LEDs, yea or nay?
- Thread starter bluesmoke...oops
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heres a link.http://ieeexplore.ieee.org/Xplore/l...0974356.pdf?arnumber=974356&authDecision=-203
http://www.cens.com/cens/html/en/news/news_inner_29710.html
something to do with the electronic ballast that run the 35watt metal halide lamps so that are instant restrike
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dbuckley
Senior Member
- Location
- Canterbury, New Zealand
In the world of theatre the question of "are LEDs good enough yet" is constantly being asked, and decent LED lighting has for several years been "just around the corner".
In many peoples opinion we've now turned that corner; LEDs are good enough, and are getting better all the time. In many applications, LEDs can keep up with 575W incandescent and 250W discharge fixtures. Where deep colours are involved the LED has an even greater advantage.
Maybe for theatrical applications the incandescent bulb has less than two decades before they'll be ancient history.
Although these LD fixtures are apparently exxpensive, over a few years they are actually free, based on the electricity they save.
In many peoples opinion we've now turned that corner; LEDs are good enough, and are getting better all the time. In many applications, LEDs can keep up with 575W incandescent and 250W discharge fixtures. Where deep colours are involved the LED has an even greater advantage.
Maybe for theatrical applications the incandescent bulb has less than two decades before they'll be ancient history.
Although these LD fixtures are apparently exxpensive, over a few years they are actually free, based on the electricity they save.
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
LEDs are quite good enough for striplights and some types of fills. Been using them for a few years, now. It's really nice to get completely variable color on a cyc with the dmx-controlled units. Where LEDs aren't good enough is lights that need a good pattern (ERS/"leko"/pattern spots). I expect those will be incandescent until the LEDs are smaller or somebody comes up with a condenser assembly to go with a bank of LEDs.
Neither. LED is too limited and not any better than CFL for efficiency. T5 and T8 is still more efficient and much higher quality light (CRI). LED's are fine for specific purposes like flashlights, or landscape special effects, but not good for area and interior lighting.
- Location
- Massachusetts
Please do not tell that to our customers.
http://lithonia.acuitybrands.com/Files/RTLED_Files/RTLED_CaseStudy_ChesnutHill_Grocery.pdf
http://vmsd.com/content/star-market-chestnut-hill-mass
They purchased the lighting package, we only installed what they wanted.
We have also replaced at least a couple thousand 6' T12 HO lamps with LEDs in another grocery chains frozzen food cases. They work well.
I was shocked to find out how cheap acuity is letting LED can lights go for. The idea that they cost a premium price is no longer true.
Steve
Ok Iwire as I look at the pix in your link all those lights on ceiling look like tubes (T5HO or T8 ?) to me? Am I wrong?
I have NO PROBLEM installing what the customer wants. I am an ole fart.
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BullsnPyrs
Senior Member
- Location
- Saint Joe, Arkansas
We did a sample store in Pittsburg with a GE case light that really worked well. The project never went ahead because of slow rebate payments by the local utility.
BullsnPyrs
Senior Member
- Location
- Saint Joe, Arkansas
We did a sample store in Pittsburg with a GE case light that really worked well. The project never went ahead because of slow rebate payments by the local utility.
- Location
- Massachusetts
No 100% LED.
weressl
Esteemed Member
Can you be more specific, like the type of fixture, quantity and $?
Ok Iwire as I look at the pix in your link all those lights on ceiling look like tubes (T5HO or T8 ?) to me? Am I wrong?
That's the RT5 LED. They do make a T5 (and probably a T8) fixture just like it. If you take the lens off, there is a row of LED's where you would normally see the lamps.
You probably couldn't tell the difference without taking the lens off, although I've never seen the LED and fluorescent side by side.
Nope, I've said too much already
Just kidding. I normally spec. Acuity's Gotham fluorescent cans. They are a spec. grade can light. The Gotham LED's are also spec. grade, and very similar in price.
But if you give up the spec. grade, and go with the Lithonia Commercial LED cans, you can get them for about 1/4 the price of the Gotham fixtures.
Lamp included, dimming with any old incandescent dimmer, instant on...how can you guys not like them??
Bob do you know the efficacy or true lumens/w?
- Location
- Massachusetts
No, I do not know much about it at all. The customer supplied all fixtures and lamps, we just installed them.
But I do know they were adamant to have it all LED, many punch list items had to do with retro fitting equipment that came in with other than LED.
We also had to retrofit the existing mechanical spaces with LED, mostly converting 4' T8 fixtures to LED by using an LED 'tube' that fit into the T8 lamp sockets.
I think they are counting on the appearance of being 'Green' to add to the ROI. The store is located in the right kind of neighborhood to push that image. They also have a 400 KW full time fuel cell, the second one we have installed in a Supermarket.
thewiseguy31
Member
how did the stand-alone tubes work? i have a distributor with a UL listed tube and I have been asked to do some samples in a grocery store aisle.
BullsnPyrs
Senior Member
- Location
- Saint Joe, Arkansas
Different products have very different results. The LED tubes designed to replace a linear fluorescent tend to be problematic. The optics really do not work well in the fixture and the cost is outrageous.
Bob in all honesty it has been about a year since I last visited LED's, so I am open to the idea they have improved considerably.
Now with that said the manufactures play a lot of game with LED's rating especially efficiency. They flat out misinform.
One when they state the lumens/w they do not include the driver power consumption. LED's are current devices. If the driver is a shunt linear regulator current in = current out. So if the source is DC say 12 VDC and the LED is rated .35 amps at 3 volts for a 1 watt lamp, the driver uses (12 volts - 9 volts) x .35 amps = 3.15 watts. So now that 140 lumens per watt turns into 140 / 4.15 watts = 34 lumens per watt. A plain ole incandescent bulb can do that.
Next is the way they measure the light output. They use a pulse measured at 1 meter in the focal point of the LED on a cold LED. Well two things are wrong with that. LED light intensity drops off sharply when they heat up. Second LED light is highly directional which is great for a flashlight, but poor for area lighting. Move a few degrees off th efocal point and the light level drops sharply.
Lastly is the CRI. LED have a lot of Blue Light pollution.
So with that I have not been impressed with them as of yet. I think one day LED will be in the mainstream , and maybe those problems have been addressed already. So if someone got some credible info I would like to see it.
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