T5 vs. T8 fluorescent lights

As I mentioned here once before, try a couple of the GE kitchen and bath bulbs in one of the fixtures. You'll like it.

Reply to
Larry Blanchard
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The discussion of the use of T5/T8 5000 lights sparked my interest - as I had no idea what it was - and I've found tons of information on the internet about it. But as usual, weeding through the contradictions is always difficult.

Some people seem to view the T5 as superior to the T8, both in energy usage and in output. Then I've also found pages saying it isn't true.

A T5 seems very small to be that good at producing enough light ... but some people say they do in fact produce the same amount of ligth.

Who out there is using these and can you give me your opinion on which to go for? I have outlets in the ceiling out the gazoo ... so I can install as many of these as I need. My concern is that I get enough natural looking light, but without an UV since I burn easy.

Jack

Reply to
mywebaccts (at) PLUGcomcast.ne

Jack, I assure you the T5 will produce a great deal of light. I have hundreds of them installed in our dealerships and they are great. We are using them as a replacements for the Metal Halide fixtures with T5s as well as older T8s. I too am replacing the fixtures in my shop with T5's and really put out the light. I do not know about the UV levels but the T5 is the future of fluorescent lamps.

Dave

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Reply to
TeamCasa

Total light output depends on the phosphors and design of the tube. Different tubes vary as to color temperature and total light output. (Yes, even within families such as 4 foot T-8 and T-5.) HO and VHO bulbs increase light output, but at a loss of bulb life and higher energy consumption.

Look at the bulb specs. Standard T-8 and T-5 bulbs are very similar. There will be a rating of total lumens (after burn-in). Note also the wattage/current it consumes. The CRI is based upon a physiological rendering comparison of the color to noon daylight - the higher the better.

Extrapolate the lumens per watt for the selected bulbs. ~Efficiency. Find out which type is most affordable in your area. Buy based upon sound research.

UV burning isn't much of a factor with fluorescent lighting - perhaps with specialty actinic or UVa/b bulbs, but not std illumination bulbs. It is more of a concern with Metal Halides, especially if the outer envelope is damaged.

FWIW,

Greg G.

Reply to
Greg G

I'm actively researching lighting for my new shop right now.

I found a government report on ligghting and energy use. They actually say the T8 is more energy efficient than T5 in many applications. A popular energy saving application for T5 is the replacement of high bay lighting in factories and warehouses.

I found that 96" (actually 92" I believe) T5 fixtures cost about twice what 96" T8 fixtures. 96" T8 strip fixtures for two bulbs cost $58 to $65 or so. The only 96" T5 strip fixtures I could find were $121 each plus the bulbs are very expensive.

T8 96" bulbs are 59 watts and T5 96" watt bulbs are 54 watts. I am certainly not going to pay twice as much to save 10 watts per fixture. I could save about 10 cents every 100 hours the fixture is used.

If anyone has any insight on where to buy the F96T8 strip fixtures for two bulbs, I would appreciate it. So far, I know Grainger has them for about $63 each with no shipping. I am also going to try the electrical supply houses. Shipping on 96" fixtures isn't really worth it.

Brian Elfert

Reply to
Brian Elfert

RE: Subject

At one time in a past life I designed and sold a lot of lighting systems .

From that perspective, will off the following:

What you want to buy are lumens delivered on the surface you want to light.

By definition, one lumen per square foot = one foot candle.

What you pay for is KWH of electricity.

The lighting system converts KWH of electricity into lumens.

The more efficiently it does this process, the better the lighting system.

Trying to compare the inital cost of various componets is meaningless with out also including the cost of installation, annual hours of operation, efficiency of the lamps, cost of KWH, and the dirt factor of the space you want to light.

Not exactly a simple problem.

Ya pays your money, ya takes your pick.

Lew

Reply to
Lew Hodgett

Is there a formula to correct for the distance of the subject to the fixture?

It seems to me that low ceilings always need more lights. Or is it my imagination?

Thanks, Barry

Reply to
Ba r r y

Well, as long as we're on the subject of lighting, I'm gonna take a shot at butting in.

I'm also looking to light a shop (24 X 25 X 8' ceiling), and in reading an article on workshop lighting, it suggested 80-100 fc for old fogies (40+) like myself for a woodworking shop.

So, while I know there are probably 50 variables including the paint color, machines, etc., how do I (even ballpark) get from KWH (or wattage) to foot candles? Basically, after reading the article I know I want "lots of light," but I still have no clue how to convert "lots of light" into X-number of 2-bulb, 4' fixtures. Any suggestions on how to make the conversion?

Thanks,

Ricky

Reply to
Ricky Robbins

There are some, but frankly I never used them.

Good engineering and some basic SWAGs took care of things.

Your observation is correct.

Low ceilings are difficult.

When you design a work place lighting sysyem, you are trying to deliver the light to the work surface assumed to be 36" above the floor.

The spacing between fixtures is a function of the mounting height above the work surface and the "spread angle" of the fixture.

When it comes to lighting a workshop in a typical basement, it becomes a "what works" situation.

A single lamp fixture located on 32" centers worked for me in my basement shop a long time ago.

YMMV

Lew

Reply to
Lew Hodgett

The 8' ceiling is the controlling factor in the above application.

Use 1 watt per square foot for 100 FC maintained.

24 x 25 = 600

600/40 = 15, 40 watt lamps.

I'd probab;y use 16 lamps in 4 rows of 4 each.

That will provide about 6 ft spacing between rows which id probably about max.

BTW, those calculations were based on old lamps. Todays lamps provive same lumens for less watts.

It's the 16, 4 ft long lamps that is important.

HTH

Lew

Reply to
Lew Hodgett

I started to scan about ten pages from the illuminating engineering handbook, but realized no one does them by hand anymore. Its either rule of thumb, or we use software. Most distributers, have access to design software. I just ran it out real quick on one program 15

2/lamp 4' T8 fixtures for 80' candles, and 20 will get you a little over 100 FC. That assumes 70% ceiling, 60% wall and 20% floor reflectance. Also these are maintained FC, initial light levels will be higher. 2.5' work plane. 3 rows of 5 8' between columns and 5' between rows. Assume this is the center point of fixture. If I have time I'll run it on my best program and turn it out as a cad drawing and copy it to abp group. Newest program even does visual renderings of the interior space.

Mike M

Reply to
Mike M

What about the OSHA rules that are often quoted of 3 watts per sq foot for flourescents?

My proposed shop is 24x24 so I would need over 1,500 watts based on that. That seems like a lot. A space heater is usually 1,500 watts.

My thinking for my new shop is 4 rows of 8' T8 double bulb fixtures two per row. That is 944 watts which seems like a lot! Is that too much? I don't really want to burn a kilowatt an hour just for lighting.

My present basement shop only has about half as much light as I am planning for my new shop if I go full bore as described.

Brian Elfert

Reply to
Brian Elfert

Thanks, Lew, for the info.

Ricky

Reply to
Ricky Robbins

Here in Washington State if its a commercial Job is 2.3 watts per square foot for a carpenty shop which is about the highest allowed for any occupancy.

Mike M

Reply to
Mike M

I have no clue where that comes from but it doesn't apply to non commercial applications anyway.

Way too much.

I'd use 600 watts/40 watts/tube = 15 tubes +/-.

Not if you are going to be an engraver, otherwise yes, IMHO.

See calculation above.

Reply to
Lew Hodgett

That is known as the LGB theory of lighting design.

You bring in the out of town lighting guru from the factory.

Take guru to job site for an inspection.

Guru looks around and says, "Put luminaires here, here and here", pointing towards ceiling.

"Now, Lets Get a Beer."

Lew

Reply to
Lew Hodgett

If they do not take the lamp source into consideration, the above makes no sense at all.

Consider the following:

Incandescent: 18-20 lumens/watt on average. Fluorescent: 60-70 lumens/watt on average. Sodium vapor: 125 lumens/watt on average.

Those are initial values, but demonstrate the variation in efficiency of various lamp sources.

It is lumens on the work surface, not watts, that are important.

Lew

Reply to
Lew Hodgett

Basically they do consider that in that if you want more light you have to use the most effecient equipment. This is simplified as there are adders for high ceilings, and you treat rack lighting different. All though there is whats called the prescriptive method whereas you can have as many 2/L T8 fixtures as you want. For an office building it 1.2 watts per square foot.

Mike M

Reply to
Mike M

Reply to
Mike M

THANKS!

I needed a sanity check.

Barry

Reply to
Ba r r y

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