More shop lighting....ceilings and lumens

[Jeff Bartley]

Sorry to add yet another lighting thread to the mix.

So when you consider ceiling height and lumens is a higher lumen fixture more effective than a lower lumen fixture as ceiling height increases?

Stay with me for this example: let's say you're comparing one 8000 lumen fixture vs two 4000 lumen fixtures. The lumen output is equal but does the 8000 lumen fixture get more light to the bench?

I have two lighting plans in front of me and one specifies less fixtures (9 total) with a greater lumen output per fixture and the fixtures are hard wired. The other uses more fixtures (20 total) that have a lower lumen output per fixture and these are the less expensive plug in type fixtures.

Overall lumen output is 58000 (for 9) vs 82000 (for 20). And the 20 fixtures are roughly $200 less but require 12 outlets in the ceiling.

Still waiting to hear back from another light supplier who has 92-95 CRI LEDs which for fixture type and lumen output compare closest with the 9 in the above scenario.

Ceilings are mostly 12', building is 36'x30'.

Anyone have a thought on this? Help!!

[Jim Becker]

High-bay fixtures tend to have higher output for obvious reasons...they need to project the light farther for proper coverage. Coverage angles may vary with different fixtures, too, and that needs to be accounted for to get even coverage without having harsh light in some places and inadequate light in others. That said, a 12' ceiling isn't "high" in the general sense, albeit it's 4 feet higher than a typical 12' ceiling. I don't honestly think you're going to have a huge issue with selecting fixtures for your situation...things would be different if you had a very large shop building with very high ceilings...you know, in the 18-24' range. If you are building new, instead of "plug in" fixtures, why not direct wire fixtures? That eliminates the cost of the outlets altogether.

[Thomas Crawford]

Have you tried this tool:
http://www.visual-3d.com/tools/interior/default.aspx

LED tubes are available under Lithonia->strip light

For my shop I think I'm ending up with 12 4' dual-tubed 2300 lumen fixtures. I'm 20x28 with 10->12' vaulted ceiling, so I'm "mostly 12' as well". I put the target at about 500 lux at workbench height.

[Mike Heidrick]

12' is not even low bay. Pretty sure low bay starts at 14'.

A 6bulb t5ho fixture is 30000 lumen. The prob is 12' wont give you the distance needed to disperse the light wide enough for good coverage with that fixture.

Folks seem to like cheap led setups at 12'. Wonder how many have ever seen good lighting. They lead with their pocket book and not science. They only have to make themselves happy.

[Thomas Crawford]

12' is not even low bay. Pretty sure low bay starts at 14'.

A 6bulb t5ho fixture is 30000 lumen. The prob is 12' wont give you the distance needed to disperse the light wide enough for good coverage with that fixture.

Folks seem to like cheap led setups at 12'. Wonder how many have ever seen good lighting. They lead with their pocket book and not science. They only have to make themselves happy.

What do mean by cheap? Low CRI?

[Mike Heidrick]

Cheap like $20 vs $300+ for low bay led.

[Jeff Bartley]

12' is not even low bay. Pretty sure low bay starts at 14'.

A 6bulb t5ho fixture is 30000 lumen. The prob is 12' wont give you the distance needed to disperse the light wide enough for good coverage with that fixture.

Folks seem to like cheap led setups at 12'. Wonder how many have ever seen good lighting. They lead with their pocket book and not science. They only have to make themselves happy.

I'm asking the 'science' question so that I get it right the first time! Low bays are definitely not what i'm considering for the exact reason you mention. I'm trying to compare two scenarios of fixtures to determine the optimal plan. Price is about the same so my pocket book has nothing to do with the decision but even if it did I am unfortunately bound by a budget! Sure would be nice to leave the budget out of choices like this.

[Jeff Bartley]

Cheap like $20 vs $300+ for low bay led.

The price between the two is $36 for the plug-in type and $104 for the higher lumen direct wire.

[Jeff Bartley]

Thomas, that's pretty neat. I messed around with it a bit, I'll have another look at that later this evening.

Jim, I'd definitely prefer to have hard wired lights. That being said the plug-in type does offer flexibility which might be useful if machines were moved around in the future. On the other hand, the more expensive hard wired lights are actually serviceable which is a plus. And even if I wanted to add another light they allow you to run conduit from one light to another to daisy chain them together. Not as easy as a plug but doable.

[John K Jordan]

Lumen numbers can be misleading, accidentally or on purpose. The total light emitted from a bulb is measured in lumens but it counts the light that goes in all directions whether or not it ever reaches the work area. It is measured by putting the light source inside a calibrated integrating sphere. Since these are very expensive, especially as they get larger, typically the LED or bulb is measured instead of the fixture, if even that. (When I worked in an optics lab we had a fairly small integrating sphere and it had cost thousands of dollars.) Unfortunately, some light fixture makers apparently just estimate or make up lumen numbers. They love to state large lumen numbers for the emitters even if the emitter is installed in a fixture that absorbs a significant amount of the light. The higher the fixture the lower the light intensity at the work and the more the spread.

I think a light meter is more useful for comparing two fixtures since it measures the light at a particular place and distance from the fixture. However, it might not be possible to measure the fixtures before you buy. As for the amount of light that actually reaches center of the bench you have to consider the spread and position of the fixtures. I use this cheap light meter which seems to be OK: https://www.amazon.com/gp/product/B0075ZS8VQ

This may be a useful picture:
http://urbanvelo.org/candela-lumen-l...-do-they-mean/

I use 4-bulb T5 fluorescent high bay fixtures in my shop with mirrored reflectors above the bulbs to direct more of the total light downwards. Some visitors have commented they needed sunglasses. I like the light. Before I bought and mounted the fixtures permanently I bought and mounted one temporarily to judge the intensity and spread.

JKJ

[Bill Dufour]

Lumens is lumens. You need so many lumens per square foot to be bright enough for the work you do in that spot. Same idea as lawn sprinklers. Your example one set up is about 3/4 as bright as the other.
But just like sprinklers in gallons per minute you need to figure out if it is evenly spread out or are some areas nothing hits it ,and right next to the head it gets a lot.
The light spreads out with distance, and fixture design, Do you want pools of bright light and dim areas between or overall equal brightness.
Bill