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how much shop light?

F

fehdxl

Well Known Member
I've heard guys say that you can never have too much light in the shop. However, in anticipation of wiring my new 3-car airplane factory for overhead lights, I'm interested to learn how much light you all have and if you want more.

I suppose watts per square foot is the best comparison number, but raw details are good too. For example, 1.08 watt/sq ft is the same as saying 6 - 80-watt (2- 40 watt, 4 foot fluorescent bulbs) for my 21 x 21 shop.

Hope I'm not making this more confusing than it needs to be...

Thank you for your time!

-Jim
 
I suppose you COULD have too much, but... :)

My current workshop is about 20' x 20' and I have 6 of the 4' 2 tube fluorescent fixtures; it is pretty well lit but sometimes I would like more.
I'm moving to a place with a 3 car unfinished garage which I'm planning on wiring; it is a little deeper than standard and I'm considering three 8' dual fluorescent fixtures per garage spot. My brother just did his garage with a similar setup and it is bright.

Thomas
-8 wings
 
I've got 8 of the 2-tube fixtures in my unfinished 2-car garage and it's fine; however, having a finished garage with white walls makes a HUGE difference.

Steve Zicree
RV4 Wiring
 
Need light - go for 50 ft. candles

Jim ... 50 ft. candles (measured at a height of 2.5 ft.) is a good lighting level for shop work. Some delicate tasks (such as soldering small circuit boards) are better at 100 ft candles, but this can be done with additional task lighting.
An even lighting level with minimum shadows is best, and this usually means lots of separate fixtures.

Most folks have way too few lights.

You can't use watts per sq. ft. without taking the fixture type, light distribution pattern and construction into account.

So..... I dusted off an old lighting calculator CD and did your garage.

Assuming a light colored ceiling, 4ft., 2 lamp fluorescent fixtures mounted at 8 ft high, and average reflectance walls, and a typical concrete floor.

The answer was 12 fixtures in 3 columns (fixtures are vertical in a plan view)

This gave a peak of 56 ft. candles, an average of 52 ft. candles, and only a drop off to 35 ft. candles in the extreme corners.

If you want me to change my assumptions, let me know and I'll re-run it.

gil in Tucson ... did my hangar lighting this way. Came out so well I did three neighbours too...:)

PS Just did Thomas' garage using the same assumptions, but only 6 fixtures. With optimum fixture spacing, it came out at 29 ft. candles peak (right under the middle two fixtures) and dropped off to 19 ft. candles in the corners, and then dropped to 18 ft candles half way along the wall between the two columns of fixtures. The average was 23.5 ft. candles.

PPS Just re-calculated Jims with a non-reflective ceiling (peaked, unfinished garage with no wall board on the ceiling), and the same lamp layout dropped to and average of 43 ft. candles, a peak of 50, and 30 in the corners.
This shows a white painted ceiling is needed to keep all of the light levels up.


The fixture I used in all of the calculations was a Lithonia "C 2 40 GENERAL PURPOSE CHANNEL, 4' 2 LAMP T12RS", which I think is the 2 lamp, open surface mounted strip fixture sold at Home Depot.

C.200.jpg
 
Jim, WOW! You got ALOTTA replies already. I will keep mine short and sweet.

Yah, LOTSA light is a GOOD thing.

21 x 21 doesn't seem like a 3 car garage, but if you have little cars... well, anyways... Mine is 24 x 28 and I have FOUR - 8' Two lamp HIGH OUTPUT flourescent strips switched in pairs. It is REMARKABLY BRIGHT! I stll have task lighting in the paint booth and on bench areas.

If it gets below freezing and you want light, GET HIGH OUTPUT LIGHTS. Get them anyways, they don't cost much more anyways. $60 per strip.

Get 8' Two Lamp High Output Flourescent Fixtures!

Hope this helps!

:D CJ
 
I have a 500 sq ft basement shop with 8 ft ceilings. I have nine 4 ft four tube troffers (1440 watts) plus some under cabinet lighting. Sometimes I wish it were a little brighter, but it's pretty good. The ceilings are white and the walls are painted off white.

My heated hangar/garage is 1800 square ft. the walls are light wood or off white, the ceiling is white. I have 12 four tube troffers (1920 watts) in there. The ceilings slope from about 14 ft hight to about 9 ft. It's OK for general work, but not enough for close work. Some dark spots.

Hope this helps.

Roberta
 
Painting the floor

Jim,

I was amazed how much the lighting in my factory improved after I painted the floor a really light gray. YMMV

Dick
 
Roberta's light levels....

robertahegy said:
I have a 500 sq ft basement shop with 8 ft ceilings. I have nine 4 ft four tube troffers (1440 watts) plus some under cabinet lighting. Sometimes I wish it were a little brighter, but it's pretty good. The ceilings are white and the walls are painted off white.

My heated hangar/garage is 1800 square ft. the walls are light wood or off white, the ceiling is white. I have 12 four tube troffers (1920 watts) in there. The ceilings slope from about 14 ft height to about 9 ft. It's OK for general work, but not enough for close work. Some dark spots.

Hope this helps.

Roberta
Click to expand...

Dust off the old CD again....

If Roberta got the light fixtures correct, she should be glowing in her basement...:) ... and making the rest off us look dim.

I calculated 100 ft. candles average, max. of 115 and a min. of 76.

Roberta - do you really have 4 tube fixtures, or are they 2 tube fixtures, which would give half of the numbers above?

Roberta's Hangar/garage comes out at 38 ft candles average, max of 46 and a min. of 26. The fixtures are probably spaced a little further apart than the manufacturer would recommend (hard to say without an exact part number) in that the light drops off in between the fixtures that are 14 ft. apart.
For an even light level, you usually want more fixtures closer together. This fits in with Roberta's "some dark spots" quote.

Gil in Tucson .. calculating away.

I can do anyone else's workshop...
I need width, length, height - can only do simple shapes
Surface type/description of the ceiling and walls
Type of fixtures.
If I set the required light level to 50 ft. candles, it will calculate how many fixtures you need and the optimum spacing.
If you are serious and really building, I can do a more precise calculation, with exact manufacturer's parts, if I can get the appropriate IES file that describes the 'shape' of the light output. These are usually available on the web.
 
The lite fixtures have 4 tubes each 48" long. Here are some shots of the shop and hangar. They are a little lighter than these photos show. But they are in no way too much light. The lense panels do cut down on the light, but also reduce glare and diffuse the light better. Troffer lights are more of a finished looking light as opposed to the open tube shop type lights. The shop is just about perfect, with a few work station lights positioned over counters and power tools. The hangar could have used a few more lights during building, but for now are OK.

Roberta

P.S.: Looks like I may have some tubes out on some shop lights, but they are all 4 tube fixtures.


shoplites7bc.jpg



hangarlites7vo.jpg
 
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Roberta and a well lit basement

Roberta shows the need for lots of light....:)

I recalculated her basement for less reflectivity off the floor and walls, but a lower ceiling than I had originally (looks like a 7 ft dropped ceiling in the pic.)

Comes out to 94 ft. candles average.

This is a good number for close work, and Roberta says she sometimes wishes for more light....

The 50 ft. candles I quoted is a recommended level for general work, and should really be considered a minimum for RV building, since most construction takes place in the middle of the floor, and not at well lit workbenches.

AS A REFERENCE

The standard new house finished garage (22 by22 ft) in our area usually comes with two 4 ft. 2 bulb strip florescent fixtures.
This gives an average of 14 ft. candles and a peak of 25 ft. candles directly under the fixtures.

To get an average of 50 ft. candles, you need 9 of these fixtures evenly spaced on the ceiling -- Actually calculates out to 52 average, 59 max., and 42 minimum - pretty even lighting.

FLOORS

I took the same garage as above, and increased the floor reflectivity from 20% (the default) to 40% (a guess at a light colored paint). This upped the average to 58 ft. candles, which would be noticeable.

...gil in Tucson
 
The ceilings are 7'-8" . we have a 13 course basement. The door to the family room looks high because there is a step down. I have 7 of the lights in the major portion of the shop and two more located in an "L" off the main floor. The floor space is 15' X 25' with the "L" being about 12' X 15'.

Roberta

Just a note. Estimates on lighting I have encountered have always been defficient and required additional lighting. Not all lighting programs consider all conditions and uses.
 
Calculations

robertahegy said:
The ceilings are 7'-8" . we have a 13 course basement. The door to the family room looks high because there is a step down. I have 7 of the lights in the major portion of the shop and two more located in an "L" off the main floor. The floor space is 15' X 25' with the "L" being about 12' X 15'.

Roberta

Just a note. Estimates on lighting I have encountered have always been defficient and required additional lighting. Not all lighting programs consider all conditions and uses.
Click to expand...

Yes... most designers don't take into account the degradation with age... and they only use the data sheet height/spacing numbers.
It also depends on what light level they aim for for various tasks, and whether they go for energy savings...
This program uses the measured light distribution from each fixture and does a sum for each calculation point. It's simple physics. The variance mainly comes from the reflectivity numbers... white walls are good, but get less reflective when covered by cabinets and tools...
The other major factor is degradation with age. A factor of 0.64 was used (recommended by the program) to allow for the loss of light with age of the bulbs, and for dirt/yellowing of the plastic covers on the fixtures.

RECALCULATE

Roberta... I did your main 15 x 25 area with 7 fixtures and 7.66 ft height, and calculated 71 ft. candles avg., 90 max. and 30 min.

With a few bulbs missing, and using Home depot bulbs such as "Philips ALTO? 40 Watt Cool White Delux T12" which start out at 2200 lumens instead of the 3200 lumen high output bulbs I assumed.... I got 50 ft. candles avg., 60 max. and 21 min.

So perhaps you are closer to the recommended value after all.

BULBS

When you buy florescent bulbs, check the lumens output rating on the package - try and get 3000+ inital lumens for a 4 ft. bulb.
Some states (CA where I used to live) only allow lower wattage, and output, for residential uses. Try a commercial outlet.
Most manufacturer's bulb specifications are somewhere on-line if it's not on the packaging.


gil in Tucson

Who used to make light measuring instruments for a living a long time ago
(United Detector Technologies - chief engineer, instruments)
 
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Here is what I put in

Just went through the same decision process for our shop. I ended up putting in six of the 8 foot high output flourescents in our 30x36 shop with 10 foot ceilings. I also have some 4 foot fixtures that will be added above a couple of wall work benches below some shelving. Our ceiling is light and the walls will be white at some point in the future. I had planned on paiting the floor a light grey but am not sure I need to from a lighting aspect. We have plenty of light with few shadows.
 
12x28 shop, all white... (10) 42w (same as 200w incandecent) spiral fluorecents....very bright...even brighter than it looks in the picture

dcp06413zl.jpg
 
Gees, Gill. I'm glad you clarified that degrading with age thing. I thought you meant me for a while.LOL.

You are absolutely right about cheap tubes. Those are the sale ones and they are degrading. But when you need to buy 80 or so at a crack, you tend to go for the cheapies. They do OK. They're not on so much anymore since the plane's finished.

Good info you're furnishing. Thanks. ;)

Roberta
 
JohnR shop calculations

JohnR's shop calculates to 35 ft. candles average, 35 max. and 24 minimum.

If I assume 8 ft. long, two lamp, high output strip lights...

The poor part is an uneven spread. At a 10 ft. mounting height, the manufacturer recommends a spacing of 11.7 ft between rows, and a 1 ft. spacing end-to-end of the fixtures.

These spacing numbers are needed to keep a fairly even light distribution around the work surface, which I set to 30 inches high (table top height).

I did assume an even spread of the 6 fixtures across the ceiling. If the rows are biased towards the center, more light would be central, and the drop off at the sides would be compensated for by the extra 4 ft. fixtures - presumably over work benches.

A screenshot of the output is here...

JohnR.JPG


...gil in Tucson
 
ship's shop

My calculations for ship's shop are not as precise, since the bulbs he used are not usually exposed, however, a rough estimate gives even lighting at 55 ft. candles average, 61 max, and 41 min. Since it's a long, narrow shop, the drop off is only at the extreme corners, the sides of the shop are well lit at 51-52 ft. candles.

The higher ceiling also improves the evenness of the lighting, which is only varies from 59 to 61 ft. candles across the center of the room.

This is as bright as recommended, which may look very bright, as ship says, compared to most shops.

The point sources may add a little glare though, compared to strip lighting...

...gil A
 
This is definitely not intended as a flame, but more of some advice for the newbies. Don't get too stressed out about having exactly the right lighting, compressor, pneumatic squeezer, bandsaw, etc. I built all the way through the slow build wings in a really crappy garage with really crappy lighting and only the tools that were really needed, and the thing is coming out just great. As long as your eyeballs are healthy you'll be able to see everything with the lights off and the garage door open.

On the other hand, when it comes time to make wiring harnesses and such, you'll need one of those miner helmets and x-ray specs to be able to see all the little tiny connectors. Ask me how I know.

Steve Zicree
RV4
 
Lights

No flame taken, but this is a little different from tool selection.
It's not a difference between Sears and Snap-On, foot-candles are the same wherever you buy them...:)

The inital question was "how much light?"
You can work with less, but will it give you eye strain or lessen your working tolerances because you can't see where that drill bit is exactly going?

Many folks set up their garage specifically for building, and this time, it's onlly $19.99 at Home Depot for a 2 lamp, 48 inch strip fixture.
So why not just put enough lights in at the beginning?

SAMPLE GARAGE CALCULATION

For a 24 by 24 garage with light colored walls and a solid ceiling at 8 ft. high, 12 of the above $19.99 fixtures (Model C 2 40 120 MBE) give an average of 51 ft. candles, with the fixture centers spaced 6 ft. apart.

If you only install 9 fixtures, you drop to 39 ft. candles with a "hot spot" in the center.

The 50 ft. candles will reduce eye strain over the long run...

....but pick your light level... it's only your eyes...

gil in Tucson
 
Gil, you have it pretty close except the 8 footers are centered in the building. Also I failed ot mention that there are 2 foot deep cabinets floor to ceiling on two walls that are painted white. The bench areas will be lighted with the 4 footer which I used to have for the main lighting. My wife thinks she needs sunglasses when she comes out ot the shop now. :cool: I think it will be plenty of light for me but the 4 footers sure didn't cut it. Also the 4 footers didn't like the cold very well. :eek: If the shop was kept at 50 or so they started real slow. Thanks for your analysis, I find it rather interesting.
 
JohnR shop

"Gil, you have it pretty close except the 8 footers are centered in the building"

John .. can you describe the layout a little better? I'll re-do the calculations...

thanks gil in Tuson

PS the sunglasses comment makes sense compared to most garages...:)
 
How much shop light?

Here is what I did. I have a three car garage with 9" ceilings. I basicaly used the 8' cold weather florecent kind from HD or Menard. Then, when my neighbor says "WOW I can't believe how much light is coming out of your garage" I stopped installing lights.:) nuff said..

Richard
RV7A
Wisconsin
 
Cheaper Alternative to Fluorescent Fixtures

larger-image.asp

Clamp Light

I have a 24 X 24 unfinished garage. With about a dozen different lamps, 4 separate circuits. Turn them all an and it is bright. In addition to background lighting two or three of these things aimed where you are working brightens thinks up considerably. During the winter I run standard 100w incandescent bulbs, during the summer compact florescent bulbs keep things cooler. With the unfinished garage I can clamp these things anywhere.

Cheers
Warren
AHYUP.COM
 
Offer to Calculate Shop/Hangar light levels

OK, with the last post, the ratio of useful information has reached a level of diminishing returns.

I will still offer to calculate anyone's light requirements as best as I can, but by private e-mail only...

E-mail me at gilalex (at) earthlink (dot) net

I'll add no more to this thread...

gil A :confused:
 
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thanks!

All I got to say is--wow! Thanks to everyone for all the info! You guys and gals rock! -Jim
 
Lighting

Before I remodeled the garage they had one 60 watt bulb in the entire 24 x 24 garage. The ceiling is sloped with the roof and the walls are painted white. I have a 500 watt haligon lights about four foot in from each corner (4) and two more switchable 500 watt haligons evenly split between the other four. So far it has worked well for us.
 
I finally have some real world experience to report on my new shop light setup. All of the new light fixtures were fired up for the first time this weekend. All I can say is SWEET! I sent some info to Gil and he commented on my plan with some hard model data. Thanks Gil. I made some modifications based on that. Really, the key is just geometric consistency. It really does make a difference.
My fixtures are Lithonia C 2 32 120 GEB10IS with Philips Alto T8 4100K 32W 2950 lumen 48" bulbs. The 4100K color is the right color for me. The ceiling is painted white and there are no shrouds or reflectors on the fixtures. They are mounted to the ceiling at 9' high. The light throughout is going to be plenty bright and is very consistent throughout the entire space. I have the fixtures on a total of four circuits/switches so that they don't all have to be on at the same time. Like if Tanya wanted to just go out to get a screwdriver. Yeah, she is allowed.
I'll post some pictures here as soon as I get them off of the camera and the space is a little more presentable. My as-built layout is as follows:
lightfixture_layout_Page_2.jpg

IMG_1269.jpg

Oh, yeah, and I just realized that I can enjoy the distant sunset out the rear window that I just had installed in the back wall of the garage :).
 
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Still open....

az_gila said:
.......

I will still offer to calculate anyone's light requirements as best as I can, but by private e-mail only...

E-mail me at gilalex (at) earthlink (dot) net

I'll add no more to this thread...

gil A :confused:
Click to expand...

The offer is still open.... gil A
 
Control it.

Utilizing switches try controlling the areas you wish to light. It is great to flip a switch and have super bright conditions ( a subjective description ). There are other times such as laying on your back looking up into a bright light where the light can be a disadvantage. Eye fatigue can be caused by constantly moving your eye from a light ( closing retina ) area to a dark ( opening retina ) area. You will find by simply being able to turn off some of the lights in your field of view and using portable task lighting helpful. In the case of a shop separately switching the center, main task, and the perimeter lights ( over workbenches , shop tools, and storage helpful.
 
Gil,
Is it possible to convert foot candles data into a practical rough rule of thumb, perhaps "square feet per tube" or "square feet per foot of tube"?

Data point; 1120 sq ft, white ceiling, 24 eight foot tubes (12 double fixtures). Works out about 50 sq feet per 8-foot tube.

 
Numbers...

DanH said:
Gil,
Is it possible to convert foot candles data into a practical rough rule of thumb, perhaps "square feet per tube" or "square feet per foot of tube"?

Data point; 1120 sq ft, white ceiling, 24 eight foot tubes (12 double fixtures). Works out about 50 sq feet per 8-foot tube.

......
Click to expand...

Dan... the simplest conversion would probably be watts/sq. ft.

For the average 50 ft. candles illumination at 30 inches high a number of 2watts per sq. ft. is at the low end of what you need.

This assumes an 8 ft. high workshop, reasonably light colored walls and high efficiency fluorescent fixtures (use 80 watts per 8 ft. bulb, and 40 watts per 4 ft. bulb), add more watts for cheap bulbs...:rolleyes:

If your shop is sort of square (33 x 34 ft) and has 8 ft. high ceilings, with 12 fixtures you are in the "nice and bright" category....:)

Your shop calculates at 95 ft. candles peak and only drops off the 65 ft. candles in the corner... lots of light for precision work.

One of the troubles in our size shops is the 8 ft ceiling height. For an even illumination, there is a recommended spacing of the fixtures, and this works out to about 8.5 ft. But with our low heights, and no diffusion on the typical fixtures used, this works out to about 120 ft candles - which is bright. Spacing the fixtures further away from each other makes the light less even - and may be more "harsh" of a subjective basis.

That is why lights in troffers (see Roberta's earlier post) makes the light more uniform and subjectively pleasant....:)

One option is to use the cheaper 4 ft 2-bulb fixtures like Scott did. In this case spacing the fixture rows 6 ft. apart, and having an end-to-end spacing of 2.5 ft would give a nice even illumination at the 70 ft. candle level. More spacing in either direction lowers the uniformity. These numbers are in the same ballpark as Scott's eventual design.

As a side-note: this spacing would also work well for the cheaper bulbs, lowering the illumination somewhat, but still above 50 ft. candles, while remaining uniform.

gil A
 
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I got totally cranked up about the light levels in my shop back when I was working on the practice kit. I didn't (at the time) have any knowledge of "ideal" or "acceptable" light levels, I just knew I wanted a bunch, I was tired of trying to work in a cave by firelight. I ran down to Lowes and bought a pile of fixtures, installed them, and life was good. My wife came out into the garage, raised an eyebrow, said "Let there be light!", threw another disapproving glance my way, and departed.

I calculated my light levels based on these conversations, I'm at 2.7 watts per square foot, with one fixture hanging directly over my main work bench for a slightly higher level in that spot. Lovin' it!
 
Vote for the spiral jobbies

My garage is about 950 ft^2, with 10' ceilings. I have about 12 screw-in sockets, each with a 100 watt equivalent spiral florescent. I have never particularly liked the light that comes from tube florescents, but I really like the light that comes from the spirals. Seems to be whiter/brighter. Plus, easier to add additional fixtures. Total juice consumed is only about 300 or so watts for 12. When it is cold, they might take 2 minutes to get to full brightness.

Of course, since Washington has mandated them, I might have to rethink...
 
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Good Choice

scard said:
I finally have some real world experience to report on my new shop light setup. All of the new light fixtures were fired up for the first time this weekend. All I can say is SWEET! I sent some info to Gil and he commented on my plan with some hard model data. Thanks Gil. I made some modifications based on that. Really, the key is just geometric consistency. It really does make a difference.
My fixtures are Lithonia C 2 32 120 GEB10IS with Philips Alto T8 4100K 32W 2950 lumen 48" bulbs. The 4100K color is the right color for me. The ceiling is painted white and there are no shrouds or reflectors on the fixtures. They are mounted to the ceiling at 9' high. The light throughout is going to be plenty bright and is very consistent throughout the entire space. I have the fixtures on a total of four circuits/switches so that they don't all have to be on at the same time. Like if Tanya wanted to just go out to get a screwdriver. Yeah, she is allowed.
I'll post some pictures here as soon as I get them off of the camera and the space is a little more presentable. My as-built layout is as follows:
lightfixture_layout_Page_2.jpg

IMG_1269.jpg

Oh, yeah, and I just realized that I can enjoy the distant sunset out the rear window that I just had installed in the back wall of the garage :).
Click to expand...

I am the Lithonia Lighting representative in Oregon and SW Washington. While I chose to use their sealed DMW fixture in my own hangar (32 of them!), the simple C strip is a good choice when you mount them directly on a white ceiling to act as a reflector. The big difference in the fixtures you chose and those you pick up at the DIY centers are the efficacy. Watts per square foot that some people are using does not take into account efficiency at all, so be careful of that, especially if you are buying cheap fixtures that may be very inefficient.
By the way, you can go to Lithonialighting.com and find a downloadable free piece of software that will calculate the expected footcandles based on fixture type, spacing, etc... Very easy to use, or anyone interested can PM me and I will do a layout for you.
I have done many hangars with the C strips as you have done. I choose Sylvania 835 series lamps (3500K vs 4100K) but that is subjective. The Philips lamp is a good lamp with good color rendering, important when you start dealing with colors like wire insulation and such.
Good job.
 
Light fixtures

JonJay said:
I am the Lithonia Lighting representative in Oregon and SW Washington. While I chose to use their sealed DMW fixture in my own hangar (32 of them!), the simple C strip is a good choice when you mount them directly on a white ceiling to act as a reflector. The big difference in the fixtures you chose and those you pick up at the DIY centers are the efficacy. Watts per square foot that some people are using does not take into account efficiency at all, so be careful of that, especially if you are buying cheap fixtures that may be very inefficient.
By the way, you can go to Lithonialighting.com and find a downloadable free piece of software that will calculate the expected footcandles based on fixture type, spacing, etc... Very easy to use, or anyone interested can PM me and I will do a layout for you.
I have done many hangars with the C strips as you have done. I choose Sylvania 835 series lamps (3500K vs 4100K) but that is subjective. The Philips lamp is a good lamp with good color rendering, important when you start dealing with colors like wire insulation and such.
Good job.
Click to expand...

Jon... which particular model of the C-Strip do you recommend for hangars that meet the NEC code for "hot frangible bits falling on airplanes in case of bulb failure" (or similar wording....:)....)?

And how do the fluorescent compare to Lo Bay HID lights for efficiency in a large area such as a hangar?

gil A

PS I did just discover the Lithonia sw, and it is neat and easier to use than the Visual one I have.... but it won't allow for your competitor's light fixtures...:D
 
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