30 May 2018

Estimating the lifespan of a light bulb


When I started shifting from incandescent to LED bulbs, I was curious about the claims of long-term cost-savings.  So when I replaced some in my office, I made a note of the date.

Yesterday one of the above bulbs started to die (recurrent and annoying blinking).  My notes showed an installation date of February 2017, which meant it had lasted about 15 calendar months.  The claim on the package (UR corner) is for 9.1 years of life.  Was I being misled?

I tracked down some source data for the newer model of this bulb and found that it is rated for "11,000 hours of life," or "10 years."  That calculates to 1100 hours = 1 year, or an average usage of 3 hours per day as the standard.  Other sources online use the same standard "Estimated yearly energy costs assume 3 hours of daily use."  Apparently that is an industry standard.

My office bulbs are on about 15 hours/day, so the 9.1 years projected life at 3 hours/day would translate to 22 months at my usage, and the 15-month life of my bulb was a bit brief, but at a unit cost of $2 each in multipacks, it's hard to complain.

5 comments:

  1. CFL and LED bulbs are also sensitive to overheating. They are usually rated in a base-down configuration (shown on the left) allowing the heat to rise away from the electronics embedded in the base (the part that is likely to wear out first). Most people use them in a base up configuration (shown on the right) or even in an enclosed fixture like a can light. This can be a worst-case scenario for the electronics and lead to a shortened life.

    For the longest life, look for whole fixtures designed specifically for LEDs where the heat can be effectively dissipated. Avoid replacement bulbs when possible.

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  2. you can get LED light bulbs at a units cost on one dollar at ... the dollar store!

    I-)

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  3. as a kid, it was 'turn the light out when you leave the room'. at a penny an hour (roughly) as the predicted energy cost of an LED light bulb for a year, i find myself 'leaving the light on' when i leave a room for a short period of time, say 5 or 10 minutes.

    I-)

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  4. just as a reference point, how often did you replace that incandescent light bulb that was replaced by the LED light bulb?

    I-)

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  5. "3 hour on/20 minutes off" power cycle is a baseline that manufacturers can use to compare bulbs. It is supposed to have an L number that explains what percentage of the bulbs should last that long (L95 would mean if you bought 100 bulbs, 95% should last the stated hours ~ low numbers like L50) Sometimes that test results in shorter total hours for the lamp than if it was left on all of the time ~ guess which one the marketers use? (answer ~ usually whichever test yielded the highest number for that lamp goes to the home centers and commercial markets get the lifespan if they ask for it)

    LEDs are electronics and like most electronics in your home benefit from surge protectors. I've lived in two cities that have converted their traffic signals to LED and it is common to see these lamps with a significant portion of the LEDs malfunctioning. I assume there is nothing protecting these lamps from the dirty power.
    Planners also failed to consider that LEDs do not provide heat to keep the snow, ice, and even wild life from obstructing them (this poor planning led to much suffering and a huge extra expense as they had to replace thousands of those tunnel visors with open bottom ones).

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