120° arc or 230° arc led tubes?

[matemike]

I'm going to light my 30x40 insulated metal building with 16 LED T8 fixtures. (4 rows of 4). The 2 outer rows will be at 12' height off the ground and the two inner rows will be at about 13.5' height. I cannot find much info on the web about the pros and cons of using a 120° vs 230° LED T8 bulb for my ceiling height. The obvious info is that the 230° bulbs will spread the light out more, but I'm trying to figure out if it will be better.


I've decided to go with this LED ready fixture already wired with no ballast.
http://www.beeslighting.com/product-p/st48232-led.htm

It's now between which of these four bulbs to use:
http://www.beeslighting.com/product-p/t8r-48-17l-50k-b.htm 1600lm 220° arc
http://www.beeslighting.com/product-p/t8r-48-18l-50k-b.htm 1800lm 230° arc
http://www.beeslighting.com/product-p/t8r-48-22l-50k-b.htm 2200lm 230° arc
http://www.beeslighting.com/product-p/t818w1200bixxdf50f1.htm 2212lm 120° arc

Normal fluorescent T8's put out 2850 lumens but in a 360° arc. Most of the light goes where needed, while some is reflected back from the fixture itself, but some is lost too.
The LED bulb that is last in the list will put out 2212 lumens in a 120° arc which is only 1/3 of the 360° arc but is 3/4 of the lumens. Will this be greatly noticable that even though it's putting out less total lumens, the concentrated arc will make it so much more direct that it appears 3X brighter when standing under it? If so, should I go with one of the other choices in the 230° arc range?

The Acuity lighting program says that 16 of the 2 lamp T8 fluorescent troffers will yield 753 lux in my particular shop with white ceiling and walls (I even painted the steel red-iron beams in my shop a semi-gloss white) It's bright in there. I'm trying to stay in the 750+ lux range btw.

Thanks for the help.

 

[cybrdyke]

Anything over 180 degrees is "uplight". Uplight will give you bounce off the ceiling and walls, which greatly aids in reducing shadows and creates a more evenly lit space, provided that your ceiling and walls are light in color. However, uplighting does not reflect 100% of the light, so some lumens are lost. FYI-You only get about 1700 lumens out of the fixture from a T8 lamp, even though the lamp is rated at 2850 lumens.

In my opinion:
The 120 beam is not optimal for a strip fixture in this case. It doesn't allow for anything other than downlight to the surfaces below. I feel like you'll get bright areas and dark areas unless you are very careful about placement and spacing.
The 18w 2200 lumen lamp would be optimal.

 

[matemike]

Thanks.

Forgot to add the fixture orientations:


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The rows will be about 5.5 feet apart across the 30ft width of the shop. And the fixtures in each row will be about 5 feet apart along the 40 ft length of the shop

 

[Nexussian]

I would try the narrower coverage, that high up it should disperse fairly well, and they don't appear to be very far apart on each side anyway.

That however is just my opinion, lighting is not what I do for a living.

 

[matemike]

I would try the narrower coverage, that high up it should disperse fairly well, and they don't appear to be very far apart on each side anyway.

That however is just my opinion, lighting is not what I do for a living.

The lines above are just to show orientation, the spacing is not to scale. The attachment is a better representation of the spacing.

 

[dslabuda]

FYI-You only get about 1700 lumens out of the fixture from a T8 lamp, even though the lamp is rated at 2850 lumens.

Is that because of the light directed toward the ceiling or some lumen-marketing bs like hp ratings?

Sent from my SAMSUNG-SM-N920A using Tapatalk

 

[matemike]

Is that because of the light directed toward the ceiling or some lumen-marketing bs like hp ratings?

Sent from my SAMSUNG-SM-N920A using Tapatalk

Probably both, but it's mostly attributed to the light that does not shine directly towards your work surface and was thus reflected back or completely lost.

I'm not designing my lighting layout based off lumens alone. I'm more concerned with the lux-feet that will be reaching my work surfaces. There are a trillion tables on the internet showing what amount lighting is needed in display cases, grocery stores, studios, fine detail working, office or desktop environments in terms of lux. The lists also show how each lighting situation is comparable to bright day, overcast day, sunrise/sunset, bright moon night, no moon night, etc. I'm trying to reach ~750 lux on my ~38" work surfaces while at the same time having an even distribution of light upon the walls and ceiling so there is no "cave effect" of having a shadowed corner or extremely dark areas above the lights.

I've been using this program:

https://www.visual-3d.com/tools/interior/

Unfortunately they do not have the DivaLites I linked earlier as one of their products.

Does anyone know what Lithonia light would be the best comparison to the LED T8 DiveLites I linked?

 

[cybrdyke]

Is that because of the light directed toward the ceiling or some lumen-marketing bs like hp ratings?

Sent from my SAMSUNG-SM-N920A using Tapatalk

2850 is T8 lamp lumens in a laboratory with a perfect environment.
Starting there, you'll have a "Normal" ballast that only fires the lamp to 88% full output. Then, you'll have a fixture of some type that will lose a percentage of the light. Common strips lights are only about 75% efficient.
2850 x .88 x .75 = 1881 lumens to the target.
A common T8 loses about 15% of its output over 24,000 hours.
1881 x .85= 1598.

In comparison, LED lumens that are reported on the box are real-world lumens.
And because of the tighter beam angles, there are virtually no fixture losses. LEDs will lose about 30% of their lumens over the life that is on the box.

I'm speaking in layman's terms, of course. If you want more technical terms, just ask.
Good luck
CD

 

[cybrdyke]

Probably both, but it's mostly attributed to the light that does not shine directly towards your work surface and was thus reflected back or completely lost.

I'm not designing my lighting layout based off lumens alone. I'm more concerned with the lux-feet that will be reaching my work surfaces. There are a trillion tables on the internet showing what amount lighting is needed in display cases, grocery stores, studios, fine detail working, office or desktop environments in terms of lux. The lists also show how each lighting situation is comparable to bright day, overcast day, sunrise/sunset, bright moon night, no moon night, etc. I'm trying to reach ~750 lux on my ~38" work surfaces while at the same time having an even distribution of light upon the walls and ceiling so there is no "cave effect" of having a shadowed corner or extremely dark areas above the lights.

I've been using this program:

https://www.visual-3d.com/tools/interior/

Unfortunately they do not have the DivaLites I linked earlier as one of their products.

Does anyone know what Lithonia light would be the best comparison to the LED T8 DiveLites I linked?

Lithonia doesnt offer lamps.
I dont think you can do what you're trying to do with that program.
CD

 

[MJockey]

I've been using this program:

https://www.visual-3d.com/tools/interior/

Unfortunately they do not have the DivaLites I linked earlier as one of their products.

Does anyone know what Lithonia light would be the best comparison to the LED T8 DiveLites I linked?

You can download the ies file linked in this post.

http://www.garagejournal.com/forum/showpost.php?p=5672840&postcount=259

I believe it was created to represent two james 18W, 5000k, 120 degree lamps in a similar fixture.

 

[crocket468]

I just tried to download that file per the instructions in that post, renaming the file once its downloaded doesn't change it from a .zip to a .ies file. Not sure how to make that work, Dialux evo wont import it.

 

[rburke65]

Wow...how lucky were we 20 years ago when we did t need to worry about this, huh?

 

[dslabuda]

Wow...how lucky were we 20 years ago when we did t need to worry about this, huh?

No doubt. I was just going to use the old calibrated eye/uneducated guesstimate method. I put a 4 bulb 8 ft t8 fixture over my main workbench with 4 (2900 lumen--or so they say) (4200k iirc) 4ft t8 bulbs and liked the light output. So I figured 14 of them in 2 rows of 7 in my little garage should be almost bright enough.

Sent from my SAMSUNG-SM-N920A using Tapatalk

 

[BVavra]

I'm going to light my 30x40 insulated metal building with 16 LED T8 fixtures. (4 rows of 4). The 2 outer rows will be at 12' height off the ground and the two inner rows will be at about 13.5' height. I cannot find much info on the web about the pros and cons of using a 120° vs 230° LED T8 bulb for my ceiling height. The obvious info is that the 230° bulbs will spread the light out more, but I'm trying to figure out if it will be better.


I've decided to go with this LED ready fixture already wired with no ballast.
http://www.beeslighting.com/product-p/st48232-led.htm

It's now between which of these four bulbs to use:
http://www.beeslighting.com/product-p/t8r-48-17l-50k-b.htm 1600lm 220° arc
http://www.beeslighting.com/product-p/t8r-48-18l-50k-b.htm 1800lm 230° arc
http://www.beeslighting.com/product-p/t8r-48-22l-50k-b.htm 2200lm 230° arc
http://www.beeslighting.com/product-p/t818w1200bixxdf50f1.htm 2212lm 120° arc

Normal fluorescent T8's put out 2850 lumens but in a 360° arc. Most of the light goes where needed, while some is reflected back from the fixture itself, but some is lost too.
The LED bulb that is last in the list will put out 2212 lumens in a 120° arc which is only 1/3 of the 360° arc but is 3/4 of the lumens. Will this be greatly noticable that even though it's putting out less total lumens, the concentrated arc will make it so much more direct that it appears 3X brighter when standing under it? If so, should I go with one of the other choices in the 230° arc range?

The Acuity lighting program says that 16 of the 2 lamp T8 fluorescent troffers will yield 753 lux in my particular shop with white ceiling and walls (I even painted the steel red-iron beams in my shop a semi-gloss white) It's bright in there. I'm trying to stay in the 750+ lux range btw.

Thanks for the help.

Have you decided on a light yet? I have a similar size building and I'm looking a good light and layout.