LED Lighting - 4' tubes best option? Change from reflective to direct?

[Doug Hobkirk]

Years ago I scored a pile (20? 30?) of high quality office fluorescent lighting fixtures. They only worked when pointed up, so I used ten 2-bulb fixtures for reflected light in my shop. I was too lazy to engineer flipping them over (they are suspended by a wire at each end). It's worked OK, but it was never great.

But time marches on: my eyes need more light, bulbs are dying, and LED tech has mostly arrived.

I am getting some LED lights that replace fluorescent tubes (http://www.amazon.com/gp/product/B012AHPPTQ?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00). They are directional. I will experiment with reflective, but I expect I will need to flip them over and have the light pointing directly down. Since the LED tubes don't require ballasts, the fixture is not very necessary - the "tombstone" ends could be mounted on any 4' long surface, the white reflective surface doesn't help (?) since the LEDs are directional, but the fixtures are at hand and offer some protection from my swinging boards around.

I am getting six bulbs to experiment with, two of which are for my office.

But maybe there are better solutions? Cheaper? Brighter? More usable?


Note 2 dead tubes! They just died. I think the tubes realized I was buying new ones...
327166 327167

Footnote on Existing Fixtures: 1-4 can be joined, they are suspended by one cable at each end. I found them handsome, so I balked at drilling holes into them. I could have suspended them flipped over if I'd had a 8" wide trapeze at each end, but that was just slightly beyond my patience level when I was doing this. I only used 9 or 10 in my shop, one in my office, and I have a bunch stored in the garage attic. I paid $30 for all of them, and I have yet to buy any new bulbs (I just grab them out of the stored units). Who is adding fluorescent lighting now? They don't have any value anymore.

[Greg R Bradley]

Lots of people are installing fluorescent lighting still. Many, many LED are less efficient than the better fluorescent lights. Another big problem is color rendition. LED is great for many things but color rendition is way behind. Are you going to finish woodworking projects? If so better forget about LED. LED with decent color rendition are all below the efficiency of florescent. LED with great color rendition are way below the best florescent. The actual reality is that there is NO one solution for all lighting problems.

In one furniture manufacturer, I have all florescent with various features on the bulbs of light output, long life, and color rendition. ONLY the warehouse and main shop area would be appropriate to convert to LED. The energy savings would be almost zero to do so. It only makes sense in a number of years as light bulbs wear out and ballasts start to fail.

Many of the inexpensive LED lamps designed to replace florescent are directional. This can be an advantage in some situations but can be a big disadvantage in others. With lots of different fixtures in lots of different situations in lots of different businesses, I can say that has been a problem far more often that an advantage. I'm in the middle of trying to get the first of one manufacturer's 360 degree light output T-12 replacements right now to solve one of those problems. There are a few wide dispersal LED tube replacements that claim 240 degree output that do help solve some issues. When someone starts saying that all LEDs are "better" because they shine the light down, just realize they are trying to sell their product, not a solution to your problems.

The nonsense in the link you provided is salesmanship, not facts. A 22w LED T-8 replacement is way better than a worn out and dirty 32w T-8 fluorescent. Comparing a 22w LED as "75w equivalent" is about the same as old time additives that gave your car twice the miles per gallon, actually far worse than that claim. Compare it to a new high end T-8 fluorescent and it may be better and may be worse depending on the specific application. What most people forget is that there are good fluorescent bulbs and cheap junk and they all need to be replaced far before they actually start failing. People just want to believe that LED is somehow magically better but it just doesn't match reality.

[Brian Hood]

Years ago I scored a pile (20? 30?) of high quality office fluorescent lighting fixtures. They only worked when pointed up, so I used ten 2-bulb fixtures for reflected light in my shop. I was too lazy to engineer flipping them over (they are suspended by a wire at each end). It's worked OK, but it was never great.

But time marches on: my eyes need more light, bulbs are dying, and LED tech has mostly arrived.

I am getting some LED lights that replace fluorescent tubes (http://www.amazon.com/gp/product/B012AHPPTQ?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00). They are directional. I will experiment with reflective, but I expect I will need to flip them over and have the light pointing directly down. Since the LED tubes don't require ballasts, the fixture is not very necessary - the "tombstone" ends could be mounted on any 4' long surface, the white reflective surface doesn't help (?) since the LEDs are directional, but the fixtures are at hand and offer some protection from my swinging boards around.



Footnote on Existing Fixtures: 1-4 can be joined, they are suspended by one cable at each end. I found them handsome, so I balked at drilling holes into them. I could have suspended them flipped over if I'd had a 8" wide trapeze at each end, but that was just slightly beyond my patience level when I was doing this. I only used 9 or 10 in my shop, one in my office, and I have a bunch stored in the garage attic. I paid $30 for all of them, and I have yet to buy any new bulbs (I just grab them out of the stored units). Who is adding fluorescent lighting now? They don't have any value anymore.

Hi Doug,
LED's these days approach 100 lumens/watt, so at best the 22 watt lamps will throw off 2,000 lumens (but probably not), where a T8 fluorescent will produce 3,000 lumens, and very often much more. At this point replacement lamps for fluorescent fixtures does not often pencil, or work.

You don't really say in your post what you are trying to achieve. If you want really good light from an LED source I would go with Pixie LED panels, make sure they are the 4000K version (so Amazon and not Home Depot).
If you want a lot more light you have to flip those fixtures over, they are direct/indirect with a 20/80 or 30/70 distribution.

[Frank Pratt]

Hi Doug,
LED's these days approach 100 lumens/watt, so at best the 22 watt lamps will throw off 2,000 lumens (but probably not), where a T8 fluorescent will produce 3,000 lumens, and very often much more. At this point replacement lamps for fluorescent fixtures does not often pencil, or work.

You don't really say in your post what you are trying to achieve. If you want really good light from an LED source I would go with Pixie LED panels, make sure they are the 4000K version (so Amazon and not Home Depot).
If you want a lot more light you have to flip those fixtures over, they are direct/indirect with a 20/80 or 30/70 distribution.

But with LEDs, all 2000 of those lumens will go where you want them. With fluorescent, a lot light is wasted in the optics. Watt for watt, quality LEDs will give much more light. We've installed lots of LED fixtures & that is our experience.

That being said, fluorescent still is by far the best value buck for buck. And if you care about the quality of the light (and you should) fluorescent is better still. LEDs with a CRI over 90 is very expensive. Fluorescent is available with a CRI of 98, but those are not your standard big box items.

The cheap LED fixtures sold by Walmart, Costco etc are only about 80 CRI, which is pretty poor light

[Doug Hobkirk]

Hi Doug,
...You don't really say in your post what you are trying to achieve. If you want really good light from an LED source I would go with Pixie LED panels, make sure they are the 4000K version (so Amazon and not Home Depot).
If you want a lot more light you have to flip those fixtures over, they are direct/indirect with a 20/80 or 30/70 distribution.

My goal = better light on my work surfaces + spend little + save on utility bills (the normal, right?)

Is this is the correct panel (http://www.amazon.com/LEDwholesalers-40-Watt-Edge-Lit-Glare-Free-2104WH/dp/B00776HLRU/ref=sr_1_1?ie=UTF8&qid=1450221636&sr=8-1&keywords=pixi+4000k+led)you are talking about?
* Power: 40W
* Available Color Temperatures: White 5000-6500K | Neutral White 4000-4500K | Warm White 3000-3400K
* Light Output (lumen): 3500 | 3300 | 3100
* Beam Angle: 120º
Amazon doesn't list options, just one number. Is color termperature settable in the light itself?


But with LEDs, all 2000 of those lumens will go where you want them. With fluorescent, a lot light is wasted in the optics. Watt for watt, quality LEDs will give much more light. We've installed lots of LED fixtures & that is our experience.

That being said, fluorescent still is by far the best value buck for buck. And if you care about the quality of the light (and you should) fluorescent is better still. LEDs with a CRI over 90 is very expensive. Fluorescent is available with a CRI of 98, but those are not your standard big box items.

The cheap LED fixtures sold by Walmart, Costco etc are only about 80 CRI, which is pretty poor light

Excellent point. I could not find the CRI measurement - MFG Website (http://www.kedsum.com/index.php?m=content&c=index&a=show&catid=461&id=72).


...In one furniture manufacturer, I have all florescent with various features on the bulbs of light output, long life, and color rendition. ONLY the warehouse and main shop area would be appropriate to convert to LED. The energy savings would be almost zero to do so. It only makes sense in a number of years as light bulbs wear out and ballasts start to fail....People just want to believe that LED is somehow magically better but it just doesn't match reality.

You intimidate me Greg! But your information is very helpful.

I know there's no perfect answer or "free lunch." I need to upgrade my lighting and I decided to ask the experts. Which you are. You have not caused me to cancel my order for those T8 LED tubes, but I will certainly examine the results better thanks to your comments.

Thank you all very much.

[Ole Anderson]

I have installed two of the HD 4 foot LED shop fixtures at $40 each. 80 CRI but I am not picking a paint color to match my wife's curtains. 4000 k color temp, real happy with that. 3200 lumens, 36 watts, 50k hours. Absolutely silent, instant on. How much would I have to spend to get a fluorescent fixture and bulbs to better that? I am very happy with them and will eventually use 3 more to replace failing 4' shop fixtures. I do have an 8 footer with new bulbs that will stay put, even if it is noisy. http://www.homedepot.com/p/Commercial-Electric-4-ft-LED-Linkable-White-Shop-Light-54103161/205331022

I believe fluorescent will go the way of the carburetor eventually. Already they are starting to take over the CFL market. I just put 3 equiv 100 watters in my garage replacing CFL's which are an issue in lower temps here in Michigan winters. All the new street lights going in now are LED.

[Mike Chalmers]

While I do not have the knowledge to fully understand all of the information presented above, I do have some actual experience to rely on. My shop was lit with typical 4', dual tube, T12 fixtures. One of the ballast resistors went, and I replaced that fixture with a 4' LED fixture. Cost @ $159. (Home Depot Canada)

I recently stumbled across a clearance at the same Home Depot of LED direct replacement bulbs for fixtures with electronic ballasts. I replaced 8 bulbs (4 fixtures).

Result? Fantastic! Lots of light, blemishes in my sanding job easily detected. I do not notice any detriment to colour. That being said, I still have three T12 fixtures in the mix.

[Brian Hood]

Hi Frank,
DOE's Caliper program runs labs testing these ideas and the last report recognized your points and stated that the fluorescent fixtures delivered more light. The thing about those tests is the LED's keep getting better and cheaper so last years test doesn't mean it's the true state of affairs.
Light Quality- we, my firm of four full time lighting designers, are mainly concerned with lighting art, art collections, and the houses built around those collections. We specify and adjust after installation many hundreds of Halogen and LED lamps and fixtures- we don't use any fluorescent any more. I personally can't see 95CRI or 97CRI as 'better' than 84CRI, and sometimes on some objects the 84CRI looks better. What we've seen is that the shift the common 84CRI fluorescent tube makes is less pleasing to clients than the color shift that 84CRI LED's make, they like the LED's and don't want the fluorescents. I don't mind decent fluorescents but I do prefer the LED light to the extent I've replaced my Garage fixtures with them and will do the shop next.
Agree totally that from a value proposition fluorescents are still the way to go unless there has been some developement in the last few weeks we don't know about.

[Brian Hood]

Doug,
we don't like the 1/2" think panels that then have a giant box sticking out of the back of them- check out photo #2 on the Amazon link. Might work for you, though. We pefer, I am installing, http://tinyurl.com/jchyl4r

Color temp of a single LED can't be changed in any case I know of, but it is possible to put different color LEDs in the fixture and blend them to create colors. That is not happening with the fixture you link to.

I am looking forward to your experiences with your new lights. You might consider flipping the fixtures over however you go, although those fixtures you have don't look all that great from the other side.

Many times you can get 10 to 20% more light from a fluorescent lamp by cleaning it- Dirt Depreciation is a factor we are supposed to build into the lighting calcs. It makes a difference.

[Allan Speers]

Lots of people are installing fluorescent lighting still. Many, many LED are less efficient than the better fluorescent lights. Another big problem is color rendition. LED is great for many things but color rendition is way behind. Are you going to finish woodworking projects? If so better forget about LED. LED with decent color rendition are all below the efficiency of florescent.


I recently purchased a bunch of mr16 LED bulbs at 5700K, with an 85 CRI rating. That's pretty good. I like them better than my old "daylight" flourescents, though I don't know what the old tubes were rated at.

As for efficiency, I was just looking at some new Magnitude LED drivers (trannies) 12vdc output - and they are only rated at 80% efficiency, so that's a good point. At the same time, these 4 watt bulbs, supposedly equivalent to a 20w halogen, actually seem about as bright as my old 35w halogens, so it may even out.

[Allan Speers]

Now, if you want your head to explode, start researching how to make the bloody things DIM. :eek:

This is one of the most complex, arcane, and infuriating topics I've ever had to research. Been at it for over a week, and I've decided to just give up and wait for the technological changes to slow down.

[Greg R Bradley]

Wait for technology to slow down? I don't think that is going to work out.

One of the few places that I think I really gained something with LED conversions is the ability to wire 2 circuits into the same fixture that originally had one ballast. Previously if you wanted less light, you had to turn on half the fixtures, now I can turn on half the bulbs in each fixture.

I have a bunch of near identical offices used for various functions. Each office is 12x12 with 4 surface mount wrap-style fluorescent fixtures. Previously one switch turned on two and another switch turned on the other two. By converting to direct wire LED, I obtained the best functionality by wiring one switch to turn on one bulb in each fixture and the other switch to turn on the other bulb in each fixture. The new way lets you run half the lighting far more often. Of course I benefit from a wall of floor to ceiling windows facing south in SoCal.

Because I have so many similar offices, I spent a lot of time on this so that the others can be duplicated. The original lamps are 2 4' 40w T-12 lamps. One office had been converted to T-8 lamps so was also used as a test. Not quite as good as seeing the lights side by side but darn close.

I bought 2 of each the 13 different LED replacement I could find to try out. I also bought a new Lithonia LED fixture replacement that is basically the same fixture built from scratch as an LED fixture. Readily available from HD: http://www.homedepot.com/p/Lithonia-Lighting-4-ft-Flushmount-Ceiling-White-LED-Wraparound-Light-LBL-4/203839057

It quickly became obvious that none of the replacement bulbs match their claims. It was interesting that the new LED fixture in real life worked almost exactly like the 40 year old fixtures with new LED bulbs. I have two comments about replacing the fixtures instead of removing ballasts, rewiring, and installing direct feed LEDs. A positive is that they are accurately rated as far as light output, current draw, and efficiency as opposed to the upgrade bulbs that all lie about their ratings, some to an outrageous degree. A negative is that they are rated for 50,000 hours at which point the fixture needs to be replaced. Under our use, the would last less than 15 years and we have already been using those fixtures for 35 years.

If you are curious, the LEDi2 22w was everyone's favorite but the Luceco 24w was very close and half the price. The clear winner in usable light per watt was the Sunsun 18w that has 360 degree output. Doing fine work under it was better than any of the other 18w or 19w bulbs and very close to the LEDi2 22w. The three direct replacement lights that connect without removing the ballast were definitely a waste of time and money and reminded me when people tried replacing 32w T-8 tubes with 25w tubes.

I ended up with the Sunsun 18w on the inside 4 bulbs in the center of the room and the LEDi2 22w in the 4 outside toward the outside walls. I think if Sunsun made a 22w version, we might get close enough to a new high quality 40w T-12 or 32w T-8 that nobody would notice the difference. Since florescent lose light with age, I'm sure there would be no actual difference after a few years of use. If you try what most people do and not clean the fixtures and replace the bulbs until they actually fail, then the LED will be way ahead at that point.

Of course, most of the LED seemed to be an improvement when compared to the dirty units with old bulbs. The single huge improvement was the single fixture in each office that was completely cleaned and given a new T-12 or T-8 bulb of high quality. The biggest energy savings will be the ability to rewire and run one bulb in each of the four fixtures during the brightest part of the day.

[Brian Hood]

Now, if you want your head to explode, start researching how to make the bloody things DIM. :eek:

This is one of the most complex, arcane, and infuriating topics I've ever had to research. Been at it for over a week, and I've decided to just give up and wait for the technological changes to slow down.

Hi Allan,
problem isn't the tech, it's the variables in your set-up.
Variables:
A. The transformer, because you are converting primary voltage to low voltage. Those are 12 volt lamps.
B. The driver. In the base of each of your lamps is a tiny circuit that converts the 12 volts to the final voltage the LED will use to push the electrons through the PN junction, probably 5.5 volts DC.
C. The dimmer.
In order to dim an LED you have to ensure that each of those variables are designed to dim, and designed to work with the other two variables (components). In some cases, for example the Pixie panel I like, you connect it to most any old dimmer and it dims great. In other cases dimming just can't happen. So first you need to determine if the lamps are dimmable, at all. Then look to the transformer, using a magnetic transformer (old tech, heavy, just wire wrapped around an iron core) is the simple way to get to compatabilty. Finnaly use a magnetic low voltage rated dimmer and you might be good to go.
Brian(J)

[Bill Adamsen]

I have a combination of LED and Florescent in the shop. LED of course seems to be the wave of the future if not the present. In my situation, I use the LED for primarily ambient light when I need or want to keep the shop lit and save money. The wattage consumption is ridiculously small compared to incandescent.

For primary lighting I installed rather pricey ($140+/- per fixture) "greenhouse style" T5HO fixtures ... four and six lamp ... made in huge quantities for growing you know what. They are mounted between 10 and 12 feet high. I carefully selected the bulbs for temperature and CRI, and am immensely pleased with the result. The light is extraordinary ... fantastic for all tasks in the shop. I never thought florescent could work so well. Everyone that enters the shop comments positively on the amount and quality of illumination. I know this doesn't answer your question specifically but it might still be an alternative.

[Frank Pratt]

I have a combination of LED and Florescent in the shop. LED of course seems to be the wave of the future if not the present. In my situation, I use the LED for primarily ambient light when I need or want to keep the shop lit and save money. The wattage consumption is ridiculously small compared to incandescent.

For primary lighting I installed rather pricey ($140+/- per fixture) "greenhouse style" T5HO fixtures ... four and six lamp ... made in huge quantities for growing you know what. They are mounted between 10 and 12 feet high. I carefully selected the bulbs for temperature and CRI, and am immensely pleased with the result. The light is extraordinary ... fantastic for all tasks in the shop. I never thought florescent could work so well. Everyone that enters the shop comments positively on the amount and quality of illumination. I know this doesn't answer your question specifically but it might still be an alternative.

T5s are a great light source. Love your shop.

[Brian Hood]

I carefully selected the bulbs for temperature and CRI, and am immensely pleased with the result..

You have every right to be immensely pleased, many of us are immensely envious right about now.
Curious what CRI/Temp you ended up with.

[Doug Hobkirk]

I have a combination of LED and Florescent in the shop. LED of course seems to be the wave of the future if not the present. In my situation, I use the LED for primarily ambient light when I need or want to keep the shop lit and save money. The wattage consumption is ridiculously small compared to incandescent.

For primary lighting I installed rather pricey ($140+/- per fixture) "greenhouse style" T5HO fixtures ... four and six lamp ... made in huge quantities for growing you know what. They are mounted between 10 and 12 feet high. I carefully selected the bulbs for temperature and CRI, and am immensely pleased with the result. The light is extraordinary ... fantastic for all tasks in the shop. I never thought florescent could work so well. Everyone that enters the shop comments positively on the amount and quality of illumination. I know this doesn't answer your question specifically but it might still be an alternative.

Like Brian, I'd love to read more details. I have low ceilings, so I couldn't use the exact same fixtures, but I am curious about temperature and CRI details.

[Greg R Bradley]

A 4 lamp T5HO fixture is functionally almost identical to a 6 lamp T-8 fixture. A tiny bit more power draw and a tiny bit more light coming out from a smaller area so they need to be mounted a bit higher. Both would work great in the high mountings shown in his shop. Both are high bay fixtures and are horribly glaring if not mounted high. The disadvantage of T-5 fixtures is that they are not convertible to LED anything at some point down the road since they are a shorter metric length and not 48" fixtures. NO efficiency advantage of T-5 over T-8 but they were able to make lamps with no mercury in T-5 at the time they were invented and it took a few years before they accomplished that in T-8. Pretty much a solution to a problem that no longer exists unless you are a pot farmer.

General rule is 6 lamp T-8 should be a minimum of 12' high and 4 lamp T-5HO should be at least 14'.

[Allan Speers]

Hi Allan,
problem isn't the tech, it's the variables in your set-up.
Variables:
A. The transformer, because you are converting primary voltage to low voltage. Those are 12 volt lamps.
B. The driver. In the base of each of your lamps is a tiny circuit that converts the 12 volts to the final voltage the LED will use to push the electrons through the PN junction, probably 5.5 volts DC.
C. The dimmer.
In order to dim an LED you have to ensure that each of those variables are designed to dim, and designed to work with the other two variables (components). In some cases, for example the Pixie panel I like, you connect it to most any old dimmer and it dims great. In other cases dimming just can't happen. So first you need to determine if the lamps are dimmable, at all. Then look to the transformer, using a magnetic transformer (old tech, heavy, just wire wrapped around an iron core) is the simple way to get to compatabilty. Finnaly use a magnetic low voltage rated dimmer and you might be good to go.
Brian(J)

Nope, there's a LOT more to it.

Magnetic vs electronic (leading edge vs trailing edge) dimmers
Magnetic vs electronic drivers
12vav vs 12vdc.
- Some bulbs can use both, some cannot, and this information is NOT EVEN LISTED AS A SPEC. - And none of the retailers I talked to had a clue about any of the bulbs they were selling.


I've been on the phone with techs from Magnitude, Luxtron, Solaris, GE, etc for days & days.

Some of the best drivers don't play nice with the best dimmers.

Some combinations of dimmer & driver give a nice range of brightness, others barely dim by 10%.
Some combinations simply don't work at all.

Luxtron claims ELV is by far the best. magnitude claims that MLV is by far the best
One bulb manufacturers claims that X is the best dimmer, Another bulb manufacturer claims that X doesn't dim well at all.

Then there's the efficiency conundrum, as various combinations change the percentage.

Oh, then there's that business with using neutral as a reference. ELV does (seems like a good thing) MLV doesn't. - Except when it does.

And finally, there's the buzzing issue. (I own & operate a recording / post studio, so this is important.)
- There's both mechanical buzzing which happens with some bulbs (no one has yet made a list of which are bad & which are good) and buzzing caused by EMI from the dimmers. Well, ELV dimmers should theoretically give off less EMI than magnetic, but MLV supposedly (depending on who you ask) can minimize the mechanical bussing.



And so forth ........ It's worse than asking what's the best way to design a DC system. :mad:

[Brian Hood]

Nope, there's a LOT more to it.

Magnetic vs electronic (leading edge vs trailing edge) dimmers
Magnetic vs electronic drivers
12vav vs 12vdc.
- Some bulbs can use both, some cannot, and this information is NOT EVEN LISTED AS A SPEC. - And none of the retailers I talked to had a clue about any of the bulbs they were selling.



Some combinations of dimmer & driver give a nice range of brightness, others barely dim by 10%.
Some combinations simply don't work at all.


Oh, then there's that business with using neutral as a reference. ELV does (seems like a good thing) MLV doesn't. - Except when it does.

And finally, there's the buzzing issue. (I own & operate a recording / post studio, so this is important.)
- There's both mechanical buzzing which happens with some bulbs (no one has yet made a list of which are bad & which are good) and buzzing caused by EMI from the dimmers. Well, ELV dimmers should theoretically give off less EMI than magnetic, but MLV supposedly (depending on who you ask) can minimize the mechanical bussing.


:mad:

Hi Allen,
I was not trying to say that dimming replacement lamp LEDs is easy, I was pointing out that solving the problem involves changing the variables. You seem to be agreeing with me as you list the variables very well.
In my work, every day I have to specify LED lighting that dims well. The solution with replacement lamps has been to experiment endlessly with the different combinations and to that end I have a good size room filled with lamps, dimmers, fixtures, etc. I believe that coming up with one definitive answer to all dimming of LEDs in all fixtures is impossible, but that individual solutions can be found.
From this real-world experience, in my evolving opinion, magnetic transformers will be successful much more often than electronic, but at a lower performance and often with some buzzing. (Juno brand fixtures buzz most of the time for some reason, we can't use them.) An electronic transformer tuned to the lamp and dimmer can usually achieve the highest performance. Right now, the Fulham Pony series ELV transformers are working for us better than any other.
Recording studios- I could never find a wave-chopping (triac based) dimmer that did not make more noise than was acceptable, in the old days we had to use a variable autotransformer and sometimes a choke coil to get completely silent dimming. Today, I would try dedicated LED fixtures with on-board 0-10 volt dimming built into the driver, in effect eliminating all of the variables. In the future lighting control will be very different, light fixtures will have unswitched power run to them and receive dimming instructions wirelessly from the dimmer switches in whatever combination you like. Inside these fixtures the dimming will be PWM and it will work great. This can be done today with Lutron stuff you buy from Amazon, it just hasn't caught on yet.

[Brian Hood]

Greg, your experience with fluorescent lighting is much greater than mine, thanks for your input. Your comments match exactly what we've observed, T5HO is way too bright unless mitigated by distance, baffles, lenses, or reflecting it off something.

In a previous post you mentioned extensive testing to LED replacement 4' tubes. I wonder if you tried this:
Philips 434886 InstantFit 32 Watt Equivalent 4-Foot T8 LED Tube 4000K

I've only seen the DOE lab test results but they seemed pretty great.

[QUOTE=Greg R Bradley;2504937]A 4 lamp T5HO fixture is functionally almost identical to a 6 lamp T-8 fixture. A tiny bit more power draw and a tiny bit more light coming out from a smaller area so they need to be mounted a bit higher. Both would work great in the high mountings shown in his shop. Both are high bay fixtures and are horribly glaring if not mounted high. The disadvantage of T-5 fixtures is that they are not convertible to LED anything at some point down the road since they are a shorter metric length and not 48" fixtures. NO efficiency advantage of T-5 over T-8 but they were able to make lamps with no mercury in T-5 at the time they were invented and it took a few years before they accomplished that in T-8. Pretty much a solution to a problem that no longer exists unless you are a pot farmer.

General rule is 6 lamp T-8 should be a minimum of 12' high and 4 lamp T-5HO should be at least 14'.

[Greg R Bradley]

No, I only tried two lamps that were to be used with the existing ballasts as virtually all the lamps in this batch were T-12, not T-8. I tried the Osram Sylvania Ultra 19w, which Lowes is stocking, and the Cree LEDT8R-48-40k.

If they can actually get 2000 lumens out of 16.5 watts, that would be really great. I also like that they are at least claiming 160* spread as the typical one are claiming 120* and the narrow angle just causes too much issue in most cases. Of course, the light spread doesn't actually work that way so who knows what is what. This diagram is from the LEDi2 that worked the best for us and they claim 240* spread:
327377