Comments on: LED Lighting – A Primer to Lighting the Future

By: mrmarkjackson

mrmarkjackson — Wed, 21 Nov 2012 16:30:48 +0000

LED Lighting is definitely ready for the home, we've written a guide here on how best to install an LED lighting system at home which includes what the potential advantages are.

By: Bruce

Bruce — Thu, 01 Nov 2012 21:34:03 +0000

Thanks Dan. Lots of great info in your comment, except the part about color temperature of sunlight “Sunlight is well above 10,000K for reference.” Direct sunlight is typically assumed to be 5,750K, though NASA puts it at 5,878K ( http://nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html ). Still, thank you.
Bruce

By: MAKE | LED Lighting – A Primer to Lighting the Future « ElectraLED Blog

Thu, 18 Oct 2012 15:45:49 +0000

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By: sal cangeloso

sal cangeloso — Wed, 22 Aug 2012 20:07:44 +0000

Ha, awesome summary. Totally nailed it.

By: sal cangeloso

sal cangeloso — Wed, 22 Aug 2012 16:30:26 +0000

Thanks Dan!

That number, the L70, is the standard for the lifetime of the bulb. It basically says that after 25,000 hours the bulb will be at 70% of its original brightness. After that point it should continue to operate, until the LEDs or electronics give out. You don’t have to replace it at that point, but you’ll see a noticeable difference. And, you’re right, there is no good way to tell when a bulb is at 70% (or 80% or 50%…) unless you have some sort of measurement tool. This might not matter to some people, but others will probably wonder if they got their money’s worth!

Some high-tech lighting systems will have lamp tracking, so you’ll be able to mark down install days, run time, power consumption, etc. but that’s just for big commercial installations so far. Home automation should be able to tackle it before too long.

Regarding lifetime – There isn’t testing for how long a lamp will last, but the degradation of LEDs over time is linear, so you can do the math and figure out the expected brightness level after x hours of operation.

By: Dan Koss

Dan Koss — Wed, 22 Aug 2012 16:10:07 +0000

Thanks Sal! Great stuff.
One other point on LED that I’m watching carefully is lamp life. It is only calculated at this point and is defined as when the LED dims to 70% of it’s original lumen output. How is anyone supposed to know 70% of lumen output after 5, 10 or 15 years? Unless the lamps (or drivers most likely) fail completely nobody will know when to replace them.

By: Dan Koss

Dan Koss — Wed, 22 Aug 2012 16:07:14 +0000

Hi Tommy,
I am in a field where I specify lighting for a lot of industrial applications and have learned a LOT about CFL bulbs and lighting in general. I had a lot of the same concerns you mention and dug pretty deep into things to figure out how to avoid the same issues you mention. Here’s what I learned:
1. The spiral bulbs that we all think of as CFL bulbs are really only a retrofit. This is important b/c the manufacturers are doing a lot of work in the same space as an incandescent bulb. A true CFL bulb has separate ballast and are usually a lot more robust than the retrofit kind.
2. CFLs have electronic ballasts that are sensitive to power quality. This is true for both retrofit and OEM CFL. Surges and sags in voltage will shorten the life of both the lamp and the ballast. CFLs will hate it if the lights dim when your AC kicks on.
3. Switching will also shorten the life just like an incandescent. Fluorescent lamp life is determined by plugging in a ton of lamps and leaving them on until 50% of them burn out. However long it took for the 50% to die is the determined lamp life. If you switch the lamps on and off a lot the lamps won’t last as long. This is especially true for “instant start” type lamps. To instantly start the lamp the ballast hits it w/ a very large voltage spike. That spike burns up some of the gasses in the lamp and shortens the life. “Program Start” lamps are better than “instant start” b/c they still hit the lamp a little harder to start it but they don’t hit it w/ an entire bus.
4. Wattage is a horrible way to measure brightness. Look for the rated lumens. Lumens are a measure of light out of the lamp. There is a whole lot to learn about lumens and where they are lost but it’s a much better start then wattage. This applies to CFL and LED! A lumen is a lumen.
5. Another deceiving thing about brightness is color. (again, CFL and LED) For the same lumen output a “cooler” color will appear brighter to the human eye. That’s why the first CFL lamps were usually very “cool”, they were perceived as being brighter. The measurement for color is in Kelvins. The higher the Kelvin the cooler the color. The typical incandescent is about 2500K to 3000K. The only reason we prefer that color is because we have grown accustomed to it. Sunlight is well above 10,000K for reference. Typically the higher the Kelvin rating the better the color rendering. The Color Rendering Index (CRI) is only supposed to be used for comparing the color rendering ability of lamps of the same Kelvin rating. That’s not very useful but there isn’t a widely accepted alternative yet. There are plenty of people working on it like Sal mentioned. If you give yourself a change to get used to a 3500K lamp you will probably find you will prefer it to 2500K. That’s personal preference though. You can find both LED and CFL in lower color temps.
To summarize; Retrofits are only band aides to avoid replacing the fixture, power quality is important, excessive switching is bad, lumens = bright, watts = power and $, look for Kelvin ratings if you don’t like blue, take CRI with a grain of salt, and finally CFL isn’t always the best solution but LED has a ways to go and the standard incandescent toaster light is rarely the best solution.

By: ameyring

ameyring — Wed, 22 Aug 2012 12:08:14 +0000

I started changing over to circular CFLs from Lights of America (most affordable bulbs at the time) around 12 years ago and they were junk and a couple of ballasts fried themselves. Changed to GE and was much better.

By: Eugene

Eugene — Wed, 22 Aug 2012 05:21:08 +0000

I think it was Lights of America, something like this: http://www.amazon.com/Lights-America-2326LED-LF3-24FR-2-Watt-Power/dp/B004NYAPXQ/

By: sal cangeloso

sal cangeloso — Wed, 22 Aug 2012 03:40:33 +0000

I found the Philips to be a great choice, specifically the 12.5W AmbientLED. It’s a reasonable price and I’m happy with the performance. I’ve probably only got a few hundred hours on mine, but they are holding up nicely. I’d be curious to know the brand on the ones that burned out prematurely if you remember it.