Are you interested in LED light?

[Pano]

Originally Posted by tvrgeek

Except it is not a vacuum tube. If under 40W, it is full of dry air. Over 40 usually nitrogen.

Uhhhh..... you may want to read up on that one. (Hint: wrong on both counts)

[jitter]

Originally Posted by ztlights

I would like to know your opinion about led light, do you think it is necessary for us to change our traditional light into LED light for saving more energy and cost.

I think it's both necessary and inevitable. Incandescent bulbs have largely been phased out over here.

I can think of a few reasons why LED is the future of lighting:

LED-bulbs that are designed to be a replacement for incandescents are now becoming more efficient than their predecessor, the CFL. E.g. a 11 W/600 lm CFL (51 lm/W) can be replaced by a 9.5 W/600 lm (63 lm/W) LED-bulb of the same colour rendering and colour temperature.
Of course, total running cost is still higher for a LED bulb, so prices will need to come down some more first.

LEDs do not suffer like CFLs from repeated switching. Each ignition of a CFL seriously shortens its life. I've seen CFLs fail in a high cycle application with only a couple of hundred hours on them. I've also seen CFLs exceed their expected lifetime by a factor of 2 to 3 (!) in on-at-dusk-off-at-dawn type of lighting. On some, the ballast failed before the lamp, and my guess is that LED bulbs with good heatsinking of the LEDs will show the same failure mode.

LEDs do not need a warm up time to give full light output that is so typical of fluorescent (and other types of gas discharge) lighting.

LEDs do not contain mercury.

LEDs for ligting purposes do not have IR or UV in their light beam (LEDs made specifically for emitting UV light do exist, BTW).

IMHO, made-for-LED luminaires are the future of LED lighting. These can make optimal use of the directional spread pattern of LEDs increasing system efficiency (light source + luminaire effeciency).
A high efficacy model for office space ligting was recently introduced by the company that was founded in my hometown. The existing model was already good for 80 lm/W, the HE model does 110 lm/W.

The same company is also making LED lighting sources that gradually change their CCT from 2700 K to 2200 K when being dimmed to create the same effect as dimming an incandescent bulb.

When street lights are at end of life in my city, they are being replaced by LED luminaires. To my surprise the glare from these luminaires is less uncomfortable than I expected (better than HID).

In my own home, I use a mix of (halogen) incandescent, (C)FL and LED, depending on the application.

BTW:
2700 K = warm white light, like incandescent;
3000 K = warm white light, like halogen incandescent;
4000 K = cool white light, standard workspace FL lighting;
6500 K = daylight white, however appears as blueish to the human eye when viewed in low intensity.

[tvrgeek]

Originally Posted by Pano

Uhhhh..... you may want to read up on that one. (Hint: wrong on both counts)

I am going by the GE manual for incandescent lamps, about 400 pages of everything you ever wanted to know. It was about 30 years ago when I studied it, but I do's think much has changed. Doing a bit of WEB research, it looks like vacuum was given up on in about 1913.

[AndrewT]

I have very few (<5%) incandescent of the "old" variety.
I have a lot (~50%) of the halogen type incandescent.
I have a few (~10%) of the long tube fluorescent.
I have a lot (~25%) of the CFL replacement type.
I have a few (~10%) of the LED replacement type.
I have no dedicated/exclusive LED type.

All the "new" have a longer life than the "old"
All the "new" have a higher light to electric efficiency
All the "new" except long tube F have less light than the claimed equivalent incandescent.

It seems much of the bad press and bad reputation for the "new" is down to excessive claims by the proponents.

If we do our research the truth is out there.

I expect light output increase ref same input to be: halogen + 20%, CFL to be +200%, LED to be +400%, Long tube to be +300%, from my experience in domestic use.
I prefer LED replacement to CFL replacement for colour rendition. and halogen for best colour rendition.

BTW,
as with many other stats posted in this Thread which are clearly wrong, white light is not 3000K. Ask any traditional (colour) photographer for the correct answer.

[Mooly]

Originally Posted by AndrewT

BTW,
as with many other stats posted in this Thread which are clearly wrong, white light is not 3000K. Ask any traditional (colour) photographer for the correct answer.

Not just photography. I hope you have your TV white balance set correctly too. Illuminant D

[Pano]

Originally Posted by tvrgeek

Doing a bit of WEB research, it looks like vacuum was given up on in about 1913.

For lager lamps, yes. Only the very small ones use vacuum these days. Most common household lamps are filled with argon gas, and a bit of nitrogen. I suppose it helps cool the fulfillment, but don't know for sure. Dry air would be no good, as it contains oxygen.


As for 3000 degrees K for white, it's "warm white" in common parlance. 3200K is typical white for hot lights, 5000K or 5500K for daylight balanced lights and flash. Video white point is usually said to be 6500K.

(I'm the son of a lighting designer, now in the video biz, so keep all this trivia in my head).

[tvrgeek]

"Dry air would be no good, as it contains oxygen. "

EXACTLY, which is why 40W bulbs burn out so fast, as do discount ones.

The trick with the inert gas is it helps to re-deposit the out-gassed tungsten back on the filament, not the envelope. They call them "halogen" bulbs.

I am only going by the GE manual. I had a lot of time to kill while babysitting a PDP-8 doing all my work for me.

[Pano]

That's certainly not my understanding. If the bulb had air in it, the filament would burn up in a jiffy. Vacuum is preferred for small envelopes. In typical 40W-200W household bulbs, Argon is used as the inert gas. Halogen lamps are another class, as they have added halogen gas for the halogen cycle. The re-deposit of the tungsten on the filament allows a higher temp filament which would otherwise have a very sort life. FWIW, you can now get halogen lamps inside the typical 60W-100W pear shaped bulb. Those are legal under the new energy rules.

But I'm an end users, not a manufacturer, so my be a bit dim in my knowledge.

[jitter]

Originally Posted by AndrewT

It seems much of the bad press and bad reputation for the "new" is down to excessive claims by the proponents.

If we do our research the truth is out there.

And that is exactly why in the EU it is mandatory nowadays that packages clearly show some relevant data, such as lumen output, average lifetime, warm up time to 60% light output, etc. In the attachment there are two different CFLs, but the same data is to be found on (halogen) incandescent and LED bulbs as well.

The misuse of equivelent incandescent wattage is what probably led to this info becoming mandatory. As you can see it is still allowed, but must be printed in a smaller size than the actual lumen output, and must not be rounded up. In the past a 600 lm CFL was said to be equivalent to a 60 W bulb by the manufacturers, but frosted 60 W incandescents actually did slightly over 700 lm.
I was given a LED bulb a couple of years ago that claimed to be a replacement for "up to 60 W" bulbs. With only 300 lm output, that clearly wasn't true.

Luckily this no longer happens as a result of these regulations.

[freax]

Originally Posted by jitter

Luckily this no longer happens as a result of these regulations.

Oh man, those Tornado models put out a lot of light though, i've got 3x of the 18 watt variants, and boy does it light up the shed!

Especially when using a plastic reflector, which should last forever too.

its pretty harsh though the light, which is why sometimes during offpeak hour I turn on the 3x 100 watt halogen lamps, which I did have running off a dimmer but then I thought to myself, hey if this bulb isn't getting hot enough doesn't that mean that the halogen recouperation process won't work, so I ended up not using the dimmer anymore.

Halogen to me gives off the nicest light, if its properly UV shielded, otherwise it dries out my skin then. But Halogen can't be dimmed either I thought.

So its back to the good old 60w-100w incandescent globes for me.