Climate Change

[only_human]

I haven't been following this thread but on the issue of light flicker, it seems that a false assumption is prevailing. The light flicker rate is twice the power line frequency because the voltage crosses 0 twice in a cycle.

This seems to be a nice description about flicker and headaches etc.
http://www.ccohs.ca/oshanswers/ergon...g_flicker.html

What is light flicker?
Can you actually see lights flicker?
Are there any health effects associated with light flicker?
What kind of things can cause light flicker or dimming?
What kind of lighting is likely to cause a flicker problem?
What can be done to reduce or eliminate light flicker?

[cheesehead]

Originally Posted by only_human

I haven't been following this thread but on the issue of light flicker, it seems that a false assumption is prevailing. The light flicker rate is twice the power line frequency because the voltage crosses 0 twice in a cycle.

I suspect we all understand that, after a moment's thought anyway, so there is really no false assumption prevailing, and the uses of "50Hz" and "60Hz" are simply habitual references to the prevailing AC frequencies of which the flicker rate is twice.

Thanks for the CCOSH link.

Hmm... They're pretty definite about there being a fluorescent effect. I wonder if the study whose results they quote controlled for light intensity as well as bulb type. ... and spectrum -- it could be the difference in intensity distribution along the wavelengths (red -> blue) between the two types.

But note the difference between magnetic ballasts and high frequency electronic ballasts (20,000 Hz or higher). Could the hum play a role?

They don't mention migraines specifically, just "headaches".

. . .

Although humans cannot see fluorescent lights flicker, the sensory system in some individuals can somehow detect the flicker. Ever since fluorescent lighting was introduced in workplaces, there have been complaints about headaches, eye strain and general eye discomfort. These complaints have been associated with the light flicker from fluorescent lights. When compared to regular fluorescent lights with magnetic ballasts, the use of high frequency electronic ballasts (20,000 Hz or higher) in fluorescent lights resulted in more than a 50% drop in complaints of eye strain and headaches. There tended to be fewer complaints of headaches among workers on higher floors compared to those closer to ground level; that is, workers exposed to more natural light experienced fewer health effects. [Wilkins, A. J., Nimmo-Smith, I., Slater, A. & Bedocs, L. (1989). Fluorescent lighting, headaches and eye-strain. Lighting Research and Technology, vol. 21, 11-18]

. . .

What can be done to reduce or eliminate light flicker?

Some types of ballasts can reduce flicker considerably. New, energy-efficient electronic ballasts take the 60 Hz power and convert it to voltages at a much higher frequency (20,000 - 60,000 Hz). The resulting flicker frequency (twice the supplied power frequency, 40 -120 kHz) is so high that the human eye cannot detect any fluctuation in the light intensity - essentially flicker-free. An added benefit is that electronic ballasts produce less hum than that emitted by other kinds of ballasts.

To correct flicker:

• Replace bulbs on a scheduled basis. Old bulbs tend to flicker more and they are not as bright.
• Ensure that all parts of the light fixture, especially the ballast, are functioning properly.
• When replacements are needed, upgrade to fluorescent lighting that uses electronic ballasts.

[petrw1]

This winter, where I live (Saskatchewan, Canada) was one of the coldest on record....every month from December to March was below average temperatures.

[AES]

Originally Posted by petrw1

This winter, where I live (Saskatchewan, Canada) was one of the coldest on record....every month from December to March was below average temperatures.

I suppose the CFL's didn't brighten up very quickly under those conditions.

[petrw1]

Originally Posted by AES

I suppose the CFL's didn't brighten up very quickly under those conditions.

We don't even use them outdoors in the winter ... you don't have to go much below 0F before they turn on VERY slowly if at all ... don't even try -40F.

[only_human]

Originally Posted by cheesehead

I suspect we all understand that, after a moment's thought anyway, so there is really no false assumption prevailing, and the uses of "50Hz" and "60Hz" are simply habitual references to the prevailing AC frequencies of which the flicker rate is twice.

Thanks for the CCOSH link.

Hmm... They're pretty definite about there being a fluorescent effect. I wonder if the study whose results they quote controlled for light intensity as well as bulb type. ... and spectrum -- it could be the difference in intensity distribution along the wavelengths (red -> blue) between the two types.

But note the difference between magnetic ballasts and high frequency electronic ballasts (20,000 Hz or higher). Could the hum play a role?

They don't mention migraines specifically, just "headaches".

I found that ballast information very interesting too. In the typical CFL we throw out the ballast every time the bulb is changed. Smart Lite from 3E Technologies has a product that separates the two. In a more sensible world we would have lamps with built in but replaceable ballasts in them and choose the best ballast possible regarding cost, durability and comfort.

I don't think we are really playing our "A" game yet with green efforts. Many people who begin a food diet, obsess over the items they eliminate and seek out substitutes that rarely satisfy. That's a bit of what's happening with CFLs I think.

Heat dissipation and safety requirements necessitate a different lamp for halogens and no one makes a fuss. Why not a sensible lamp for household florescent bulbs too?

I worked a bit in the television world in the past and I was told that older people are less sensitive to television flicker rates and also that the engineers and developers tended to be a bit older than the average bear. Taken with a grain of salt.

Ross

[__HRB__]

Originally Posted by petrw1

This winter, where I live (Saskatchewan, Canada) was one of the coldest on record....every month from December to March was below average temperatures.

Since you are trying to refute the irrefutable existence of global warring [sic] with anecdotal evidence, you're obviously an illiterate white-trash neo-nazi redneck selfish capitalist republican fascist trying to make the morally superior neighbor of the corporate Sodom & Gomorrah look bad.

Anecdotes are not data, so this is clearly even more evidence that the opposite must be true and that global warring [sic] is not only a hoax, but indeed the ultimate threat to mankind.

Since people like you hate mankind, The Children™, kittens and everything else that is good in the world, the most important thing is to ensure that super-humans like cheesehead determine the fate of the human race - by force if necessary - so that sub-humans like you will not destroy the universe with your immoral stupidity.

[Uncwilly]

Originally Posted by only_human

In the typical CFL we throw out the ballast every time the bulb is changed.

You should take the CFL to your local e-waste place.

I have actually held in my hand some LED lamps with the standard screw bases that are mini-flood style. They weren't cheap, but they have about 1/3 the wattage of the CFL(IIRC).

[retina]

Originally Posted by __HRB__

Since you are trying to refute the irrefutable existence of global warring [sic] with anecdotal evidence, you're obviously an illiterate white-trash neo-nazi redneck selfish capitalist republican fascist trying to make the morally superior neighbor of the corporate Sodom & Gomorrah look bad.

Anecdotes are not data, so this is clearly even more evidence that the opposite must be true and that global warring [sic] is not only a hoax, but indeed the ultimate threat to mankind.

Since people like you hate mankind, The Children™, kittens and everything else that is good in the world, the most important thing is to ensure that super-humans like cheesehead determine the fate of the human race - by force if necessary - so that sub-humans like you will not destroy the universe with your immoral stupidity.

Wow, you inferred all that from one small message on a forum?

[only_human]

Originally Posted by Uncwilly

You should take the CFL to your local e-waste place.

I have actually held in my hand some LED lamps with the standard screw bases that are mini-flood style. They weren't cheap, but they have about 1/3 the wattage of the CFL(IIRC).

You are completely correct; it's the little slips that reveal or surprise the most. A bit funny to talk about discarding when talking green. Especially something that possibly has reclaimable items and also has mercury and maybe phosphorus.

[Uncwilly]

Originally Posted by only_human

You are completely correct; it's the little slips that reveal or surprise the most. A bit funny to talk about discarding when talking green. Especially something that possibly has reclaimable items and also has mercury and maybe phosphorus.

I am constantly on co-workers (who really do know better and should be on the bleeding edge of the green revolution) when they talk about throwing out paper, etc. Breaking the old speach and thought patterns is vital. This is a principal that is used for by those that wish to achieve various goals. If you wish to be successful, dress, talk, and act like those that are successful. This is also a way that we teach children, we model behaviour and speak of things that we want them to understand to be important. Also, memes and names allow us to think differently. One of the best examples, "designated driver".