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Thread: LED Lights Power Draw Measured

  1. #1
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    LED Lights Power Draw Measured

    My shop is lit by 4 ft x 2 tube fluorescent lights. They have 32 watt lamps (T8) with new blasts in 2011. In 2016 I replaced one fixture with a 4 ft LED from Lowes. There may be some loss of brightness in both types over time but since these are all at least a year old they are reasonable representations of what I can expect. (my shop time is about 16 hours/week) The LED is as close to exactly the same light output as the fluorescents as I can judge by eye.

    Am I saving enough power to make it worth replacing the other 6 fixtures? Based on literature, sales and scientific, the answers range from "no savings because fluorescent is good also" to "these lights will cut your electricity bill in half"

    This week I got a Kill-a-watt power meter.

    51 watts flourescent

    37 watts LED

    14 watts x 16 hours/week x 52 weeks/year x .1717$/kwh = $2 per year per fixture.

    This is not a big savings, however since the fluorescent tubes burn out pretty often, I may do it.

  2. #2
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    I replaced 72 fluorescent 4 bulb 4' troffers at church (288 bulbs) and applied for a commercial energy rebate from our local provider, DTE. They allowed a standard 112 watts per fixture (pre change-out) and the new bulbs being 12.5 watts each reduced the draw to 50 watts per fixture. That totals to 4.464 kw reduction in load. It netted us nearly $650 in rebates, or $2.25 per bulb. Interesting that in your case and ours, actual wattage is less than the sum of the fluorescent bulbs stated wattage. Edit: All ballasts were removed, as required by the incentive program.
    Last edited by Ole Anderson; 03-07-2018 at 9:08 AM.
    NOW you tell me...

  3. #3
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    I would do them one at a time as the bulbs/ballasts burn out. But then they will not match because by the end you can no longer buy the same fixtures. Or just replace the bulbs and keep the fixtures.
    Bill

  4. #4
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    I changed mine out. I used the existing fixtures and used the ones that bypassed the ballast

  5. #5
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    All my shop lights are now LED. Some are totally new fixtures and some are the same old T12 fixtures with LED "tubes"...all LED for me is from Costco. The level of light is very striking since this change and I really haven't worried about whether or not there's any money savings. There likely is in my case since I was replacing older T12s, however.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  6. #6
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    My new shop is 100% LED bulbs in 8 foot, 4 tube T-8 fixtures. I don't care much about saving money. I am just tired of changing out fluorescent bulbs all the time.
    Last edited by Art Mann; 03-06-2018 at 7:01 PM.

  7. #7
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    I haven't had LED tubes long enough to judge longevity but 4K tubes sure seem brighter, maybe because they don't have a dust layer yet. I was replacing fluorescent tubes more often than I should have. I've read that fluorescent tubes don't like to be turned on and off several times a day. LEDs don't care. I've been replacing tubes and removing ballasts as the fluorescent tubes get dim or burn out. The last pair of LED tubes I bought from Lowes came with a sticker that says the ballast has been removed and don't put regular fluorescent tubes in this fixture. That seems like a good idea.

  8. #8
    I've switched over to LED's from fluorescents-- and while energy savings did factor in, I've found bigger benefits to be the increased brightness in my shop, no humming/buzzing, and no warm up time. My shop is better insulated at my current place, but my last garage was detached and unheated. in the winter I bet I was lucky to get 70% brightness out of my old fluorescent lights (compared to warmer months) just because they wouldn't fully warm up.

    Last shop, I noticed a huge increase in brightness when switching to LED tubes-- so much so that when I moved, the first thing I did to the new shop was get rid of the fluorescent fixtures and put in 12 evenly spaced 4' LED tubes. It's like an operating room in there-- which is great.
    Licensed Professional Engineer,
    Unlicensed Semi Professional Tinkerer

  9. #9
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    There isn't much of a gain when going from T8 to LED.

    At work I look at the cost reduction every year and we're not there yet.

    At home I have T8 lighting, it would never pay for me to convert to LED unless they drop to about twice the cost of T8 lamps......Regards, Rod.

  10. #10
    The specs on T8 lamps are often misleading. The ballast consumes energy and it's not included in the watts claimed on the bulb -- but the bulb isn't actually using its claimed wattage either; how much it draws depends on the ballast. The brightness of the bulb likewise depends on the ballast. The end result is that some T8s are literally almost 50% brighter than others, and most people have no idea which one they have.

    My big thing is that LEDs can be switched on and off repeatedly without shortening their life, and they come on at full brightness regardless of the temperature. So LEDs work very well with an occupancy sensor switch. Saves energy -- and time and peace of mind. No more fumbling for switches in the dark or worrying about whether you turned the lights off.

  11. #11
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    Quote Originally Posted by Rod Sheridan View Post
    There isn't much of a gain when going from T8 to LED.

    At work I look at the cost reduction every year and we're not there yet.

    At home I have T8 lighting, it would never pay for me to convert to LED unless they drop to about twice the cost of T8 lamps......Regards, Rod.
    Same here. I also have yet to find good name branded 4FT LED lights that put out the 5000K 2900 lumens my Phillips T8 fluorescent bulbs do.
    If at first you don't succeed, redefine success!

  12. #12
    Join Date
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    Upgraded my lighting with 12 of the 4K, 4 ft LED a couple of years ago. At less than $13 per fixture, it was a bargain and eliminated the darker areas of my shop. I had previously used an inadequate number of T-8 fixtures and spot lighting. I believe that the improvement has upgraded my work.
    Rustic? Well, no. That was not my intention!

  13. #13
    I pretty much never have tubes fail, so I guess I'm stuck with them forever. Maybe it's weather? My shop lights tend to be on for several hours about four days a week. I can't find any justification to change existing ones for LED, but the last time I added lighting it was all LED strips.

  14. #14
    Quote Originally Posted by Carlos Alvarez View Post
    I pretty much never have tubes fail,
    +1.

    Buy good T8 bulbs, and they'll last awfully long. These are rated 60k hours:
    https://www.1000bulbs.com/product/92...H-3000612.html

  15. #15
    Honestly I have no idea what I bought. Just what was at Home Depot. I recall failures of the old big tubes decades ago, but haven't replaced a single modern bulb in at least six years, probably longer.

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