Knowledge You Can Build On — Est. 1998
Re: Question about the change
Jason Roehl in Lafayette, IN
The benefits:
Less decline in light output over time.
Lower power usage (probably less of a benefit in a home shop setting where it's used just a couple hours per day).
Jason
I'll change to LED for cold temp performance
Henry (Raleigh NC)
I haven't changed to LED but I will. Two factors lead me to this desire to change:
1. Flicker of fluorescent bulbs - more pronounced when cold
2. the slow start, and sometimes non-start, in cold temperatures (below 50 F?).
Performance most of the year is fine, but not in December or January (in Raleigh). I can heat the shop but don't necessarily.
Henry
Re: Question about the change
Don Goodwin
Bill, I have "upgraded" some of my t-8 fixtures with LED bulbs as the t-8's started to give me problems. My local ACE hardware sells a Westinghouse LED tube (~$15 ea., so about $30 per fixture) that eliminates the ballast. You get new tombstones and the instructions are to wire directly to 1 tombstone, bypassing the ballast. I removed the ballast as I re-wired. I'm not sure I saved any money in re-using the fixture, but I have an issue with throwing away a fixture that could be re-wired. I'm happy with the light - I think they are 5000k, don't know the lumens. They seem brighter than the t-8's that I still have.
Re: Question for LED shop light users
Bob Lang
Hi Bill,
I've got the Costco lights, here is the info from the box:
Mfr. Feit Electric
42 watts
4000 lumens
4000k cool white
I really like them for a number of reasons, most related to being frugal. There are two tubes in a fixture and it looks like a typical fluorescent four foot long shop light. The initial cost is between $20-30, depending on time of year. At the moment you (if you're a Costco member) you can buy two fixtures for $40. That tempts me to get a few more.
The fixture doesn't way much so it's easy for an old guy to hang and each fixture has a plug so you can string them together. My subjective impression of the output is that each is a little brighter and more pleasant than the typical fluorescent lights I've used previously.
Hope this helps,
Bob Lang
Re: Question about the change
Jim Dillon
What are the benefits? Long-lasting reliability, energy savings, directed light, no need for a replacement ballast (the "ballast" aka driver is built-in), rugged construction minimizing accidental overhead breakage etc. Plus, LEDs are so cool (literally and figuratively).
You must have magnetic ballasts.
Bill Tindall, E.Tn.
The electronic ballasts run at some number of KHz the eye can not follow, compared to magnetic at 60 HZ where many see as stress inducing flicker, myself included. In fact it is the flicker that set me to consulting with brother in law lighting engineer to see if the problem could be cured. I have electronic ballast fixtures in the lumber shed and they have never failed to start at least down to the 20 F range.
That said, the LED should in principle get brighter when cold.
grest....just what I needed....thanks
I have two types
Ian Neuhaus
One is a regular 4' long open bottom fluoro style tray fitted with 2 x T8 tubes. The box states:
3000 lumens, 18 W
colour temperature 4000 K = cool white
The other is a 4' long semi sealed unit with a lens. It's not clear if the light contains one or two tubes. The box states:
4000 lumens, 75 lumens per watt, 53 W (total)
Colour temp 4000 K = cool white
beam width 120 degrees -- this light seems to be more directional than the other one. side by side, the 4000 lumen light is the "better" one.
Bill, do you also want info on light intensity?
Ian Neuhaus
i.e. in your presentation are you intending to include info on what level of lighting is required in a shop and how to achieve it?
Info like how many lux (lumens per square meter) are required? See page 3 of this publication https://www.noao.edu/education/QLTkit/ACTIVITY_Documents/Safety/LightLevels_outdoor+indoor.pdf
if so, don't forget that older eyes need 50% more lux that under 40 eyes.
and lastly, how to arrange the lights to get the best illumination for your dollars
yes, your thoughts?
Bill Tindall, E.Tn.
"i.e. in your presentation are you intending to include info on what level of lighting is required in a shop and how to achieve it? "
This topic is of course the main focus of the presentation along with how to achieve this result.
Brother-in-law the lighting engineer suggested 200 foot candles for detailed tasks, and 20 f.c. background. Background is as important as light at task, he says. I find that just about right.
It took a boggling amount of 4' Tofers to get this level on my bench. The ceiling was literally covered with them. They all went away to be replaced by 2-T5HO units. Of course windows are best of all.
Task lights are a different solution but I dislike having to deal with them on the bench, and repointing them endlessly. Battery powered LED task lighting could be desirable but I have not investigated it thoroughly.
Maybe . . .
CJ in MPLS
In order to return light from an object of a particular wavelength, that particular wavelength needs to be available from the source. While fluorescent light might be more diffuse, it is more likely that the effect that you observed is due to the fact that those bulbs emit a spectrum that is complementary with the materials being illuminated. In other words, there is red light for rubies, blue light for sapphires, etc. LED's can be a bit more limited in their spectrum. Not saying this is always the case, but often it is.
Fluorescence in the objects being illuminated could always produce some light of different wavelengths, but it is unlikely to be significant. The excitation light is usually in the UV range and I suspect that fluorescent bulbs don't emit that much UV. I've never had a sunburn in my office, for example.
Re: Maybe . . .
John in NM
I don't think it was that, he sold stones of all colors and they all looked better under the fluorescent lights. The optics of color stones gets more complicated, because the more saturated they are, the better they end up looking when there is a certain amount of light coming through them from behind. The people selling diamonds were always using halogens and dark backgrounds - because glitter was the selling point, we were using fluorescent and white backgrounds to better show the color.
Spectral properties of light
Bill Tindall, E.Tn.
Picture 1 shows the light distribution of incandescent light(3000K line), light generated by anything hot like a filament. There is some light at all wavelengths but the light is biased red with very weak blue. Picture 2 shows the light distribution (spectrum) of a high quality fluorescent lamp with terbium and europium phosphors. If one of these spectral lines reflects back from the colored gem, colored because it absorbs certain wavelengths of white light, I can see where the appearance would be more intense than when viewed under incandescent light. Picture 3 compares various light sources.
In the case of diamond what is desirable is to reflect back white light, ideally from a point source like a halogen lamp.
Re: Spectral properties of light-difficulity!
Larry Clinton At Frankfort, (Central) Indiana
To actually determine the "color" of an object is quite difficult due to not only the light source illuminating the object but also human eye perception.
The company I retired from manufactured many items that mounted in the dash and console's of GM automobiles. Matching of the "color" of the items as well as applied graphics was imperative. We also provided back lighting of several switches, and lighting sources such as map lights etc.
In order to color match the company purchased a machine that measured light intensity and color, object color etc.. As I recall it cost near $100K, but was the only way to provide a non-subjective solution.
Several years ago I was responsible for developing a visual inspection system to inspect the graphics of a Prndl (Park, Reverse, Drive, Low) console gear box indicator system. This had to be inspected as near as possible in the actual lighting it would be viewed in the actual vehicle. At the time I found Halogen surface lighting was the best solution - possible a combo of led's with different characteristics would work today.
All true....
John in NM
But not the point I was trying to make.
I really don't care a great deal about the LED vs. fluorescent debate, but I do find the appeal of LED's in spite of measured lumen output to interesting. I think there is more going on than just the marketing hype working as it often does.
The point was that direct, contrasty, glittery light appears brighter to the mind. My example was just a case where I'd seen that illusion work contrary to a demonstrable result, where something actually looked better in the more diffuse (yet brighter) light.
In the case of LED shop lighting, I think people are probably reacting favorably to the directness of the lighting causing more shadow or something like that. Not only do the lamps appear brighter in spite of the measured output, the end result is desirable for the application - better contrast.
But this is all pretty speculative on my part.
