View Full Version : Fluorescent lites

02-03-2008, 03:46 PM
I had a real bad headache all day Saturday. In this mornings paper an article stating one major cause of headaches is fluorescent lighting......DAM just installed 4 -4tube lites in my shop about 3 months ago. Been replacing incandescents in the house with those cf's.....Just can't win...

02-03-2008, 03:51 PM
The 6500K spectrum bulbs may be closer to natural light. You might give them a try.

02-03-2008, 04:13 PM
You might also try switching to electronic ballasts as they don't flicker like the conventional ballasts do. That may be a significant factor.

02-03-2008, 04:18 PM
You might also try switching to electronic ballasts as they don't flicker like the conventional ballasts do. That may be a significant factor.

If this becomes an everyday occurrence I'll try that.
Thanks Willy

Your Old Dog
02-03-2008, 05:06 PM
regular flourescent tubes absolutly give me a headache if working under them long enough, the cf jobs don't seem to bother me at all.

J Tiers
02-03-2008, 05:09 PM
STRONGLY doubt it is the flicker, which is actually minimal, due to the phosphor coating smoothing it out.

The MAIN problem with fluorescent lights is the "cool white" bulbs that are cheap and used everywhere.

That light gives me a feeling that my eyes are being pulled out of my head. To counter-act it, I install at least one "warm white" or similar light in every fixture or array, and that seems to help quite a bit.

"Warm white", "kitchen and bath", "daylight", almost any of those works. The idea is to get more "red" into the light. That frosty cold blue light from the "cool white" bulbs is bad.

02-03-2008, 05:19 PM
JT, that is what I feel like when I use cheap binoculars or rifle scopes.

02-03-2008, 06:21 PM
I think you will find that a lot of the newer Cf's are high frequency units that shouldn't give any flicker. The larger fluorescent that have a ballast choke definately flicker or strobe, I seem to remember in the past that they were not reckomende for rotating machinery because of the stobe effect on rotating objects. I think you can get high frequency units for larger tubes albeit at ahigher cost, aint it always the way of things!!

J Tiers
02-03-2008, 08:21 PM
I think you will find that a lot of the newer Cf's are high frequency units that shouldn't give any flicker. The larger fluorescent that have a ballast choke definately flicker or strobe, I seem to remember in the past that they were not reckomende for rotating machinery because of the stobe effect on rotating objects.

They won't "freeze" a rotating object. There is always a persistent "green flash" that allows you to see the object as spinning.

Possibly old ones had a shorter duration phosphor.

02-03-2008, 08:31 PM
Headaches from fluorescent lights is well documented phenomena associated with the flicker found in fixtures without electronic ballasts. Compact fluorescents are not subject to this because they of course have an electronic ballast,( which may self-destruct!).

Color temperature also is a factor. Blending incandescents with fluorescents is a good way to ease the strain prevalent with that cold knock your eyes out cold blue light.

Some people obviously are more sensitive to the strobe effect from fluorescents than others, but the number that are effected is quite significant. I personally have no problem with it myself as I have new fluorescents with electronic ballasts in one shop and old style ones in the other and don't have a problem with either one, but I do have guests that are affected by the old ones. But that's a good thing cause then they'll leave.:D

02-03-2008, 10:35 PM
I have a lot of dual 4 ft fixtures in my shop. In each one I installed one warm white and one 'day glo' tube. That's so much better than two cheap cool whites. I had the opportunity to compare the difference a year or so ago when one of the fixtures started weakening. I bought two cool whites 'cause they were cheap and I just wanted some light back in that area. Put the new tubes in, yuk I hate it.

I must have about 20 cfs now in various places. I like the warm white and the daylight, but I don't like the cools. Same deal. I thought I might find the cfs annoying, at least after some time, but that hasn't happened yet. The most annoying thing is that some are slow to start. Most take a few minutes to come to full brightness, but if they don't start up within two or three seconds at a reasonable brightness, they go back to the store.

I don't typically have single sockets where I replace an incandescent with a cf, except a couple hallway lights, so I do the same routine I did before with the tubes- make each pair one warm white and one daylight. I haven't had any ill feeling working for long periods under that combination.

Those hot halogens- not for me either. The larger shop type lights, sodium halide or whatever they are- I don't like them but I'm ok if I don't look at them. They are closer to daylight, but still work off a standard ballast, so there's the flicker factor that could be causing my dislike of them.

J Tiers
02-03-2008, 11:22 PM
Headaches from fluorescent lights is well documented phenomena associated with the flicker found in fixtures without electronic ballasts. Compact fluorescents are not subject to this because they of course have an electronic ballast,( which may self-destruct!).


"Swinging eye test" shows essentially ZERO flicker with all the flourescent fixtures I can find to check. This consists in swinging your gaze across the area without focusing.

With an LED-based light, it is usually possible to see a very plain "dotted line" of flashes. Most LED traffic lights do that, for instance.

I cannot detect it in the fluorescents here. I can see a slight shadowing on rotating cutters, so there is SOME change of intensity, but it is slight.

If it is hard to find when you WANT to find it, it may not be sufficiently large for a measurable effect.

It leads me to seriously question whether the "studies" have controlled for the proper things and found the real effect.

Did they contrast a "DC fluorescent" (obviously zero flicker but same light) with an "AC fluorescent"? Or did they just contrast fluorescents with another type of lamp?

02-04-2008, 02:51 AM

Did they contrast a "DC fluorescent" (obviously zero flicker but same light) with an "AC fluorescent"? Or did they just contrast fluorescents with another type of lamp?

Not sure JT, but I sincerely doubt it, I'm sure a lot of these "studies" are knee-jerk to say the least. I certainly can't speak from first hand experience as it doesn't effect me in the least, but I do think the issue is real enough for some people. I really can't see a detrimental effect emanating from DC fluorescents because as you pointed out, there cannot be any flicker from a direct current source. But according to the "studies" a high frequency electronic ballast operating at 20-60 khz does not effect those that are susceptible to the 60 hz flicker.

As I said, it's a non issue with me so I don't even know what all the fuss is about. I'm just being the devil's advocate as it were.

Just do a search for "fluorescent flicker headaches" and I'm sure you'll find enough ammo to initiate a government grant!

Here's a few to get you started:




02-04-2008, 03:05 AM
When I was a teenager ( yes I can remember that far back) I played around with fluorescent tubes. The neatest one I had was brilliant green- but that's irrelevant. I had made a pulse circuit with a transformer and the output was voltage spikes, pulses with mostly dead times between. I fed it to a fluorescent tube and was able to make it flash. We took pictures at night of my friend running in front of the camera- got three or four sharp images in a row of him on one of the pictures. The phosphor was obviously responding fairly quickly to the pulses.

Running off a ballast I can see the 'on' time of a tube being longer than the off time, and I can also see some on time with weaker voltage and thus weaker light output. The tube may well be putting out a resonably even amount of light for most of each half-cycle, but it is dimming down a lot during the low voltage periods. If it wasn't for this, my strobe discs wouldn't be working at all. They do work, so that means that there are periods per cycle that vary in intensity, and it's well defined, if not sharp. I don't expect it to be sharp either, because phosphor has persistence, which means it will continue to glow for a time after all excitation has ceased. This glow is at a much lower level though, and light coming from the phosphor will decay to this level fairly quickly, fast enough that the 120 bright periods per second are interspersed with 120 darker periods per second.

Flicker does exist. In the case of fluorescent tubes, it's both light output-wise and electromagnetic-wise. You're standing under an electromagnet where the current flow is zapping on and off constantly. That's the buzz you hear on top of the hum. To what extent it affects people I can't say, except for myself. Sometimes I'm bothered by fluorescent lights, sometimes not. If I'm tired or ill, it's worse. It's not just the cool whites, my combo warm and dayglo does that to me sometimes as well. I have not had that with the cfs.

I think it's quite possible that a person's brain trains itself to subjectively even out those pulses of light (basically ignores it) because it can, and when you're ailing your 'powers' are lower and then maybe it bothers.

What's always been the case is that it's difficult to pin down an exact cause of a discomfort or actual illness much of the time. There are too many factors. To say that it's these standard fluorescents that are giving me a headache may be partially jumping to a conclusion, but to say that this phenomenon doesn't happen is also jumping to a conclusion without sufficient evidence. This type of evidence is very hard to gather, if not impossible.

I'm no miracle medical man of galactic repute, so take what I'm saying as just my experience mixed with some experimental data gathered without an air-tight study process, mixed with objectivity and some conjecture- even some rationality.

As far as Willys headaches, he'll have to pin down whether the lights in the shop are affecting him, or what other factors are also possibilities. There are so many bugs these days, so many ways of contracting them, so many people spreading them, etc- around here it seems there's never a time when there isn't something going around.

Do you like to go for coffee, maybe read the newspaper? There's a sure-fire way to pick up some bugs. I went to McDonalds tonite ( I know, HORK, RETCH, etc) - the girl who drew my drink had moments before taken my cash, plus cash from other people, then with the same hand put two fingers inside my cup while taking it to the coke machine. Ever see them at Tim Hortons take a bare hand (after handling cash and all the keys on the machine) and shove it into your bag to open it, then take a waxed paper to pick up your dognut and carefully drop it in the bag without touching it? Ever see a waitress carry somebody's finished plate away with a bare hand, then pick up your cup by the rim to top you up- how many opportunities can you find to pick up germs- doorknobs, tap handles, fridge handles (a good source right there) - it has been said that the steering wheel is a breeding ground for germs. Got kids in school- it's likely that in many cases, a headache is the only symptom that your body is fighting something. Headache goes away, great. You might not be thinking that a bug had invaded you, cause your body fought it off and then you feel ok again.

Sometimes I think wouldn't it be good if you could see all those potential germs in the air, good or bad- maybe color coded to distinguish them- but then I think, no way, there's be nowhere you could go, except nuts.

Other factors for headaches- I used to have headaches all the time as a teen and pre-teen. I learned to make them go away by envisioning my blood pressure going to my hands rather than my head. A couple months ago a friend told me, out of the blue, that he had been using that technique that I taught him decades ago, and that it still works for him. I don't often get that kind of headache anymore, but when I do it still works for me.

Paul Alciatore
02-04-2008, 03:30 AM
I also have to question the validity of the tests on this one. Often the people making such tests are not properly trained in the scientific method and they have a cause that they want to support.

If you are bothered by fluorescent lights and think it is the flicker, ask yourself if you have any problems with CRT television viewing. It has the same light producing mechanism, exciting phospors and it does it at the same frequency, twice the line frequency or 120 Hertz in the US. If you can view TV for hours with no ill effects, then I doubt that the flicker is bothering you.

I also doubt it is any electromagnetic field effect. We are totally bombarded with EM fields in this day and age and fluroescent lights are probably a VERY minor contributor.

I would first tend to suspect either the color temperature or the sonic emissions that cheap ballasts and/or tubes are prone to make. Many people are quite sensitive to high frequency sounds.

As for the DC thing, before you think there is a difference, check the regulation or filtering of the DC being used. It is common to call rectified but unfiltered AC, direct current. More correctly, it should be called pulsating DC. If it is not filtered then it will have the exact same effect on flicker as the original AC current would. In fact, every DC power supply that operates from the AC line has some AC component remaining in it's output. The better ones have less, but it is there. Check out the specs on several and you will see. Look for AC ripple or 60/120 Hertz component.

02-04-2008, 06:17 AM
Hi All,
Just my 2 cents... One radio station I was Chief Engineer at had the exact same problems with florescent lighting and headaches. They remodeled the basement for the sales department and had installed 4 tube 4 foot fixtures for lighting. About 2 weeks after the sales dept. moved into their new digs most of the sales people started complaining of headaches. Engineering (me :rolleyes: ) was tasked with fixing the problem... Long story short, no chemical or aerosol problems. Someone mentioned lights so I checked, they had installed CHEEP cool white 40's in all the fixtures so I replaced them with Warm Whites as recommended (as I remember about 200 tubes). Now the complaint is that it is not as much light and everything is pink, told them to give it a week and we would see how things were going. One week later, NO headaches, bright enough to work in and the pink problem wasn't even mentioned :p .
So I think it is the harshness of the Cool White lights not the flicker. And some people are more prone to the problem than others. In my above story only about 75% of the people had problems and 2 or 3 had to leave the area or they could not work through the day the problem was so bad for them.

Try Warm White lamps :)

Good Luck,

J Tiers
02-04-2008, 09:14 AM
Darryl, I am well aware of the slight variation in intensity, as I mentioned re the slight strobe effect.

However, there are some modifying factors.....

One, the flash rate is 120Hz. That is substantially higher frequency than the eye's inherent "integration time".

two, the intensity does NOT reach zero at any time, so the "ripple" is just that, a variation, or "modulation" and not a flashing. it is not a "100%" modulation.

three, the character of the variation is not a sharp edged "square wave", but a semi-sine wave.

You may recall that a "movie" has a frame rate of about 1/5 that frequency.

And, the light is not present during the frame change, it is actually dark. Therefore there is a 100% modulation.

if in fact a person is sensitive to flashing lights, they should be totally unable to tolerate viewing a movie with the much higher percentage change,m and slower rate closer to the eye's integration time.

I myself am quite sensitive to fluorescent lights, which give ME a headache. However, it is evidently 100% due to the bright blue color of the "cool white" tubes. I can easily avoid the issue by adding some "warm white" tubes in the mix.

As a side issue, the only reason one can see the "dotted line" by swinging vision is that you use different areas of the eye for each dot. If the light is always hitting the same detectors, the 'dots" fuse into one continuous image.

Good point about CF bulbs. The filter capacitor in them may have a significant sag during one half cycle (often only 22 uF, they ARE made cheap), and there may be a strobe effect still visible due to it. I will have to try that.

it is not much realized, but a slight strobe effect even exists with incandescent bulbs. It is sometimes possible to see a strobe effect if you look carefully, depending on the bulb.

john hobdeclipe
02-04-2008, 01:06 PM
Just keep changing the lights around. You'll find yourself working harder and being more productive with each change. It's the "Hawthorne Effect."



Such a load of rubbish.

02-04-2008, 10:58 PM
I just hung some T12 bulb shop lights. One of the bulbs in one of the fixtures doesn't light. I purchased them new in 2001, but didn't get a chance to install until last week. Other electronic fluorescent lights I have failed "totally", not just a "half start warming" glow of one bulb. The other lights pluged into the same outlet operate normally, checked the wiring inside and it seems "ok/correct". The air temp, is approximately 65*F, but all the other lights, electronic and the older style, start and operate normally.

Does this sound like a replacement ballast is needed, or did I miss something?

02-05-2008, 05:17 PM
When electronics go they go completely. No light. I have change hundreds to thousands (Used to be a lighting tech). Your not putting t12's in the fixtures with electronic ballasts are you? There are very few electronic ballasts that support T12s.

In my garage I have a wide assortment of fixtures hanging:
2 - 175 MH low bay
1 - 150 watt MH
1 - 70w MH
1 - 8' 2L HO Fluor Fixture
1 - 4' 2L HO
1 - 4' 2L fixture.

I like light!

02-05-2008, 06:01 PM

I don't think so. I purchased three of these fixtures, two work where ever I plug them in, the third doesn't light one bulb (the bulb will light in the other two fixtures). This one was "bad" from the first go, so I think the manufacture's QC missed one, or it may be a ground problem.

In the wood shop (unheated/above ground with daylight), I have the five T8 (each four 48" bulbs) in a 12x14 feet area, plus hanging shop lights (T12/twin 48"), and too numerous to count "task lights". I haven't finished "illuminating" the metal shop, it is located in an underground bunker (literarily).

02-06-2008, 04:23 AM
Coming off the ballast will be 5 wires (assuming instant start ballast.) power is black/white, common lamp is red and there should be two blues, one for each end. Check the common connection at the tombstones. Sometime the jumper wire comes loose from the tombstone. Also check the other end as well. Of all the ballasts I have changed I cant remember any that were partially out.

03-06-2008, 10:09 PM
And in that time, another one of these "shop light" fixtures went "south". The ballast says "NAFTA BALLAST" and it puked it guts. I think the lights were bad from the factory. Hello 48 inch T8 quads, just like Studio G.

03-06-2008, 11:41 PM
I have 8-2 bulb fluorescent fixtures in the ceiling at my place and got occasional headaches. I put mag base work lights with an incandescent bulb on my machines to fill in and haven't looked back, it really helped me. (and I can point them where I need that little extra light)

tony ennis
03-07-2008, 12:22 AM
The only time I am sure fluorescents are bad is when using a monitor at the default frequency of 60 Hz. And I prefer warmer bulbs.

03-07-2008, 09:06 PM
if you are changing out the ballasts to new electronic, use the wiring diagram old style is series, new is parallel, there is a schematic on the ballast. I also thought the ballast ran more at 400hz?

03-07-2008, 10:06 PM
After all the reading here I have done about cf lights there is still 1 question I never find the answer too. Since cf lights use less power and are cooler does that mean I can now put the equivelent of a 100w bulb in a 40w fixture? Just how much " bigger" more light cf bulbs can safely be used? Many of the indoor light fixtures for homes say "60w max". 60 watt bulbs seem weaker all the time. What say you all?


03-07-2008, 10:44 PM
60 watts of current is 60 watts of current, independent of the lumen output. If the CF draws the same or less than the fixture is rated for, I don't see how there could be a problem.

03-08-2008, 12:03 AM
mark61 The twisted flourescent lights draw 13 watts and give off the equivalent of 60watts incandesient. So in that case you could put 4 twisted together and draw 52 watts. But the startup draw is probally alot more untill the bulbs warm up, which is about 5 mins. If you want to do that, why not go with LEDs? They draw ALOT less than flourescents and last longer and dont have to warm up........

03-08-2008, 02:24 AM
You can easily get away with a 100 w cf in a 40 w fixture. The rating is for heat build-up in the fixture, and the cf will dissipate much less heat. At the same time though, a cf device is electronic, and so it would be best if it didn't have to get too hot. I haven't had any problems with them overheating, and at 21 watts (for the 100 w equivalent) there shouldn't be any problem at all.

They do draw a surge current when first powered, but that is to charge the filter capacitor, which is a done deal after a fraction of a second. After that point, the cf is drawing a more or less constant current regardless of how bright it starts out at, or gets to be. There is probably a small variation, but nothing significant. It may take 5 mins for it to reach full brightness, but the amount of power it's drawing is pretty much constant.

The surge current issue is one which I wonder about in terms of the switch contacts. A normal incandescent bulb of 60 watts will draw 10 amps at startup if the switch is turned on at the moment when the ac voltage is going through its peak. This is a worst case scenario but it does happen. That's usually when the bulb fails as you flick it on, by the way. At any rate, that's the maximum current it can draw, and it drops very quickly to a half amp or so.

A capacitor on the other hand is basically a dead short to a rapidly changing voltage. When you first flick the switch, the cf draws a high current pulse because the main capacitor is charging up from zero. The instantaneous current pulse can be many times what an incandescent will draw at startup. It doesn't last long of course, but it makes me wonder how well a light switch can handle that.

I have a couple banks of four cfs, one that I plug in and one that's on a switch. Either one makes a pretty good snap sometimes as it's put on. I can't see that bothering a breaker or wiring, but for something rated at only 52 watts (4x60 watt equivalents) it sure does blip the other lights for a moment. In the ones I've had apart the rectifiers look to be the typical 1 amp type. Those are rated for a surge of about 70 amps for 8 milliseconds, and I wouldn't doubt that they pass a surge nearing this many times during the life of the cf. It wouldn't surprise me to learn that this is one main reason they fail. You could probably extend the life of them by using an electronic switch that's zero-crossing- but then you've got another electronic device subject to failure.

Interesting- today we were installing some countertops, and doing our trimming in the garage. There were two lights in there, and they were hooked to a controller of some kind (to come on when daylight fades, possibly) For whatever reason both were flicking on and off about 5 times a second. One of them was a cf. I found that somewhat amusing, wondering how long it would be before it fried.

J Tiers
03-08-2008, 11:02 AM
The tolerance of an incandescent bulb for heat is essentially unlimited. Certainly "unlimited" compared to most any socket etc.

A CF will tolerate very little heating. The solid-state components in it have typically NO heat dissipating assistance, and have a maximum temperature of around 150C. Due to the circuit design, it may not be possible to tolerate anywhere near that temperature.

And, that temp is down inside the closed-up bulb base, where cooling air usually cannot flow well, if at all.

If you want to do that, why not go with LEDs? They draw ALOT less than flourescents and last longer and dont have to warm up........

The LED lights are not a cure-all. The light is typically (IMO) a nasty color, but even then they are not always what they are claimed to be.

A recent article in "Electrical Wholesaling" (a trade mag for distributors) mentioned that under testing, many LED lights put out FAR LESS than claimed light output, and in many cases did not come close to claimed efficiency.

Many were far outclassed by CFs in terms of efficiency vs useful light output.

The quality of light issue was also mentioned.

Before you howl that the electrical industry is biased, remember that the target audience for the magazine just SELLS stuff. They don't make it, and have no vested interest in selling one vs another. They can sell LEDs. CFs, or whatever.

And, in fact, the mag has been touting the growing market for efficient lighting and recommending that distributors get on it and grow with it..

I have misplaced the article or I could reference the test lab involved.

03-09-2008, 01:33 AM
Well I just wanted to say "Thanks"

I have 8 lights w/2 bulbs each in my garage. I'm in it 99% of the time when its dark outside. I would always have a headach the next day. So I changed one bulb in each light with full spectrum bulbs, cost $36 at lowes. I havent had a headach in two weeks

Now if I could just get the raccoon out of the rafters..............