4000 lumen linear LED light, or two 2000 lumen T8 LED lights?

In my home, we have three 48" fluorescent fixtures. I wish to replace these with LED lights with a high CRI. I am currently planning to use Cree "TrueWhite" lights.

I need to decide between using the Cree drop-in replacement T8 bulbs that run off of a ballast (CRI 90), or the Cree Linear LS4 (CRI 92), or some third option.

I've never seen a Cree LS4, just photos of it. It's the size of a single fluorescent bulb but as bright as two bulbs (4000 lumens). I'm wondering if it will be too bright and will annoy us, or if it will be fine.

Two of the lights I need to replace are in the kitchen. In the ceiling there are two long rectangular boxes, with a fluorescent fixture inside each (T12 bulbs) and a plastic diffuser panel. If I stick an LS4 inside each, will it look about the same as if I put a pair of Cree T8 bulbs, or will it seem harsh?

The other light is in the master bathroom, over the mirror, inside a smooth white diffuser. (It looks like a Lithonia Litepuff vanity light as shown on the Home Depot web site.) Currently the whole thing glows pretty evenly... with a single tube at twice the brightness would it look different?

I would actually prefer to have a custom power supply designed for LEDs, rather than using the Cree T8 bulbs with a fluorescent ballast, but perhaps I'm being silly.

If you have a third option to suggest, please do so. But please don't suggest I just switch to high-efficiency fluorescent bulbs; we want to use LED lights.

Also, what color temperature do you suggest for kitchen and bathroom? I was planning to go with 3500K for both.

Thanks in advance for any advice you can give me.

Links to the various products discussed in my question.

Cree T8 bulb: http://www.cree.com/Lighting/Products/Indoor/Lamps/T8-Series

Cree Linear LS4: http://www.cree.com/Lighting/Products/Indoor/Surface-Ambient/LS-Series

Lithonia Litepuff vanity fixture: http://www.lithonia.com/commercial/litepuff+vanity.html#.VFqtKfnF92A

The kitchen light installation looks similar to the one shown in this image: http://www.irepairhome.com/wp-content/uploads/2013/04/112-147-kitchen-fluorescent-light-fixtures.jpg

steveha said:

...don't suggest I just switch to high-efficiency fluorescent bulbs; we want to use LED lights...

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Just curious - why?

brickbat said:

Just curious - why?

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Oh, the usual reasons I'm sure: guaranteed silent operation (we have one fluorescent ballast that buzzes annoyingly), extra reliability (after a decade or two LEDs won't be quite as bright as when new, but they usually don't just burn out like a fluorescent tube can), and a possibly-irrational desire to get every last mercury vapor tube out of our house.

Also I have read that there are fluorescent bulbs with a CRI of 90 but the spectral charts I have seen for fluorescents show much more spikiness than LED spectral charts, so I suspect that LEDs will have more pleasing light than even a CRI 90 fluorescent. http://www.designingwithleds.com/review-hands-cree-linear-led-t8-fluorescent-replacement-lamp/

And the most important reason: I have already bought Cree "TrueWhite" bulbs (incandescent bulb replacements) and I like the light, so I'm trusting Cree to make similarly nice light for fluorescent replacements.

It is possible that we could save a few Watts by going with fluorescent T8 over LED lights, but this is our home and it's only three lights, so I don't need to go for max efficiency. I just want really nice and pleasant lights that will last a long time.

I re-read the specs on the LS4, and I realized that I was completely mistaken about its size. It's not the size of one fluorescent tube; it's 3" by 2.5", making it roughly the same size as other T8 fixtures with two tubes.

So my fears that it would be a really skinny thing that emits a painfully bright light seem silly now.

I went ahead and ordered the LS4... once it arrives and the electrician installs it, I'll try to remember to post a follow-on here about how it worked out.

steveha said:

I've never seen a Cree LS4, just photos of it.

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I have one. It puts out as much light as a 250W halogen. As to whether it would be too bright for you, I am not really sure. It is a little bright, but not extremely so. Somewhere in the middle to answer your question.

I am not sure about installing two of these fixtures in your kitchen. It might be a little bright in there. But the LS4 is dimmable, if you want to install a dimmer circuit (there are additional wires inside that you will have to attach).

If you do buy one, just be aware that installing it can take a little trouble. It comes with bare wires that you will have to attach, and to access those wires to begin with you will have to first pry the lamp apart, which can take quite a bit of effort. You may likely need 2 people to help you.

Also, do not be expecting anything magical. Although Cree TrueWhite technology does make the background look a little more colorful and adds some depth to the warm colors, the light still has the basic aura of a fluorescent.*

It might make more sense for you to just get some high CRI Cree downlighting, if you're willing to rip up the ceiling.

steveha said:

Also, what color temperature do you suggest? I was planning to go with 3500K.

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Well, if you look at a spectral graph for a TrueWhite LED lamp, it seems apparent that it probably provides better quality at lower color temperatures. Since it is missing that blue-green light that should be more prominent at higher color temperatures. (I think regular fluorescents do better at higher color temperatures, btw)


*Also a minor little thing, not sure about other Cree TrueWhite products, but the Cree LS uses a 440nm emitter, which can make the light seem just a little harsher than other standard LED lamps. Just my subjective observation.

Home Depot has just started offering (2) new 48" bulbs that are priced at $24.95 each.
Here are some links:
3000K
http://www.homedepot.com/p/3NLED-4-...inear-LED-Tube-Light-Bulb-SNT8B-12S/205496131

5000K
http://www.homedepot.com/p/3NLED-4-...inear-LED-Tube-Light-Bulb-SNT8B-12S/205494182

The kitchen was designed with four 48-inch T12 fluorescent bulbs. I'm going to try two Cree LS4 fixtures and see how we like it. Yes, if we decide it is too bright, we may use some sort of dimmer.

Given the very long life of LEDs, we will be using these lights for many years to come; so I want the best ones I can get. I made the decision not to consider the Home Depot bulbs as they have a CRI of 80 (vs. a CRI of 92 for the Cree LS4).

I'm puzzled by the spectral chart, which looks different from the spectral chart published with the Cree T8 replacement bulbs review: http://www.designingwithleds.com/wp-content/uploads/2014/05/Cree-T8-2-tubes-turn-on_wR9-600x316.jpg

I'm assuming and hoping that the LS4 fixture will have a spectrum at least as nice as that spectrum.

steveha said:

I made the decision not to consider the Home Depot bulbs as they have a CRI of 80 (vs. a CRI of 92 for the Cree LS4)

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When it comes to LED, the difference between 80 CRI and TrueWhite 92 CRI is basically just that warmer colors look a little "fuller". The reds do not really look more red, it is just that they appear a little brighter. Also, the white light from the TrueWhite looks a little more orange-tinted, how it should be, rather than yellow-tinted from an 80CRI LED
(by contrast, low color temperature fluorescents usually seem ugly pink-tinted).

Another thing, if you are going with low color temperatures (3000K to 3500K), green colors are rendered a little better with the TrueWhite than regular 80 CRI LED. But for higher color temperatures there is no difference here. My 3500K TrueWhite LS4 renders greens no better than a 5000K regular LED. This is not surprising, since basically a 3500K TrueWhite has the same green-shifted phosphor of a 5000K LED. (maybe not exactly but you know what I mean)

I am not really sure if the difference in light quality is very big. But if you are going to have the fixture for a long time in a place you often use, any small improvement can be important. Many plain phosphor based LED downlight products are becoming available that achieve 90 CRI without the need for separate red emitters.

The lights are installed. I am completely happy with them.

The kitchen is now a little too bright. We can live with it but I plan to have dimmer(s) installed to dim the lights... two lights at 4000 lumens each is more than necessary. (I wonder if the original 48-inch fluorescent lights were less than 4000 lumens when new?) The lights are bright but not as glaringly harsh as I feared, and when they are behind the diffuser panel they look okay. You can see a brighter section where the light is, but it's not horrible. I guess if Martha Stuart ever comes to grade the decor of my kitchen she would dock a few points but I think I can live with it.

The kitchen light looks a little yellow, but the diffuser panels are two decades old; I plan to buy new ones and I think the color will then be perfect.

The bathroom fixture is now upgraded, and I think it is just perfect. I like the "LitePuff" diffuser and that is still there, but now the quality of light is better, it's brighter, and it's completely silent.

In summary, I would buy the Cree Linear LS4 lights again, and I recommend them.

Anders Hoveland said:

if you look at a spectral graph for a TrueWhite LED lamp, it seems apparent that it probably provides better quality at lower color temperatures.

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Correction: This might not be true. As I have later found out, the higher color temperature TrueWhite uses more greenish shifted phosphor, so it may just be the complete reverse.
I can actually make out the reddish-orange line in the spectra of a 4000K TrueWhite, whereas with a 3500K, it is difficult to discern, appearing all blended in with the broad range of colors from the phosphor, the phosphor is shifted more toward the yellow so there is more overlap.