is running a load 24x7 costs $1 per watt per year in electricity.

Suppose you spend $2 a year switching the lights on/off, or $7 a year running them 24x7, then switching is a net lose if switching costs more than $5 a year. So it depends on how much you're paying for timers and how long they last.

  • My line of thinking is if a timer is $10 and lasts for 2 years, you're – Harper Oct 2 '17 at 4:23
  • @Harper: pessimistic? my ikea tandas cost about $2.50 and have been in operation for 7 years so far... – dandavis Oct 2 '17 at 5:37

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