LED Stage Lighting

A rock concert yesterday made me ponder on some of the differences between the old and the new ways of lighting a stage.

For some inexplicable reason, modern stage lighting seems not so much focused on illuminating the actual performers as on flashing harmfully bright and narrow coloured beams or flashes into the eyes of the unsuspecting audience at irregular intervals during the concert. How this practice can be even legal is probably a matter of ignorance on the part of lighting technicians and regulating authorities. Sometimes real laser beams are used.


The new LED technology has both advantages and disadvantages.

+ LED uses less energy (if power factor is good) and lasts much longer (if drivers are of good quality and don’t get overheated).

+ LED floodlight does not emit heat in the beam direction as incandescent light does, so performers will not overheated from the lighting.

+ LED diodes are small and versatile and can be used for more creative effects if so desired (as exemplified at the London Olympics).

+ LED diodes are already coloured and directional and do not require coloured filters.

– LED light is much sharper and more laser-like than incandescent light. It’s a sort of digital light that is either on or off, with no softly glowing tungsten filament to ease the transition. It thereby lacks some of the charm of older types of stage lighting and gives a more high-tech effect that is less flattering to performers and much harder on the eyes.

– Cool white light it is horridly harsh, unflattering and a real mood-killer, compared to the warm sunny glow of traditional tungsten light.

– Blue, green and cool-white LED light can damage the retina if bright and beamed directly into the eyes.

My recommendation to stage lighting technicians:

• Rethink the practice of lighting up the audience at all. People come to watch the show, not to be illuminated themselves. Therefore lighting should be directed towards the stage, not be placed at the stage and directed at the audience. If lighting effects on or around the stage are desired, they should be only be decorative (e.g. non-directional, low-lumen dots or panes) and not illuminating.

• Avoid cool white light. Complement the coloured LEDs with halogen floodlights if you want performers to look good on stage. Just a few won’t add that much heat.

• Use blue light sparingly and don’t direct it into people’s eyes.

• Don’t use lasers. If you have to, don’t direct them at any living being.

• Don’t use strobe lights as this can cause epilepsy in susceptible people and is generally irritating.

For the audience I recommend bringing sunglasses as well as ear plugs in order to avoid eye damage until lighting designers have learned how the new technology can be used safely.

Good article about stage lighting with LED:

LED Stage Lighting – Why Buy RGB LED Stage Lights?


LED Update

Over the last couple of years there has been a very rapid development of LEDs. Some problems still remain, others have been mitigated in innovative ways. Summary from some of the latest studies, reviews and consumer tests (links below):

1. Prices have gone down, from shockingly overpriced to reasonably affordable (≈ 4-40€) (1, 2, 3).

2. Brightness. More higher lumen models (600-800 lm have been introduced, and even a few 1100+ lm), but most LEDs are still low-lumen  (≈ 400 lm) – which make the least economic and environmental sense to replace and make dimmable.

3. Efficacy (lumen/watt) has improved (≈ 80 to 96 lm/w). (My comment: But as always, only if not including poor power factor and heat replacement effect in colder regions.) Both watts and efficacy were found to be overstated in many of the lamps tested, sometimes understated. Usually just by a few per cent, but some lamps gave up to 39% less light than claimed on the box (1, 2, 3).

4. Colour rendering index has technically improved (CRI over 80 for most LEDs, a few even over 90). This, however, does not mean that the spectral power distribution is as even or full-spectrum as incandescent and sunlight, only that it has been tweaked to reproduce the required 8 colour samples more accurately when testing.

5. Light colour has improved for many warm-white LEDs. Only a few years ago most LEDs were a ghastly cool-white and the few marketed as “warm-white” could be anything from yellow, orange, greenish, blueish, or pinkish to a dull grey-white. Now, many LEDs have reached a similar decently warm-white emulation as CFLs finally did after 20 years, but the light colour may still vary between models and correlated colour temperature is often somewhat colder than the stated 2700K, according to the latest Swedish consumer tests (2, 3).

6. Colour consistency over time seems to have improved. A multilateral (pro-LED) European study found that only a few lamps exceeded the 6 MacAdam step tolerance limits after 100 and 1 000 h testing (1).

7. Power Factor can still be a problem and may vary greatly between different brands and models – without obvious connection to price. In the last U.S. DoE tests 2011  PF varied from 0.58-0.98 (6). The 2015 European study found all tested samples “to comply with EU requirements” (1). (But the EU requirements for home LED lamps under 25 W is only 0.5 – which means that those with poor PF may still use up to twice their rated energy!)

8. Dimmability. More LEDs are dimmable – but many are still not compatible with all dimmers, so read the specifications carefully. Some of the dimmable samples tested by Testfakta started humming, flickering or shut off completely when dimmed (2). The European study found similar problems (1).

“Five of the LED lamps purchased for this study were marketed as ‘dimmable’. Of these, two of those lamps were able to be dimmed on both types of dimmers (#6 IKEA, #13 Star Trading). The other three lamps had issues with one of the dimmers. Lamp #5 from LED Connection was not compatible with the leading edge dimmer and Lamps #14 from OSRAM and #15 from Philips were not compatible with the trailing edge dimmer.”

9. Warm-dim LEDs. A new generation of LEDs which turn warmer when dimmed have been introduced, thereby better mimicking natural filament lamps – one of the complaints of earlier LEDs and CFLs. These are more expensive, of course (≈ 15-20 €.) (Will test and post review later.) From the Osram press-release:

“In the evenings, and especially when evenings become longer, many people love the snug, warm glow of a burning candle or open fire. Incandescent and halogen lamps create similarly cozy light by simple dimming, but with modern LED lamps this is technically not quite as simple. To create the popular light effect with 2,000 Kelvin here as well, Osram has integrated state-of-the-art LED technology into its new Glow-Dim models.”

(My comment: Funny that that warm romantic glow, priced by so many, was completely ignored by the lighting industry and legislators both, when it was produced by incandescent lamps. But now that there is a synthetic, heavily overpriced, replacement this quality is used to sell a fake copy of the real thing which we all used to love.)

Osram Glow-Dim
Philips Warm Glow
Airam Dim-to-warm

10. Flicker can still be a problem in some lamps. Last summer Hillevi Hemphälä at the Lund Technical Institute started testing LEDs for flicker. She says it’s hard to for the consumer to know which lamps are good or not, as this is not always reflected in the price. There are LEDs powered by a pulsed current, which is a cheaper construction and facilitates dimming, but it can also increase subliminal flicker.  “Problem med flimmer från LED-lampor” Final test results are yet to be published. Testfakta found the flicker index to vary between 0.01 (virtually no flicker) to 0.11 – but no correlation with the price (2). The multilateral European study said, “The flicker index and percent flicker of the lamps were measured and many lamps had no flicker” (1) – which is a roundabout way of saying that the rest of the lamps did have flicker.

11. Life span appears more reliable than for CFLs. LEDs don’t seem to be sensitive to rapid switching on/off, only to overheating which may make some LEDs expire prematurely.

2014, customers were not so impressed (4):

“We lit up your frustrations when we last spoke about LED light bulbs. More than 300 comments were made, most of them about their poor performance and your dissatisfaction with them not living up to their lifespan claims.”

“We’ve tested 410 LED light bulb samples for 10,000 hours or more, and 75 of those (18%) failed within 10,000 hours, even though they all claim to last much longer. And 69 out of the 185 bulbs (37%) we examined at the 15,000 hour mark had failed by that point. Again, almost all of them claim to last longer than this. So, although there are advances, there’s still room for improvement.”

Swedish consumer test magazine Råd&Rön says all their earlier tested LEDs have lasted longer than 5 000 hours so they discontinued durability tests for LEDs, as the models involved would be replaced in the market by the time the long-term test was done (3).

Philips famous L-prize LED has now passed 40 000 hours with no failures and 93.7- 97.5% lumen maintenance, which is very good compared with CFLs (5). (Its 70€ European cousin is still burning nicely in my outdoor luminaire after 3.5 years.)

In the European study, a few LEDs were non-functional right out of the box ().

“Three of the 170 LED lamps tested were defective and did not operate out of the box (and thus could have been returned for a refund / replacement) – thus these lamps were not used in our testing and those models simply had smaller test samples studied. Two individual LED lamps sold by ccLED (both sample #11) failed during the burn-in. Lamp #12 had one unit fail during measurements, but all the other LED lamps so far have not have problems after 1000 hours of testing.”

12. Light distribution has improved. Spreading the light equally in all directions has been a challenge as diodes are naturally directional with quite a narrow beam angle. To get around that problem, diodes were first just placed around a central stick – with mediocre results. Some brands have now solved this by adding a diffusing lens over a single power-LED die – which also markedly increases the price but gives a light distribution more like that of a traditional bulb (though never with the same sparkling clarity, sunny feeling, or beautiful glow, of course).

LED A prism, Osram (lysman.com)

13. Filament LEDs. A new type of filament LED has also been introduced, both to give a better 360° light, and to replace the old Edison-type decorative carbon filament bulbs (which is probably why the EU commission is now removing the exception for those in the latest Directive amendment). It consists of tiny diodes packed closely together on 2 to 8 filaments inside the bulb. This also reduces internal heat and the need for a heavy and cumbersome heat sink, so this type of lamp can be made neater, more light-weight and closer to the original incandescent bulb. (Again, interesting how so much effort is put into trying to emulate all the quality and design advantages of the banned bulb if it was so bad.) 

LED Filament 2200K (E27)

I tested a filament LED with CRI 90 (= improved colour rendition) from Star Trading.  For me it was still not close enough to want to replace a real incandescent bulb in my living room, but OK for outdoors. Others might find it acceptable.

LED decorative c

Filament LED

14. Temperature-tolerance. LED lamps are ideal for outdoors, even in the winter, as they are not sensitive to cold like CFLs (which can take forever to light up in cold temperatures). Outdoor lamps are also the most worthwhile replacing if left on for many hours per day, or night. However, LEDs are still sensitive to heat and cannot be used for example in a sauna. Only incandescent/halogen lamps tolerate heat well.

15. Health risks risks may still be an issue. This LEDs Magazine summary is from 2010 but LED light has not changed substantially, other than glare often being less of an issue than with early lamps. But they still contain more blue light which can irritate the eye, disrupt circadian rhythm and be harmful to people with blue-light sensitive eye conditions. Flicker can also be disrupting (and for epileptics even dangerous). Others experience a various symptoms, e.g. migraines, vertigo, nausea, inexplicable visual distortions that make it impossible to see in LED lighting and much more. An anecdotal example sent to Incandescent Anna:

“I am extremely sensitive to LED lighting both indoor and outdoor. They have been erected outside my home and now I can’t even step in to my own front garden without symptoms of severe eye pain, migraine, nausea, vomiting, aura, vertigo, increased heart rate and ringing in my ears. It hits me immediately and the severity and length of symptoms depend on the length of time I’m exposed. 
I have known for 7 or 8 years of this extreme intolerance to LED when I first got a DS Lite, back-lit with LED and I couldn’t bare to look at it. I can’t use any LED backlit phones or monitors. I don’t think that my symptoms are getting worse but my recovery period is now non existent because LED is everywhere. If I am round CFL for a prolonged period I develop headache and agitation but nothing like the symptoms I have around LED.”

16. LED li-fi. LED lamps can now be used for delivering ultra fast wi-fi. Considering how many have experienced severe symptoms from smart meters, does this sound like a good idea?

Tests & Reviews

1. Test Report – Clear, Non-Directional LED Lamps (Swedish Energy Agency, Belgian government, CLASP’s European Programme, eceee, 2014-2015)
eceee – summary of above test
2.Testfakta – test table (Sweden 2015, partly in English)
“LED närmar sig glödlampans ljuskvalitet” (test article in Swedish)
3. Råd & Rön – LED test (Sweden, 2015-2016, 25 SEK to read)
4.“A Nobel Prize for LED bulbs but do they get your vote?” (UK, Oct 2014)
5. “DOE Testing of L Prize LED lamp passes 40 000 hours” (USA, Aug 2015)
6. U.S. DoE – CALiPER SSL tests (USA, 2007-2016, detailed but not very updated)
Stiftung Warentest – Lampen im Test Das beste Licht für Sie (Germany, 2015, 3€)
Consumentengids – Test Ledlampen.pdf (Netherlands, 2015)
CNet – Best LED Light Bulbs (2016)
Best LED Light Bulb Reviews and Comparisons

Flickering LED

A friend’s ​apartment building has recently been refurbished with warm white LED downlights in the entrance hall and corridors. Being of higher quality than the usual mediocre LED bulbs sold in shops, these lamps gave a more pleasant light and ambiance than the tired old fluorescent tubes. The change also included motion sensors which would turn the lights off when not in use, which is smart and energy saving. All in all, a definite upgrade.

However, last time I went to visit, one of the downlights had gone completely crazy and flickered in regular bursts like a strobe light! Even though I’m not prone to seizures, I found it extremely disturbing and could hardly walk past it with my eyes open. After making sure the super would come and fix it a s a p, I managed to film a few seconds of this horror. (Do NOT watch if you’re epileptic!)

I don’t know if this is common behaviour in failing LEDs. These were less than a year old and should not be failing so soon. Oh, and it turned out the super couldn’t do anything as these LED downlights required specialist help from the company that installed them. No longer a matter of just replacing a burned-out bulb or tube.

Even though annoying enough, I’ve never seen a failing fluorescent tube flicker with such a sharp and piercing strobe effect. This seems like a rather serious issue.

For instance, photosensitive epilepsy is more common than one might think, affecting “about one in 4000 individuals,” according to the group. Factors that may combine to affect the likelihood of seizures include flash frequency in the range of 3 to 65 Hz, and especially in the range from 15 to 20 Hz. That’s why line frequency fundamentals (50 or 60 Hz, depending on country) are important and why asymmetric behavior of the external triac controller is significant.”

More to read on LED flicker:


Update: The year after, another LED downlight in that same apartment building started flickering in exactly the same way. It kept doing so for weeks before it got fixed.

Blue Light Hazard?

The blue light issue has several aspects. First one needs to separate between the tiny bright blue diods used on some electronic devices, the blue-white light from white LEDs, CFLs and xenon arc car headlight lamps, and the (more or less) warm-white light from incandescent-mimicking CFL and LED.

This blog is primarily about replacement lamps for general illumination, not signal lights, monitor backlighting and the like, but the information on bright blue light may still be relevant for the cool-white light as well.

Blue light

Let’s start with the bright blue lamps. From the Wikipedia LED page:

Blue hazard: There is a concern that blue LEDs and cool-white LEDs are now capable of exceeding safe limits of the so-called blue-light hazard as defined in eye safety specifications such as ANSI/IESNA RP-27.1–05: Recommended Practice for Photobiological Safety for Lamp and Lamp Systems.

This web article Blue LEDs: A health hazard? explains the problems with bright blue light in detail:

Blue appears brighter at night

Firstly, blue light appears much brighter to us at night, or indoors where ambient light is low – an effect known as the Purkinje shift. This is because the rods – the sensitive monochromatic rod light detectors which our retinas rely on more at night – are most sensitive to greenish-blue light. (Some hypothesize that animals evolved the rods in underwater and jungle environments, hence the bias to blue or green – later we developed separate full color vision on top of that system, but the sensitive rods remained).

A practical example of the Purkinje Shift: a cool blue power LED on a TV might catch your eye and even attract you to buy it in a well-lit store. But after you take it home, the same LED appears distractingly bright when you watch the TV in a darkened room.

And blue is brighter in peripheral vision

The Purkinje shift also noticeably brightens blue or green lights in our peripheral vision under medium to low light conditions, because there are comparatively more rods towards the edge of the retina – hence complaints that blue LEDs are distracting even when they’re not the focus of attention.

“Glaring LEDs on displays that you need to see at night… that’s poor design,” says Brandon Eash. Remarkably though, it is a mistake that manufacturers continue to make.

Blue does not help you see clearly

We tend to associate blue with coolness, accuracy and clarity. But paradoxically, our eyes cannot focus blue sharply. We actually see a distracting halo around bright blue lights.

“It’s well recognized that blue light is not as sharply focused on the retina as the longer wavelengths. It tends to be focused in front of the retina, so it’s a little out of focus,” explains Dr. David Sliney, a US Army expert on the physiological effects of LEDs, lasers, and other bright light sources.

The various wavelengths of light focus differently because they refract at slightly different angles as they pass through the lens of the eye – an effect known as chromatic aberration.

For similar reasons, blue scatters more widely inside the eyeball, says Dr. Sliney, who answered questions by phone last year from his office at the US Army Center for Health Promotion and Preventive Medicine in Maryland.

We’re half blind in blue

The modern human eye evolved to see fine detail primarily with green or red light. In fact, because we are poor at distinguishing sharp detail in blue, our eyes don’t really try. The most sensitive spot on the retina, the fovea centralis, has no blue light-detecting cones. That’s right: we’re all color blind in the most sensitive part of our eyes.

In addition, the central area of the retina, the macula, actually filters out some blue light in an effort to sharpen our vision. Snipers and marksmen sometimes improve on nature by wearing yellow-tinted ‘shooters glasses’, which block the distracting blue light.

“You throw away a little bit of color information in order to have a sharper view of things,” explains Dr. Sliney.

Blue glare interferes with vision

The twin effects of fuzzy focus and blue scatter both make intense blue light from a point source, like an LED, spread out across the retina, obscuring a much wider part of our visual field.

Although our retinas simply don’t handle blue very well, nobody told the rest of the eye that. If blue is the strongest color available and we want to see fine detail, then we strain our eye muscles and squint trying to pull the blue into shaper focus. Try to do this for too long and you’ll probably develop a nauseating headache. This won’t happen in a normally lit scene, because the other colors provide the sharp detail we naturally desire.

A dazzling pain in the eye

By the way, the physical pain some people feel from high intensity discharge (HID) car headlights and particularly intense blue LEDs seems to be a combination of these focus and scatter effects, together with a third. We have a particularly strong aversion reaction to bright blue light sources, including bluish-white light. “Pupilary reflex is down in the blue [part of the spectrum]. The strongest signal to the muscles in the iris to close down comes from the blue,” says Dr. Sliney.

Intense blue light can cause long-term photochemical damage to the retina. Now, nobody is claiming that you’re likely to suffer this kind of injury from a normal blue LED (unless you stare fixedly at it from a few millimetres for an hour). However, it is theorized that this may be the evolutionary driving force behind the immediate feeling of pain we get from bright light with a very strong blue component.

Our body’s instinctive reaction is to reduce blue light entering the eye by closing down the pupil. This means that blue light spoils night vision. After a brief flash of blue, you can’t see other colors so well for a while.

White light

When it comes to lamps for general illumination, the issue gets more complex. Cool-white or daylight-mimicking indoor illumination may not be as good for vision as previously assumed. But can it be harmful?

CELMA-ELC-GLA (lighting industry):

In June, PLDA Greenpages blog reported on new studies that “have concluded that LEDs present no greater optical hazard than other common artificial lighting sources”. The link required business and registration to be accessed, but the abstract appears to be the same as in this March 2012 white paper of the Global Lighting Association on The Optical & Photobiological Effects of LED, CFLs and Other High Efficiency General Lighting Sources, which in turn appears to be fairly identical to the July 2011 position statement from CELMA and ELC (European luminare and lamp manufacturers, respectively): Optical safety of LED lighting.

If it is the same document, I wouldn’t exactly call it a study as it only gives technical explanations of why LEDs and CFLs belong to risk groups 0 or 1, which may be correct, but cites no studies on actual health effects; it’s all just extrapolation of their own data. Quoting some relevant parts of the document (not all in original order):

Potential effects on the eye
Commonly discussed hazards affecting the eye are blue light hazard (BLH) and age‐related macular degeneration (AMD) which can be induced or aggravated by high intensity blue light. Furthermore, UV (ultraviolet) may affect the eye, causing cataract or photokeratitis (sunburn of the cornea); IR (infrared) radiation can induce IR cataract (also known as glassblower’s cataract); and, radiation of all wavelengths can lead to retinal thermal injuries at extreme intensities.

Potential effects on the skin
Optical radiation, particularly UV can be harmful to the skin. By far the most hazardous source to consider is the sun. Sunburns (UV erythema) and skin cancers due to long‐term exposure to the sun are well‐known problems caused by radiation. Moreover, patients with autoimmune diseases such as lupus or photodermatoses can be highly sensitive to UV radiation, and sometimes also blue light. There is concern among some patients who suffer from such sensitivities that phasing out of the known incandescent lamps will leave them without lamps for indoor use that are low in radiation of UV and blue light. 

4.1 Conclusions on blue light emission
Evaluation at a distance producing 500 Lux: Taking the 500 Lux criterion as the measurement basis, none of the LED products belongs to risk group 2. This was also confirmed by a study of the French agency for food, environmental and occupational health & safety (ANSES) in 2010 which found that even high‐output discrete LEDs are classified into risk groups 0 or 1 if the 500 Lux criterion is applied.

Precautionary measures with regard to children
The lens of a child’s eye filters blue light less efficiently than an adult’s lens. Children are thus more sensitive to blue light hazard. Therefore, at places frequented by children particular care must be taken to ensure that lamps and luminaires are chosen and installed in such a way as to avoid people looking directly into the light source. It is not necessary that LEDs (or blue light in general) are avoided in an environment with children present, for the reasons stated above. If used across a broad surface or area, in a way which does not produce glare, even “pure” blue light is completely harmless; regardless of whether it is the blue in daylight or produced by LEDs or other light sources.

Guidance for people with high sensitivity for blue light
The above statements are valid for healthy people in the general public. People with highly sensitive skin or eyes for blue light may be wise to investigate alternative light sources that operate on a more specific radiation band not covered by the applied action curves that cover a broad range of radiations. The comparative data given in the annexes of this paper serve to give guidance in selecting the best available type of light source for a given sensitivity.

The biological importance of blue light
It needs to be mentioned that blue light exposure is important to human beings. Blue light with a peak around 460‐480nm regulates the biological clock, alertness and metabolic processes. CELMA‐ELC has installed a special working group to translate these findings into practical application norms and standards. In natural conditions, outdoor daylight fulfils this function. Yet, people spend most of the day indoors (offices etc.) and are often lacking the necessary blue light exposure. Blue and cool white light sources can be used to create lighting conditions such that people will receive their daily portion of blue light to keep their physiology in tune with the natural day‐night rhythm. Due to the highly flexible application possibilities, LED based light sources are particularly well suited for that purpose. 

Annex 3: Blue light radiation data of light sources
When evaluating the risk of blue light hazard posed by LED (and other) light sources, two fundamentally different cases need to be considered:

Case A: Looking at an illuminated scene
[…] Case A can generally be considered safe. To give an example, looking at the scattered blue sky (high blue irradiance but low radiance) is completely safe, and so are artificial light sources, containing way less blue irradiance than daylight.

Case B: Looking at a light source
[…] Looking straight at a light source (case B) is also in general safe for diffuse and warm white light sources, like frosted or white diffusing lamps. Yet, caution is advisable for cool white or blue, bright (high intensity), point‐like light source, for instance an incandescent filament, electric arc or an LED die, even an LED die behind the lens of a directional lamp.  Such point‐like sources are projected on the retina as a concentrated light spot and can damage that spot on the retina when the intensity is high enough and the spectrum contains blue light in congruence with the blue light hazard action spectrum curve.

4.2 Conclusions on ultraviolet radiation (UV) 
LED based light sources do not emit any UV radiation (unless specifically designed for that particular purpose). Therefore, they are not harmful to people with a specific sensitivity for certain UV radiation and can bring relief to certain groups of patients. In this respect, LED based light sources provide advantages over traditional incandescent, halogen and Compact Fluorescent lamps. For more details see Annex 2.

4.3 Conclusions on infrared radiation (IR)
In contrast to most other light sources, e.g. halogen and incandescent lamps, LEDs hardly emit IR light (unless specifically designed to emit a certain type of IR). For available types of indoor light sources the IR radiation is not powerful enough to pose any risks to human.

To summarize the key findings, LED sources (lamps or systems) and luminaires are safe to the consumer when used as intended.

Which is: Don’t sit too close to a UV-emitting light source. Don’t look straight into cool-white or bright light sources (risk increases with proximity, brightness and time). Always use low-voltage halogen mini bulbs and halogen mini tubes on luminaires with glass cover (regular glass filters out the UVC which the quartz glass lets through). Use warm-white LED, CFL or halogen in frosted outer bulb if UV-sensitive.

In terms of their level of photo biological safety, LED lamps are no different from traditional technologies such as incandescent lamps and fluorescent tubes. The portion of blue in LED is not different from the portion of blue in lamps using other technologies at the same colour temperature.

The last sentence seems a bit tautologous as otherwise it would not have the same colour temperature. How the blue portion can be “the same” for same colour temperature LED and incandescent despite their different spectral power distribution is given an explanation:

White LEDs typically show a peak in the blue (at around 450 nm when a royal blue LED is used) and more broadband emission in the green/yellow part of the spectrum. Next to the blue peak, a dip is visible at around 490nm that also falls under the BLH action curve (…). The blue peak of the LED lamps is “compensated” by the dip, therefore the total blue output (…) of LED of 2700K is comparable to an incandescent lamp of 2700K.

This still does not make the spectrum exactly the same, even if the net result is a similar blueness. And most LEDs available on the home market is very much bluer than the 2700 K of the very best (and most unaffordable) warm-white LEDs. 

Nevertheless, looking straight into bright, point‐like sources (LEDs, but also other strong point‐like light sources, like clear filament or discharge lamps and including the sun) should be prevented. However, when people happen to look into a bright light source accidentally, a natural protective reflex occurs (people instinctively close their eyes or look away from the source).

True enough.

A comparison of LED retrofit products to the traditional products they are intended to replace reveals that the risk levels are very similar and well within the uncritical range.

But that was for the 6 watt warm-white LED in a frosted outer bulb included in the comparison. White 4000 K LEDs and directional high power LEDs, as well as other bright point light sources, including clear tungsten filament lamps, fall into risk group 1.

The bar chart included in the document shows that the higher the CCT, the higher the blue light hazard, regardless of light source (as would be expected);

(Two other bar charts (fig. 5 & 6) quite strangely compared frosted warm-white LED lamps with clear incandescent lamps, in order to make incandescent light appear to to have more blue light, rather than to compare it with the other point-like sources. In those charts, the frosted incandescent lamp seemed to be the safest.)


In 2011, the European Commissions Scientific Committee on Emerging and Newly Identified Health Risks (one of the independent scientific committees of the European Commission, which provide scientific advice to the Commission on consumer products) issued an updated report on Health Effects of Artificial Light which seems partly based on the information given by European Lamp Companies Federation, ELC (extracts, emphases added):


A: Potential health impacts on the general public caused by artificial light

In general, the probability is low that artificial lighting for visibility purposes induces acute pathologic conditions, since expected exposure levels are much lower than those at which effects normally occur, and are also much lower than typical daylight exposures. Certain lamp types (quartz halogen lamps, single- and double-capped fluorescent lamps as well as incandescent light bulbs) may emit UV radiation, although at low levels. However, according to a worst case scenario the highest measured UV emissions from lamps used typically in offices and schools [usually fluorescent tubes] could add to the number of squamous cell carcinomas in the EU population.

Household lighting involves an illumination level which is so low that exposure to potentially problematic radiation is considered negligible. There is no consistent evidence that long-term exposure to sunlight (specifically the blue component) may contribute to age-related macular degeneration (AMD). Whether exposure from artificial light could have effects related to AMD is uncertain.

No evidence was found indicating that blue light from artificial lighting belonging to Risk Group 0 (“exempt from risk”) would have any impact on the retina graver than that of sunlight. Blue light from improperly used lamps belonging to Risk Groups 1, 2, or 3 could, in principle, induce photochemical retinal damage in certain circumstances. There is however no evidence about the extent to which this is actually occurring in practical situations.

There is mounting evidence suggesting that ill-timed exposure to light (light-at-night) may be associated with an increased risk of breast cancer, and can also cause sleep disorders, gastrointestinal, and cardiovascular disorders, and possibly affective states. Importantly, these effects are directly or indirectly due to light itself, without any specific correlation to a given lighting technology.

But bluer light (such as from cool-white or daylight LEDs and CFLs) has a greater effect on melatonin, even at very low intensities if used at night (see Circadian Rhythms below).

B: Aggravation of the symptoms of pathological condition

The SCENIHR opinion on Light Sensitivity identified that some pre-existing conditions (epilepsy, migraine, retinal diseases, chronic actinic dermatitis, and solar urticaria) could be exacerbated by flicker and/or UV/blue light. At that time there was no reliable evidence to suggest that compact fluorescent lamps (CFLs) could be a significant contributor. More recent studies indicate a negative role for certain CFLs and other artificial light sources (sometimes including incandescent bulbs) in photosensitive disease activity.

UV, and in some patients, visible light can induce skin lesions of true photodermatoses. Although sunlight is reported by most patients as the main source of disease activity, artificial lighting is reported to play a role in some cases. The blue or UV components of light tend to be more effective than red components in aggravating skin disease symptoms related to pre-existing conditions such as lupus erythematosus, chronic actinic dermatitis and solar urticaria. UV and/or blue light could also possibly aggravate the systemic form of lupus erythematosus. It is recommended that all patients with retinal dystrophy should be protected from light by wearing special protective eyeware that filters the shorter and intermediate wavelengths.

3.3.3. Lamp emissions

Based on emissions from the lamp, the Standard EN 62471 (and also IEC 62471 and CIE S009, since they are all identical in this sense) categorizes the lamps according to the photo-biological hazard that they might pose. The different hazards are:

1. Actinic UV-hazard for eye and skin (see section;
2. UVA-hazard for the eye (section;
3. Blue-light hazard for the retina (section;
4. Thermal retina hazard (section and
5. IR-hazard for the eye (sections and

According to the standards, measurements should be performed according to two approaches; viz. at a distance where a light intensity of 500 lx is obtained and also at a distance of 20 cm (…). Based on these measurements, lamps are then classified according to the “Risk Group” (RG) to which they belong. RG0 (exempt from risk) and RG1 (minor risk) lamps do not pose any hazards during normal circumstances. RG2 (medium risk) lamps also do not pose hazards because of our aversion responses to very bright light sources, or due to the fact that we would experience thermal discomfort. RG3 (high risk) include only lamps where a short-term exposure poses a hazard. This classification is based on acute exposure responses (a single day, up to 8 hours) and applies only to individuals of normal sensitivity.

The contribution from the European Lamp Companies Federation (ELC) included six lamp types from eight manufacturers, considered by ELC to be “representative lamp types”. Assessment of effects on the healthy eye


Discomfort glare does not impair visibility but causes an uncomfortable sensation that causes the observer to look away from the glaring source. It increases when the light source is facing the observer.

Disability glare is due to the light scattering within the ocular media which creates a veil that lowers any contrast and renders viewing impossible.

The luminance of the sky is rather stable at about 5,000 cd/m2. This value can be exceeded on bright surfaces on clear days when luminance can reach several tens of thousands cd/m2. The sun is never viewed directly except when it is at sunrise or at sunset when its luminance is about the same as the sky and its colour temperature low or moderate. 

It is when both the luminance and the colour temperature of the light are high that the blue light hazard increases.

The UV/blue light risk on the healthy majority is considered by ELC to be very low and SCENIHR accepts this, but with some questions regarding high power LEDs, wrong use and “non-representative lamps” (= lamps other than the “representative lamps” submitted to SCENIHR by the ELC):

The results presented in the ELC report suggest to SCENIHR that there is little or no risk to individuals of normal sensitivity from the UV, IR or blue light optical radiation emission from lamps which are considered to be “representative” of the type of lamps selected to replace incandescent lamps. SCENIHR however considers that “non-representative” lamps may emit levels that are much higher than those included in the report; however quality control limits applied by lamp manufacturers were not reported. Further consideration should also be given to the “intended” vs. “reasonable foreseeable” use of lamps. Further consideration also needs to be given to the risk classification of high power LEDs. Also, halogen lamps that are intended to be used with an external glass filter must not be used without the filter because of the risk of exposure to UV radiation. Circadian rhythms

Recent studies indicate that ill-timed exposures to even low levels of light in house-hold settings may be sufficient for circadian disruptions in humans.

A comparison between the effects of living room light (less than 200 lx) and dim light (<3 lx) before bedtime showed that exposure to room light suppressed melatonin levels and shortened the duration of melatonin production in healthy volunteers (18-30 years) (Gooley et al. 2011).

Cajochen et al. (2011) compared the effects of a white LED-backlit screen with more than twice the level of blue light (462 nm) emission to a non-LED screen on male volunteers. Exposure to the LED-screen significantly lowered evening melatonin levels and suppressed sleepiness.

In another study from the same group (Chellappa et al. 2011) 16 healthy male volunteers were exposed to cold white CFLs (40 lx at 6,500 K) and incandescent lamps (40 lx at 3,000 K) for two hours in the evening. The melatonin suppression was significantly greater after exposure to the 6,500 K light, suggesting that our circadian system is especially sensitive to blue light even at low light levels (40 lx)

However, no study has investigated whether the impact of warm white CFLs and LEDs (2,700-3,000 K) on melatonin suppression is in any way different from that of incandescent lamps.


There is a moderate overall weight of evidence that ill-timed exposure to light (light-at-night), possibly through circadian disruption, may increase the risk of breast cancer. 

There is furthermore moderate overall weight of evidence that exposure to light-at-night, possibly through circadian disruption, is associated with sleep disorders, gastrointestinal and cardiovascular disorders, and with affective disorders

The overall evidence for other diseases is weak due to the lack of epidemiological studies.

It seems that bright white light in the daytime can be helpful in keeping one alert for work (though preferably the real thing rather than a daylight-mimicking copy). But at night – very bad idea! Unless you’re doing shift work and really need to stay awake.

I have started noticing the effect of bright white light at night. My macbook has a LED screen and the cool-white background on most pages tends to be a very bright. Great in the daytime, not so great at night… So I’ve installed the f.lux app that adjusts the screen light temperature to follow the sunset at one’s particular location, and a similar app for my OLED screen Android.

I also try and make sure to get enough real daylight in the daytime and then I dim indoor lights more and more as the evening progresses. With these simple measures, my very easily disrupted circadian rhythm has gotten markedly more normal, almost miraculously so.

ANSES (France):

The French Agency for Food, Environmental and Occupational Health Safety have issued official warnings about selling white LED lamps to the general public due to the toxic effect of blue light.

The principal characteristic of diodes sold for lighting purposes is the high proportion of blue in the white light emitted and their very high luminance (“brightness”). The issues of most concern identified by the Agency concern the eye due to the toxic effect of blue light and the risk of glare.

The blue light necessary to obtain white LEDs causes toxic stress to the retina. Children are particularly sensitive to this risk, as their crystalline lens is still developing and is unable to filter the light efficiently.

These new lighting systems can produce “intensities of light” up to 1000 times higher than traditional lighting systems, thus creating a risk of glare. The strongly directed light they produce, as well as the quality of the light emitted, can also cause visual discomfort.

Blue pollution

From the Wikipedia LED page:

Blue pollution: Because cool-white LEDs with high color temperature emit proportionally more blue light than conventional outdoor light sources such as high-pressure sodium vapor lamps, the strong wavelength dependence of Rayleigh scattering means that cool-white LEDs can cause more light pollution than other light sources. The International Dark-Sky Association discourages using white light sources with correlated color temperature above 3,000 K.

So, no cool-white LED or metal halide streetlights please!

More on LED

Light Colour

I recently had a look at some of the currently available LED bulbs in my local hardware store. The majority were more or less appalling in light colour. Two clear bulbs (with little light dots stuck on a stick) were green-white. Seven of the frosted LED bulbs were an odd sort of cool purple-blue-white despite being marked as “warm-white”. Only a few were even remotely warm-white for real. Many of the LED bulbs were also very dim, and useful for absolutely nothing.

But I have to say that the 12 W Philips Master LED-series MyAmbiance bulb (Swedish consumer test winner 2011 and predecessor of the improved U.S. L-Prize test winner) looked very incandescent-like from just looking at the lit bulb there in the store, and it was nice and bright without being glaring.

But as I didn’t feel like spending €70 (!) on a lamp I’m not sure I’ll like at home, or how long it will last or retain its original colour and brightness, I have yet to see how it looks in a home environment without all the lit surrounding lights. Maybe I’ll buy one later anyway just to satisfy my curiosity.

It was very heavy though… Probably because of all the electronics inside and the amount of metal needed for heat sink.

Philips online catalogue specifies it as Warm White, CCT 2700K, CRI 80, approx 825 Lm, and 25 000 hr rated average life.

Left: an unlit Philips 12 W Master LED
Right: a lit Philips 10 W L-Prize winner
Source: youtube screenshot

As can be seen in the latest CALiPER test by U.S. Department of Energy on Home LED Replacement Lamp 2011 (Table 1.), very few of the 38 different lamps had a CCT (correlated colour temperature) under 3000 K. I think in replacement lamps it needs to be actually a bit under the ~2700 K of incandescent lamps to look as warm – if that is the aim.

Colour rendition

In photography and cinematography, the colour rendering capacity of the light source is of essence. Here is an example from a highly informative ScreenLight & Grip newsletter:


CRI hi&lo (ScreenLight & Grip)

The newsletter author comments:

I also wouldn’t try to light a table-top food/product shot with LEDs either. As is readily apparent in the shots above, because of their limited color rendering capability, food presentation that will look vibrant and colorful to eye, under LEDs will tend to look a little dull on camera. By comparison a full spectrum daylight source such as HMI or LEP will capture the vibrant colors. Likewise, I wouldn’t try to mix LEDs with a uniform continuous light source, such as a studio lit with tungsten fixtures. If caught in isolation, their color deficiencies will be quite noticeable and unacceptable in comparison to the tungsten.

Colour shift

Even the unusually good looking warm-white colour of Philips’ next best LEDs may not last, as the light is not produced by RGB (mixing of red-green-blue light to produce white, which is also an option in LED) but by blue diods behind a yellow phosphor mix coating on the inside of the yellow parts of the bulb.

It is common for phosphor-based light sources that the phosphors that produce the red part of the spectrum get consumed first, turning the light more and more blue or green as it ages, and LED phosphors are no exception.

LED colour shift
(image from SceenLight & Grip)

There is an electronics store in Stockholm (Kjell & Co) where the counters are lit from above with rows of LED reflector lamps, of which some have been replaced. The result is exactly like the example in the top right photo above. Not very attractive. And the whole atmosphere of the store feels more like a morgue than someplace I love to go shopping, even though I like their products.

In ‘cheaper’ (well, comparatively speaking) LEDs, such as those mentioned above, this colour shift can be seen fairly soon.

Possibly, this may be avoided in the L-Prize bulb which has some red diodes inside and not just blue, so it will not be dependent on the red-producing phosphors to stay warm-white?

And if you have wondered why colour uniformity even in new warm-white LEDs seems so hard to achieve, it depends not only on the phosphor mix but also, apparently, on the diods themselves. The ScreenLight & Grip e-newsletter explains it well:

Given the irregularities inherent in the manufacture of the semiconductor wafers from which White Phosphor LEDs are stamped, the LEDs in a production batch are all slightly different. In a mechanized testing procedure, they are sorted and grouped together into bins according to their flux and color. Binning has been refined over the years, and these days the tolerance of the best binning systems allow barely perceptible differences between LEDS from a selected bin. The difference in color between two sources is quantified using what is called the “MacAdams ellipse.” A MacAdams ellipse defines the distance at which two colors that are very close to one another first become distinguishable to the human eye as different colors. As illustrated below, for a given point of color on the chromaticity diagram, the MacAdams ellipse defines the contour around it, where the colors that surround the point are no longer indistinguishable from that of the point.

Unfortunately, even the L-Prize testing committee finds colour variations acceptable for home lighting LEDs, as can be seen in the Technical Review document [credit to Freedom Lightbulb for finding a copy of it!] under the point Color maintenance (emphasis added):

Variation among submitted samples are well within the allowed limit. However, Philips asks for less tight tolerance for the production lamp, proposing a 0.006 variation limit. Although there are some concerns about users perceiving a slight difference in color appearance between lamps, Philips indicates that a ∆u’v’ of 0.006 is the maximum boundary and 90% of the production lamps will fall within a 0.004 ∆u’v’boundary. Given that an absolute tighter tolerance is a trade-off with cost, the TSC believes this tolerance to be acceptable. 

In the latest CALiPER test by U.S. Department of Energy on Home LED Replacement Lamp 2011 with samples of A19 bulbs, G25 globes and MR16 and PAR20 reflector lamps, colour variations were between 0.0010 and 0.0100! Not that I’m quite sure what such numbers translate to visually, but if Philips and the prize committee sees a variation of 0.004 or 0.006 something to haggle over, then it certainly sounds significant.


The ScreenLight & Grip e-newsletter also explains the difficulty in getting LEDs to dim as easily and beautifully along the Planck curve as incandescents do.

Another problem is that, while it is relatively easy to put a dimmer on an LED, and blend two different color LED chips to achieve variable color mixing, as we saw above it is quite a different matter to track the color so that it remains on the black body locus at every point from daylight balance to tungsten balance. Maintaining a specific color temperature at a high CRI while dimming is made even more difficult by virtue of the fact that temperature in the LED changes when they are dimmed. Change in temperature shifts output wavelength as well as efficiency, and different LED chips change efficiency at different rates and at different temperatures. For these reasons, a more complex approach to dimming is required in order to control all these factors.

And as noticed by Save The Bulb, even the best LED replacement bulb available on the market today, Philips Master LED (same family as the L-Prize LED bulb) doesn’t dim very well (emphases added):

The [LED lamp] got cooler in appearance and the perceived colour rendering became much worse casting a gloomy grey in the space.

[T]he lamp also suddenly went out about half way through the travel of the dimmer’s slider, the GE lamp dimmed right down to the minimum setting. What was really alarming was that the [LED] lamp would not switch on at dimmer settings below about 70%. This was a serious problem in this location where three way switching was installed.

Really I am somewhat disappointed in a product that cost me $19.75 and does not work reliably at less than full power even when it claims to be dimable. Solutions such as this must be made fully compatible with existing wiring infrastructure.

Dimming incandescent

GE Reveal fulll on and dimmed
(photo: Save The Bulb)

Dimming LED

Philips LED fulll on and dimmed
(photo: Save The Bulb)

My comments:

1. Note how the LED, even when turned on fully, is not quite as warm as the blue-enriched GE Reveal incandescent lamp.

2. Note also how the LED (being a directional light forced into an omnidirectional bulb) mainly illuminates the ceiling area and leaves much of the corridor in the dark, whereas the incandescent lights up the whole space more evenly.

3. And finally, how the incandescent dims nicely along the Planck curve and gets warmer without losing light quality, as the light from all natural light sources always behaves. Whereas the LED light indeed turns into a gloomy blueish grey.

The L-Prize committee technical review says:

Capable to at least 20% dimming of maximum output without flicker.

Although the initial dimmers designated by Philips did not appear to be widely available and testing conducted by PNNL with a wide variety of dimmers showed several issues with the subnitted lamps, Philips redesign of the driver for the production lamps will meet these criteria. Philips has also stated that they will reveal any known incompatibilities in their product literature and on their website. 

That doesn’t sound overly reassuring…

Instead of searching Philips already hard-to-navigate website for info on which dimmers may be incompatible, I think I’ll just avoid putting any Philips LED bulb in any of my dimmable fixtures (I’ve already fried one dimmer when I thoughtlessly tested a CFL). I believe the reason some CFLs and LEDs are made dimmable is primarily to make them work with existing installed dimmers without blowing the circuits, not to actually be dimmed.

Power Factor

According to the CALiPER test mentioned earlier, Home LED Replacement Lamp 2011, Power Factor on tested lamps ranged between 0.38 (!) and 0.99.

And the L-Prize testing committee found it perfectly acceptable with 0.70 PF even for the best LED lamp, when used at home:

…and explains why (my emphasis):

Power Factor for submitted lamps meets both criteria. However, the production lamp design does not meet the L Prize criteria for commercial applications, but all lamps will be greater than 0.7. The TSC finds this acceptable as it understands the lower power factor is a trade off with more universal dimming performance and that an important early market for the L Prize lamp is the residential market. 

But this bulb is absolutely useless for dimming! So what’s the point in trading away better PF for a desired function that it flatly fails on?


The excellent German site Argumente für die Glühbirne [thanks again to Freedom Lightbulb for the link] reports that consumer magazine Ökotest (‘Eco-test’) issue 11/2011, found LEDs to flicker! How much varied between brands. Flicker in the 11 test specimens was:

2 LEDs extremely pronounced
5 LEDs pronounced, but also on higher radiofrequency
1 LED pronounced
3 LEDs weak, but also at higher frequencies

Rare elements

From another page on the Glühbirne site (translated by google):

The 17 rare earth metals include cerium, dysprosium, erbium, europium, gadolinium, holmium, lanthanum, lutetium, neodymium, praseodymium, promethium, samarium, scandium, terbium, thulium, ytterbium, yttrium.

Rare-earth metals are not rare. The name comes from the fact that they originally found in rare minerals were. Some of the rare earth metals are more common in the earth’s crust than other elements, but larger deposits of suitable minerals are rare indeed.

China dominates the market for rare earths.

2010 was the share of world market at 97 percent.

2011 China has reduced the export volumes for the umpteenth time.

For some metals (yttrium, thulium and terbium which are required for CFLs) there is a complete export ban.

Following referenced links to Send Your Light Bulbs To Washington, which in turn quotes a Light Bulb Choice blog post, quoting
renewableenergyworld.com and conexiones.com):

Huge Price Increases Underway from Lamp Manufacturers: The impact of rare earth metals shortages

There is a rapid, emerging shortage of rare earth metals, a primary component used in the manufacture of fluorescent lamps – principally phosphors. Phosphors are transition metal compounds or rare earth compounds of various types. The most common uses of phosphors are prevalent in green technologies such as batteries, magnets, computer hard drives, TV screens, smart phones, and energy-saving light sources – and fluorescent lamps.

The problem with the supply of rare earth elements is that demand has skyrocketed over the last decade from 40,000 tons to 120,000 tons. Meanwhile, China, who owns the monopoly of rare earth minerals has been cutting its exports. Today, it only exports about 30,000 tons a year – only one-fourth of the world’s demand.

In a U.S. Department of Energy report dated December 14, 2010, it was noted that ”it is likely to take 15 years for the U.S. to mine enough rare earth minerals to shake its dependence on China.”

With China currently controlling up to 97% of the world supply of rare earth metals, it shouldn’t come as a surprise that they’ve been imposing tariffs and severe export restrictions.

More from Journal of Energy SecurityThe Battle Over Rare Earth Metals

Also, as reported in a 2-page article in New York Times: Earth-Friendly Elements, Mined Destructively with sad pictures of ruined landscape, there is nothing environmentally friendly about how rare earth metals are mined in China (emphasis added):

Here in Guyun Village, a small community in southeastern China fringed by lush bamboo groves and banana trees, the environmental damage can be seen in the red-brown scars of barren clay that run down narrow valleys and the dead lands below, where emerald rice fields once grew.

Miners scrape off the topsoil and shovel golden-flecked clay into dirt pits, using acids to extract the rare earths. The acids ultimately wash into streams and rivers, destroying rice paddies and fish farms and tainting water supplies.

On a recent rainy afternoon, Zeng Guohui, a 41-year-old laborer, walked to an abandoned mine where he used to shovel ore, and pointed out still-barren expanses of dirt and mud. The mine exhausted the local deposit of heavy rare earths in three years, but a decade after the mine closed, no one has tried to revive the downstream rice fields.

Small mines producing heavy rare earths like dysprosium and terbium still operate on nearby hills. “There are constant protests because it damages the farmland — people are always demanding compensation,” Mr. Zeng said.

“In many places, the mining is abused,” said Wang Caifeng, the top rare-earths industry regulator at the Ministry of Industry and Information Technology in China. 

“This has caused great harm to the ecology and environment.”

Many mining operations are even run by gangsters:

Half the heavy rare earth mines have licenses and the other half are illegal, industry executives said. But even the legal mines, like the one where Mr. Zeng worked, often pose environmental hazards.

A close-knit group of mainland Chinese gangs with a capacity for murder dominates much of the mining and has ties to local officials, said Stephen G. Vickers, the former head of criminal intelligence for the Hong Kong police who is now the chief executive of International Risk, a global security company. 

Telling illegal ore from legal does not seem possible:

Western users of heavy rare earths say that they have no way of figuring out what proportion of the minerals they buy from China comes from responsibly operated mines. Licensed and illegal mines alike sell to itinerant traders. They buy the valuable material with sacks of cash, then sell it to processing centers in and around Guangzhou that separate the rare earths from each other.

Companies that buy these rare earths, including a few in Japan and the West, turn them into refined metal powders.

Besides these rare earth metals and a stunning amount of electronic components (commented on by FreedomLightbulb), LEDs also contain, depending on colour, other elements, such as indium, gallium, aluminium or zinc.

Plus arsenic, lead, nickel “and many other metals”, as reported earlier (emphasis added):

Oladele Ogunseitan, chair of UC Irvine’s Department of Population Health & Disease Prevention [] and fellow scientists at UCI and UC Davis crunched, leached and measured the tiny, multicolored lightbulbs sold in Christmas strands; red, yellow and green traffic lights; and automobile headlights and brake lights. Their findings? Low-intensity red lights contained up to eight times the amount of lead allowed under California law, but in general, high-intensity, brighter bulbs had more contaminants than lower ones. White bulbs contained the least lead, but had high levels of nickel. 

With incandescent lamps, it was just a glass bulb, a tungsten filament and an aluminium base…

…that produced an easily & beautifully dimmable, naturally warm light of the highest quality, power factor and all the rest. 

More on LED issues from ABC: Are LED lightbulbs worth the extra money?

Lighting industry on LED issues

For those who still believe LED bulbs to be the perfect incandescent replacement, be advised that leading lighting industry representatives don’t seem very convinced themselves. Here are some of their views ‘straight from the horse’s mouth’ in 2009 and 2012.


In May 2009, EDN’s Designing with LEDs seminar invited Francis Nguyen, senior product marketing manager at OSRAM, Willem Sillevis-Smitt, director of strategic marketing at Philips Lumileds, and Paul Scheidt, product manager at Cree Components, to discuss LED issues and the future of LEDs. Quoting part of the article LED lighting: panel debates quality versus cost here (emphases added).

Conference chair and EDN editor Margery Conner opened the discussion with a simple question—why can’t we just use banks of ordinary 5mm industrial white LEDs for lighting?

The answer turned out to be less than simple. For one thing, Scheidt said, a typical 5mm LED produces about 6 lumens. So a big commercial fixture would require thousands of LEDs, creating interesting problems for driver designers, and in the end consuming about the same power as a florescent fixture of the same output. “The big advantage for LEDs in lighting applications comes when you design the LEDs for that purpose,” Scheidt said. “Then you can achieve output efficiency, directability of the beam, and reliability that you can’t get any other way.”

Nguyen offered a cautionary tale. “I walk through a neighborhood that has lots of those solar-powered LED yard lights,” he said. “And I started noticing recently that more and more of them are burned out. Well, those fixtures actually do use standard 5mm white LEDs. What happens—you can see this if you take one apart—is that the blue light from the LED is intense enough, especially if you overdrive it, to degrade the epoxy encapsulant. The epoxy turns yellow, and then it starts to crack. Once you get a crack, the LED will fail. So this is not a good use of these LEDs.”

The next question was more challenging. How will LED lighting avoid the same sort of problems that compact florescent lamps (CFLs) experienced early in their market life? Sillevis-Smitt weighed in first, explaining that like LEDs, CFLs had started out as high-priced lamps designed for long life. But the lure of the incandescent-bulb replacement market, coupled with the entry of low-cost producers from Asia, quickly drove vendors to trade away the long life in exchange for lower cost. This led to a complex situation in which consumers often don’t understand the characteristics of the lamp they are buying. In fact in many applications, inexpensive CFLs aren’t really direct replacements for ordinary light bulbs at all. But not knowing this, consumers buy the wrong bulb for their purpose and get frustrated when it doesn’t work. That is exactly the situation regulators are now trying to prevent with new standards, Sillevis-Smitt said.

Nguyen added that first of all, designers needed to understand that LED lamps required conductive cooling, while incandescents are designed to survive with only radiative cooling. So LEDs physically could not be screw-in replacements for incandescent bulbs in all applications. And today, he said, the cost per Lumen of LEDs is very much too high to replace incandescents or even CFLs. “Fixtures must exploit the long life of properly-designed LED lighting to have a competitive position,” he said.

Scheidt agreed with both statements. “The EnergyStar standards will be critical to the development of this market,” he said. Also, he underlined that the strength of LED lighting is not its cost, or even its efficiency, but the features that it can offer beyond just illumination. “We have to break people away from the expectation of a screw-in light bulb for very low cost, he said.

A series of questions asked about what the maximum light output of the lamps really was, and whether it was a function of lifetime. Sillevis-Smitt answered that getting the best lifetime out of the lamps meant reading the datasheet, where output-vs.-life data was available. “In general, higher junction temperature and higher current will mean lower life,” he warned. “There are several failure modes on LEDs, but which one is most likely depends on the architecture of the particular lamp.

Doesn’t sound at all as reassuring as when the same lighting technology is presented to the general public with statements like “lasts 25 years”.

The article author (rather astonishingly!) concluded:

“All in all, the panelists seemed confident in the future of LED lighting, but definitely not as a screw-in replacement for incandescent lamps.”


So, how does the lighting industry feel about it now, three years later, when much progress actually has been made in the LED development?

Dr. Charles Hunt, director of the Vu1 Corporation, let us know in his Light-Source Symposium Update review of the 13th International Light-Source Symposium held in Troy, NY, in late June this year:

This is THE scientific conference on lighting sources (lamps) and is held every other year. This year, it was hosted by Rensselaer Polytechnical Institute (RPI) Lighting Research Center (LRC), and held at the RPI campus.  In recent years, this conference has focused heavily on LED and OLED — so-called “SSL” — sources with only a minimal amount of discussion centered on fluorescent, HID, halogen, and other light sources.

The chief technology officers of several important lighting companies (Osram, Philips, GE, Cree, Panasonic, and Toshiba) all spoke on the first day, and, surprisingly, I observed none of the hyperbole or excessive optimism about LED and SSL we’ve experienced in recent years.

In an ensuing panel discussion, one question from the audience was, “Can you list and prioritize the technical challenges with SSL, and can you tell us what the key issue to solve is?”

Without hesitation or disagreement, they listed cost, thermal management, reliability, color quality, electronics, and form factor.  Two of the CTOs agreed that the top two are extremely serious, and necessary to solve before SSL can make significant inroads into the residential lighting markets.  They all agreed that SSL is only relevant at the present for decorative and specialty lighting, especially backlighting. They also agreed that they feel major improvements may come about (ranging in opinion of 1 to 10 years.)

[leaving out part where everyone showed interest in the Vu1 bulb, as irrelevant for this particular article]

With regard to other conference highlights, the consensus is that OLED technology is far too dim, unreliable and too expensive for products at this time; but some years in the future, there should be a crossover in “cost per lumen” which could help them emerge as residential products.

The LED “Blue Light Hazard” is no longer viewed as unsubstantiated fodder for emotional hysteria: all of the LED community is now acceding to the existence of problems with circadian rhythms, melatonin and other hormone production, macular degeneration, disrupted sleep cycles, and other issues, as a result of exposure to LEDs – the potential to be a major worldwide issue.

OK, this description was from the producer of a competing lamp technology, but I have no reason to believe it inaccurate, especially not in view of the earlier panel discussion.

More LED Issues

Found some interesting LED articles at the Swedish National Electrical Safety Board’s website. Not all new, but still worth considering. (Quoting whole articles here, with some corrections to goole’s translation to English. Emphases added.)

LED tubes can be dangerous

May 20, 2010

To save energy, many industries, municipalities and other large consumers of traditional fluorescent lamps are switching to LED lamps. Tests show that LED tubes can compromise the security of the person replacing the lamp.

LED lampsThe new LED tubes are supplied with 230 V voltage to the luminaire lamp holder for the lamp ends. The risk is getting an electric shock when the lamp is replaced because it is easy to touch the shiny connectors at one end of the tube, while the other end is attached to the light fixture.

Can be mounted in standard fluorescent fixtures

The National Electrical Safety Board has been tested a number of LED tubes in the Swedish market. All products can be installed in conventional fluorescent fixtures. The results of the tests show such serious faults that the agency has decided to withdraw the products from end users. Importers are required to advertise alerts to reach all end users.

– The current LED tubes are sold primarily via the Internet and can be found both among consumers as that of bulk consumers, says Martin Gustafsson at the Safety Board. Those who have purchased the product should contact the place of purchase for warranty.

Safety Board has no data on how many of those LED lamps on the market, but there may be a thousand.

The corresponding study in Finland

The Finnish equivalent of the National Electrical Safety Board, Safety Tukes, has been tested a number of led tube. Test results have shown that the tested products did not comply with safety regulations, and there was a risk of electric shock when replacing the tubes. According Tukes there are in Finland several thousand LED tubes that can be dangerous. The Safety Board has contacted the LED tube suppliers in Sweden who have received the Finnish counterpart sales ban in Finland and asked them to take voluntary measures in accordance with the measures Tukes has demanded. The LED tubes tested by the Swedish Safeby board have not been tested in Finland.

LED-lysrör kan vara farliga

So, be careful out there! Turn the power off before mounting LED tubes. And don’t be sure they’ll fit your old fixtures:

LED lamps and fluorescent tube adaptors

July 14, 2009

One way to save energy is to replace existing incandescent bulbs with compact fluorescent bulbs, which are normally without problems.

But even for the traditional fluorescent tubes pops up options on the market. On the one hand, new types of fluorescent tubes that operate at higher frequencies, and also LED tubes. The idea is that you should be able to reuse existing light fittings and just replace the traditional fluorescent tube with one of these new alternative light sources. For this to work, usually you make changes to the original fixture, which can change the properties and affect the electrical safety and electromagnetic compatibility (EMC).

What does the regulatory framework say

A trader who places a product on the market is obliged to take responsibility for this product. A sign of this is that the product is CE marked. If a trader puts together two CE-marked products, he or she is considered the producer of a new third product that he or she is responsible for and which in turn must be CE marked. This reasoning also applies when replacing the lamp in an existing fluorescent light fixture with an option for which the fixture was not originally designed.

A fluorescent light fixture for so-called T8 fluorescent lamps are optimized for this type of light source and have quite different characteristics when mounting an alternate light source. Often you have to modify the existing fixture, remove or replace the starter or other components to work together with the new light source. When doing this, the original CE marking is no longer valid and you are considered the responsible producer of the new product consisting of the modified fixture with the new alternate light source. This applies to each new type of combination of fitting the new light sources.

CE marking and EC Insurance

If the new product meets all the essential requirements for electrical safety and electromagnetic compatibility (EMC), it should again be submitted for CE marking and draw up an EG declaration and technical documentation. Read more in Elsäkerhetsverkets regulation ELSÄK-FS 2000:1 which is available at the website. For safety of the new product, one needs to ask a few questions:

first: If the thermal properties of the original fixture was negatively affected?

second: Is there a risk that the new light sources weighs so much that the lamp holders in the original fixture overload?

third: What characteristics of EMC, the new combination of original fixtures and new light bulbs? Will the new product requirements of the EMC Directive?

More problems

Other issues to consider are how the new product changes light qualities. Both brightness and light distribution can be affected in a way that the requirements for illumination of such a task are no longer are met. There are also other EU directives that you need to consider: WEEE and RoHS are two examples relating to the environmental characteristics. If you are looking to manufacture or import of alternative light sources for T8 fluorescent lamps to resell, you should consider on the liability issue and inform your customers about the responsibility they assume when installing new types of light bulbs in existing fixtures.

LED-lysrör och lysrörsadaptrar

(Again, the mandatory mention of CFLs and their energy saving potential, in an article that has nothing to do with CFLs whatsoever.) Anyways, don’t try this at home.

Banned LED bulbs

Dec 14, 2011

With the new energy conservation requirements, incandescent bulbs be phased out, increasing interest in alternative lighting. The National Electrical Safety Board has recently given a variety of LED lamps sales ban.

The most common reason is electrical grid disturbances, but they also interfere with radio frequencies.The lamps which the Safety Board has looked at are the incandescent bulb replacement LED bulbs. They are based on modern LED technology and all the lamps tested contains a small power pack, situated in the lamp socket.

List of products which have so far received sales ban: Lamp 1Lamp 2Lamp 3Lamp 4Lamp 5Lamp 6Lamp 7. [3 more but links required login]

Result of market supervision

More than half of the LED lights purchased through the market and tested have received sales bans. This is a remarkably high figure, which may be because most of the lights checked had built-in dimming, i.e. that they are dimmable. Dimmable LED lamps contain control electronics that often require specific measures to achieve acceptable properties to make electrical devices work together, known as electromagnetic compatibility (EMC). This is sometimes overlooked by the lamp manufacturers. It is important to you as a manufacturer or importer to ensure that the LEDs have been tested properly with EMC.

How does the disturbance manifest?

LEDs produce disturbances in the distribution system which, among other things, can cause radio interference. Radio interference caused by the conducted noise radiating from the connected wires. This is because the lines, e.g. to the luminaire, act as transmitting antennas for conducted interference. The disturbance may affect other electrical products in the local area, even those that are not connected to an outlet. It can also affect communication such as wireless broadband and telephony.

What rules apply for manufacturers?

The Electrical Safety Authority on electromagnetic compatibility (ELSÄK-FS 2007:1) has to be followed. Regulations based on the EMC Directive (2004/108/EC EMCD).

Cooperation within the EU about LED lights

There is currently a campaign in the EU where LED lighting examined. The aim is to investigate if the new LED lights on the market comply with applicable EMC requirements.

Förbjudna LED-lampor

A few months later, EU authorities found similar problems:

Disruptive LEDs are examined in the EU

Feb 10, 2012

The National Electrical Safety Board has in 2011 looked into LED lights, half of which got sales bans. The reason for the bans is that the lights did not meet the applicable requirements for electromagnetic compatibility (EMC).

Market of LED lamps 2011The lights disrupted other electrical products. Only one in five LED lamps passed the test without comment.

European survey

In parallel with the National Electrical Safety Board’s market surveillance of LED lights, the EU carried out an investigation. The EU surveillance is not strictly comparable to the Safety Boards’s market surveillance, but shows similar shortcomings. The results also show that manufacturers who use LED technology are very poor at complying with the Directive.

– The reason for this is that LED technology is so new and there have appeared many new manufacturers in the market that are simply not aware of the directive, said Ulf Johansson at the Safety Board.

Clearer rules

One of several measures aimed at improving the situation is that the European Commission gives the European Committee for Standardisation mandate to supplement and clarify standards in the field. The aim is to help traders in the market to more easily use the current rules.

Continued control

The National Electrical Safety Board will, in line with other market surveillance authorities in the EU, check the LEDs in 2012 as well. It also plans to follow up on last year’s surveillance with a campaign aimed at improving information about the LED lights.

Störande lampor granskas i EU

Final Report on the 4th Cross-Border EMC Market Surveillance Campaign – 2011 LED Lighting Products

No comments necessary, I think.

LED Drawbacks

Time to write a little summary about solid state lighting a.k.a. LED and what has transpired over the last couple of years.

Coloured LED

As I’ve written before, I’m all for the use of coloured LEDs as replacement for holiday light strings, night lights, exit signs and traffic lights that are used for so many hours per day.

Warm-white LED

I have yet to see a warm-white LED that looks like a decent incandescent replacement. I went to the Nordic Light Fair again last year too but the warm-white LED lamps had not much improved. (I’ll keep checking.)

Update Aug 2012: This summer I’ve seen some good-looking warm-white LEDs, first at the Arlanda Airport and as streetlights in a Stockholm suburb, and then yesterday I got a look at Philips MyAmbiance LED bulb in a Swedish hardware store. So, it seems it can be done. However, these examples are from the very top end of the market – at the beginning of their life. The majority of LED bulbs for the consumer market still look absolutely horrid.

Cool-white LED

The glaring cool-white LEDs I find hard on the eyes and not at all suitable for Scandinavia, where we are used to the warm glow of incandescent light in the winter time. Two years ago they tried replacing the lamps by the creak in one of Sweden’s most picturesque little towns to cool-white LED, but had to remove them quickly as the result was ghastly and people complained. Now that town is lit by incandescent-looking ceramic metal halide and warm-white good quality CFLs, which is ok even though quite not as pretty and romantic as when it had real incandescent lamps along the waterside.

I also recently checked out an LED-lit tunnel in Stockholm and found the bright cool-white light dangerously glaring. Much more so than the standard linear fluorescent or sodium HID lamps usually used in tunnels (and I’m not crazy about those either). Shops lit with LEDs tend to look cold and sterile, rather than warm and inviting. Could be that I’m female, many men seem to love the cold harsh light. Here is a similar opinion from another woman (emphasis added):

Whenever I try to study in Meriam Library I feel like I’m on an examination table in a surgery room. Either that or in a jail cell or a mental institution. The lights are overly bright and they make a buzzing noise that interferes with my ability to concentrate. I’ve stopped going. /…/

Now, whenever I walk up the Esplanade to get home at night, I notice that the LED bulbs cast a sharp bluish-white light that brightens the whole street. I understand that peripheral visibility will greatly increase for drivers, but they are just too bright.

They remind me of Meriam Library but on greater scale.

If these energy-efficient bulbs take over streets and even in-house lighting, you have to ask yourself – do I want everything around me to feel like a night game of football or baseball?

What’s worse is that these lights will affect space observatories in cities across America, causing an effect that doesn’t seem be taken as serious as when smog from cars damages air quality. That effect is called light pollution.

LEDs are actually more dangerous than the old incandescent bulbs because they cause a glare for drivers and create more shadows, said Kris Koenig, director of the Kiwanis Chico Community Observatory.

“Cities are going to want to open light again where they’ve been restricting light for decades,” Koenig said, in a phone interview. “There are even studies that show that light at night causes sleep problems for humans and animals.”

LEDs trade comfort for brightness

Toxic LED?

And last year scientists found that LEDs – like most electronic products, surprise surprise – contain some toxins too (my emphasis).

“LEDs are touted as the next generation of lighting. But as we try to find better products that do not deplete energy resources or contribute to global warming, we have to be vigilant about the toxicity hazards of those marketed as replacements,” said Oladele Ogunseitan, chair of UC Irvine’s Department of Population Health & Disease Prevention.

He and fellow scientists at UCI and UC Davis crunched, leached and measured the tiny, multicolored lightbulbs sold in Christmas strands; red, yellow and green traffic lights; and automobile headlights and brake lights. Their findings? Low-intensity red lights contained up to eight times the amount of lead allowed under California law, but in general, high-intensity, brighter bulbs had more contaminants than lower ones. White bulbs contained the least lead, but had high levels of nickel. 

“We find the low-intensity red LEDs exhibit significant cancer and noncancer potentials due to the high content of arsenic and lead,” the team wrote in the January 2011 issue of Environmental Science & Technology, referring to the holiday lights. Results from the larger lighting products will be published later, but according to Ogunseitan, “it’s more of the same.”

Lead, arsenic and many additional metals discovered in the bulbs or their related parts have been linked in hundreds of studies to different cancers, neurological damage, kidney disease, hypertension, skin rashes and other illnesses. The copper used in some LEDs also poses an ecological threat to fish, rivers and lakes.

Ogunseitan said that breaking a single light and breathing fumes would not automatically cause cancer, but could be a tipping point on top of chronic exposure to another carcinogen. And – noting that lead tastes sweet – he warned that small children could be harmed if they mistake the bright lights for candy.

LED products billed as eco-friendly contain toxic metals, study finds

I must say that I find that risk a lot smaller than accidentally breaking a CFL at home and breathing the mercury vapour. Breaking an LED is not so easy (although I managed to drop one and broke the outer bulb) and you normally don’t pulverise them (“don’t try this at home!”). But they should absolutely be recycled as electronic waste and not thrown in out with household garbage.

(As an aside: In connection with this article being quoted around the web I’ve also seen some erroneous claims that incandescent lamps contain mercury – which is not true at all – and lead, which used to be true but not after 2006.)

Long-life LED?

Promised longevity may also not be what one expected:

When it’s said that a standard light bulb will last 1,000 hours, that is the mean time to failure: half the bulbs will fail by that point. And because lamp manufacturing has become so routine, most of the rest will fail within 100 hours or so of that point.

But LED lamps don’t “burn out.” Rather, like old generals, they just fade away.

When a manufacturer says that an LED lamp will last 25,000 or 50,000 hours, what the company actually means is that at that point, the light emanating from that product will be at 70 percent the level it was when new.

Why 70 percent? Turns out, it’s fairly arbitrary. Lighting industry engineers believe that at that point, most people can sense that the brightness isn’t what it was when the product was new. So they decided to make that the standard.

Of course, brightness is subject to the old frog in the boiling water syndrome. I’m sure that most people won’t even notice the lower level then, if they’ve lived with the same bulb for its entire life.

How Long Did You Say That Bulb Would Last?

Philips & Color Kinetics explains it more in detail:

This 70% of the level of original output is called L70 by the lighting industry. ASSIST recommends defining useful life as the length of time it takes an LED light source to reach 70% of its initial light output (L70). For decorative and accent applications, ASSIST recommends defining useful life as the length of time it takes an LED light source to reach 50% of its initial output (L50).

So up to 30-50% is seen by the lighting industry as a perfectly acceptable level of light loss just because we get used to it over time??

Testing also seems difficult, making one wonder how the life span numbers given for LEDs are arrived at (emphasis added):

LM-80 requires testing of LED light sources for 6,000 hours, and recommends testing for 10,000 hours. It calls for testing LED sources at three junction temperatures — 55° C, 85° C, and a third temperature to be determined by the manufacturer — so that users can see the effects of temperature on light output, and it specifies additional test conditions to ensure consistent and comparable results.

Unfortunately, LM-80 provides no recommendations on how to extrapolate measured data to L70 or L50. Such a methodology, IES Technical Memorandum TM-21 is currently under development. Until TM-21 is published, the only way an LED source manufacturer can claim that their L70 and L50 figures conform to LM-80 is to measure their LED sources until they reach those thresholds. Since a typical L70 number is 50,000 hours, such a test would last longer than five years! Not only would this test be impractical, but LED technology evolves so quickly that a given product would be obsolete by the time the test was completed.

Philips & Color Kinetics: Useful Life Technical Brief