How much lighting do I need?

[PoorUB]

I have a 24 x 38 foot, or 900 sqft garage that I also use for wood working, metal working and engine work. Right now there is 24 4 ft, 2 bulb fixture wit the old T-12 bulbs. I came up with various info, but it seems right around 2,500 lumens per bulb, or about 120,000 lumens, so at 900 sqft around 133 lumens per sqft. I am sick and tired of replacing bulbs and ballasts and thinking of ripping them all out and going LED. I looked online at some varios lighting sites and it seems I may be close on lumens. I see anything from 125 to 150 lumens per square foot which seems reasonable to me as I would like more light than I have right now. 150 lumens per sqft x 900 sqft comes to 135,000 lumens.

Does this seem correct?

 

[Shiftless]

There is WAY more to it than lumens/ sq. ft.

Good idea to start all over with 4 foot long LED tubular or strip lights. The number and spacing you need depends on ceiling height, reflectance of the walls, etc.

Check out the layouts in the stickies at the top of this section.

 

[cvairwerks]

Color temp and interior wall color all come into play when working out your needs. Darker walls and selecting warmer color sources will tend to need more lumens to give the same appearances as cooler sources. Remember, as we age, we tend to need more lighting for the same tasks.

Personally, I tend to use lights in the 6000k or6500k range, white walls, high CRI’s and enough lumens to make an operating room seem a little bit dim.

 

[PoorUB]

The walls and ceiling are white. The floor has light gray epoxy. 9 foot ceilings.

I just want to cover the space with lighting as the work area varies by what I am working on. I don't see any way to locate the lights for work areas. Also there are a few obstructions in the ceiling that dictate where the lights get mounted. Where they are right now is about the best it can get. I have a pull down attic door, with lights on either side, and a overhead hoist that is tucked close to the ceiling so no lighting in that area, about an 8 foot chuck close to the middle of the shop.

Right now there are six fairly evenly spaced rows running across the 24 foot. I have them a bit tighter at the back end of the shop. Most of the work happens there, but like I said, it depends. I can get 4 - 4 footers across the shop in most of the current locations, so 24 fixtures. I can't do more, but I can do higher output. I like the 4 foot, prizmatic wrap around fixtures and it seems most of them are in the 4,000 lumen range except for some higher output fixtures that are about double that.

 

[MichaelInOr]

I replaced all my 4' fluorescent tubes with LED tubes from Walmart and I am quite happy with them. They are much brighter than the old fluorescent bulbs. I did NOT have to remove the balast before installing the LED tubes in fluorescent the fixtures.

 

[mogandave]

Buy two new tubes and try them. I replaced all my old tubes with LED and love them.

Used the same fixtures, just had to remove the starters.

If you use them a lot they pay for themselves pretty fast.

 

[cybrdyke]

PoorUB,
Lets get you thinking in the right direction and get rid of the misinformation that you've found. First, there is no such thing in lighting as lumens per square foot, so let's dump that notion. Also, the total amount of lumens in a space means nothing, so lets dump that, too.
Now, let's determine this...do you want to use the fixtures that are up there and just put LED tubes in them, or do you want to take them all down and completely start over? Either way is legitimate.
Next, your T12 tubes deliver about 1400 lumens each, depending on age, dirt, temperature, etc. In an 8' ceiling, we'd equate that to a 1650 lumen LED tube(x 2), or a 3000 lumen fixture. Of course, your new stuff will easily be over that. Common LED tubes are available in lumens up to 3000 each or more. Linear fixtures can be found up to 6000 lumens and more.
Finally, determine how much light you want....in foot-candles. For reference, a common warehouse is about 10fc, a school classroom is about 40fc, and a high end machine shop with detailed tasks is about 90fc.
Think about these things and get back to us.
CD

 

[PoorUB]

PoorUB,
Lets get you thinking in the right direction and get rid of the misinformation that you've found. First, there is no such thing in lighting as lumens per square foot, so let's dump that notion. Also, the total amount of lumens in a space means nothing, so lets dump that, too.

Funny, I have found several sites that use lumens per sqft. If it is incorrect, what methods do you used to figure out how much lighting to use?

As for the old bulbs I have found reference in several sites the claim around 2500 lumens per tube with T-12's. Foe example, https://www.bulbs.com/product/F40T12-CWSUPREME-ALTO

As for the fixtures, I want the old ones gone and put up new. I mentioned I like the 4 foot with a prismatic wraparound cover, similar to this, shop lights

 

[vavet]

I am by no means an expert on lighting, but I'll throw out my understandings (and possibly misunderstandings) to keep the conversation going.
Much like ***** and garage space, more is better. The answer to your questions is....all of it. You want all of the light.
Next, with the T12s - their light output is around the entire circumference of the tube. With the reflector, you got some of that light back down to the floor level, but it's more effective if the light output can be aimed where you want it initially instead of reflected. The LED tube ratings might be lower, but they point the light where you want it.

LED tubes comes in different flavors. Some require the ballast to remain in place, some require it to be removed, and some can work either way. The ones requiring the ballast to remain are problematic in that when the ballast goes, you're still replacing a ballast. I had two ballasts fail (out of 10 lights) shortly after my garage was built in 2017. The electrician initially installed the type that required the ballast to be in place, presumably because that was the easiest for him (cheapest for me). I ordered new tubes that required the ballast to be removed and handled that part by myself. The remaining 8 fixtures have been fine for the last 4 years so I haven't done any more changes, but I ordered a few extra LED tubes at that time.

 

[PoorUB]

I will not be using the old fixtures, so please no discussion on that! The old fixtures are a mix of some 1960 commercial, and 1970's prismatic wraps. They are all going away.

 

[Innovate1]

How much do you need? Opinions on that vary but I'd say just a little less than the Home Improvement episode - "Don't look directly at the snowman".

 

[cybrdyke]

Funny, I have found several sites that use lumens per sqft. If it is incorrect, what methods do you used to figure out how much lighting to use?

As for the old bulbs I have found reference in several sites the claim around 2500 lumens per tube with T-12's. Foe example, https://www.bulbs.com/product/F40T12-CWSUPREME-ALTO

As for the fixtures, I want the old ones gone and put up new. I mentioned I like the 4 foot with a prismatic wraparound cover, similar to this, shop lights.

Yeah, I know...the internet is filled with idiots and some of them even sound like they know what they're talking about. The whole "lumens per square foot" thing comes from a misinterpretation of the definition of how a foot-candle is measured. And once the misinterpretation was stated, it went all over the internet. It's not a thing. You'll just have to trust this 35 year lighting industry pro.
The method to figure out how much light you want is to determine how you intend to use the space and then find the recommended light level for that use. Recommended light levels are given by the Illuminating Engineering Society. I gave you some reference points in my previous post. Once you know how many foot-candles you'd require, you should get a lighting layout done. You can play around online with one of the many lighting calculators that are there, or you can ask the company that you intend to purchase your equipment from if they'll do one for you. Further, you can search through the "sticky" thread on this site that has dozens of similarly sized spaces already laid out. I think it's called "Lighting Layout Collection".

Your old T12's emitted around 2900 lumens when they were brand new. They've faded out over the years. The ballast performance has also declined. Your fixtures dont reflect 100% of those lumens to the floor, plus they're dirty. Your old T12's only deliver about 1400 lumens of light to the target. A replacement LED fixture will deliver nearly ALL of it's lumens to the target because it's new, clean, and doesn't use a reflector. The good news is that you can easily get one that's around 4000 lumens, like the one that you linked to, and it will be much brighter than your T12's.
A W-A-G is that 24 of those should do the trick, spaced 4 rows of 6, but if you're doing intricate work, or just think you want it brighter, then go with 30. Better still....get a layout done for you.
Hope that helps a little.
CD

....all of it. You want all of the light.

Fun to say, but spending time in overlit spaces can create tons of health issues. You most certainly want the correct amount.

 

[PoorUB]

A W-A-G is that 24 of those should do the trick, spaced 4 rows of 6, but if you're doing intricate work, or just think you want it brighter, then go with 30. Better still....get a layout done for you.
Hope that helps a little.
CD

Ok, pretty much what I was thinking. A lighting layout is pretty much a waste of effort because of the limited places to mount them. Where the current fixtures are now is pretty much the only place to put them, at least that makes any sense!

 

[78SC4X4]

5x5 in 24X40 5500 lumens each. I have them dimmed quite a bit. My free phone app say 120ish fc not dimmed

 

[rnixon]

Consider these ,from Pro Lighting , almost twice the output , at less than half the cost , of the lights you linked, and they're made in the USA.
I have 6 lighting 1/2 of my 1200sq.ft and 5 , 6 lamp high bays , rated at 15,000 lumens each , lighting the other half

https://www.prolighting.com/commerc...p-fixtures/48-inch/t443ssubcxx00p0-18w4k.html

https://www.prolighting.com/commercial-lighting/ledready/ledret8hiba/b4146ssumxx-18w4k.html

 

[PoorUB]

Consider these ,from Pro Lighting , almost twice the output , at less than half the cost , of the lights you linked, and they're made in the USA.
I have 6 lighting 1/2 of my 1200sq.ft and 5 , 6 lamp high bays , rated at 15,000 lumens each , lighting the other half

https://www.prolighting.com/commerc...p-fixtures/48-inch/t443ssubcxx00p0-18w4k.html

https://www.prolighting.com/commercial-lighting/ledready/ledret8hiba/b4146ssumxx-18w4k.html

You better check your math. The light fixtures I posted are $120 in packs of four, or $30 each

Also a higher output light with a nine foot ceiling isn't necessarily a good thing. I would rather have lower output fixtures and put in more of them to distribute the light better.

High bay lights are for exactly that, high ceilings. You certainly can use them on lower ceilings but you end up with a lot of light concentrated in a small area.

 

[dhally]

Fluorescent lights loose intensity as they age and get dirty. The old diffusers also get darker. This just to realize that they may be putting out less light than their original specs.

On the other hand, LEDs don't always spread their light as evenly, although the newer fixtures are getting better.

 

[rnixon]

Math skills are okay ,reading skills were deficient ,didn't catch the 4 pack.
I have the 3 bulb t-8 fixtures in the 9ft. ceiling space in my garage .The high bays are over a space with ceiling heights of 10 to 17ft. The layout and installed fixture heights were recommended by a lighting engineer
Good luck with your choices , lets us know how it works out.