overkill? lighting my shop

[NRChopshop]

ok heres the deal. I drew up a couple plans on paper and the one that made the most sense was this. Three rows of three 8' 4-bulb T8 lamps. I only run Cool White lamps. I don't like daylights. 9 lights seemed like the perfect fit right until i layed them out on the floor. Is 9 overkill or am i over thinking this? I laid out 6 and would probably be fine except with the door open. I ended up spreading them 1' more towards the end walls and 2' from the long side walls. It seems like it would help.

My building is 24x40 with only 8' ceilings and white walls. Will i get the reflection im looking for from the walls and floor?

 

[jjkrjh]

If you already have the lights I would put them in. You can put the lights on different switches and use them as you need them. Maybe even get by and only have 2 switches 4 on 1 switch(diamond pattern) and 5(x-pattern) on the other. I have the 3500k bulbs and really like them. It's always better to have to much light than not enough. If it's sunny outside my garage seems dark with the door open.

 

[NRChopshop]

Thats what i was thinking. two switches and leave it alone. The shop is dark to begin with. The one roll up door and 2 windows dont supply a whole lot of natural light since my property is shaded but 50ft pines.

 

[redsky49]

The total wattage (960W) works out to 1.8 W/sq.ft. which is in the neighborhood of acceptable lighting for an office environment. This is more than is typical for a garage with an 8 ft. ceiling, but not out of line for detailed work operations. I would suggest though that the light "throw" is not balanced and that the outboard fixtures should be moved outward toward the perimeter walls. These fluorescent fixtures have good throw to the sides, but little output from the ends. Photometrics are available for most all lighting manufacturers, and will be useful in determining the lighting pattern for the fixture you select.

Go single switching if you want to save some time and money. If the light output is excessive, remove one lamp from each fixture.

Yes, white walls and a reflective floor will increase the perceived light levels. The use of multiple fixtures will also help to reduce shadows that frequently occur when fewer fixtures are employed.

I have never encountered a situation where the light levels were judged too high.

As always, offered only as opinion

 

[redsky49]

Another consideration is that lighting levels will always decrease over time, due to natural aging, to the extent of 10-15%. This will be worse in industrial applications (garages and workshops) so that actual lighting levels may decrease 20-25% or more from new.

Instead of lamps being replaced due to a replacement schedule, as would be the case in commercial projects, most private users replace lamps only when they have burned out.

Install all nine fixtures.

As always, offered only as opinion

 

[rsanter]

for light distrubution I think you are on the right path.
for sure I would install the lights on either 2 or 3 switches depending on how you plan to use each of the spaces

bob

 

[rickairmedic]

I am a firm believer there is no such thing as to much light . There is such a thing as to little but I have never been in a garage that had to much light . I have 7 4' 2 tube fixtures and one 4 tube 4' fixture with 6500K bulbs in them and this is in a 21X25 garage and thre are times when its not enough light .

Rick

 

[om-nc]

FWIW, I have 13, 4 tube T-8, 8' fixtures in my 24'x32' shop. At 128 watts per fixture and 768 sq ft it works out to 2.16 watts/sqft.

I really like the light, I agree with Rick, you can never have too much light in the shop.

 

[smooth72]

More light the better, especially the older you get. I have a 30 x 40 with 11.5 ceiling. I have 10 8' t12 HO with 110 watts each so 20 110 watt bulbs on two switches. Every once in the wile I will change them all out and it is amazing how much they lose over time.

 

[A_Pmech]

I like to keep my shops around 1.8W to 2.2W flourescent per square foot. Nothing is more frustrating than trying to do precision work in a dungeon. Plus, it's just generally depressing.

I seem to recall a standard of about .75W per square foot for machine shops / mechanical garages in the code somewhere. That's way too low as far as I'm concerned.

Put 'em up! One suggestion: Space your fixtures closer to the wall, especially where you intend to install workbenches, unless you intent to install workbench lighting. Doing so will reduce shadows. The centers of shops generally don't require as much lighting as the edges, where most of the precision work happens.

BTW: I run only cool whites or "daylight equivalent" bulbs. Warm bulbs have a lower color temperature, which reduces visual acuity. It is preceptable when doing inspection and instrument work. It is also perceptible when doing something as simple as trying to work to a line on a belt grinder.

 

[redsky49]

The right perspective for lighting

Don't forget that most of the overhead lighting discussed on this forum is general or service lighting. It is not intended (or desired) to light all surfaces of your garage to heart surgery levels. Instead you should have a lighting level that does not encourage eye strain, and does not melt the paint on your car hood. It should allow you to find the dropped nut (assuming it didn't roll down the drain) and allow for general cleaning and normal day to day operations.

Task lights, whether drop lights or under shelf lights at the work bench, etc., should be used for fine or detailed operations. A fluorescent drop light, mounted centrally with a 20' cord, is invaluable for under hood or under car tasks, and certainly beats dealing with flashlights. If you are maintaining 40 candle power at 3" A.F.F. in general throughout the garage, you should
be in good shape. Close work may require 50 CP or more, but it might be required only for a 1 to 2 sq. ft. area.

You (the OP) are doing the correct thing by laying out the lighting plan on grid paper, but you must have the light pattern of the fixtures to avoid over lighting and subsequent dark spots. As you currently have the fixtures located you will have "hot" spots between the fixtures and dark areas toward the exterior walls. A successful lighting layout should be very consistent corner to corner of your space.

Work areas require more light, bulk storage areas less light. Plan accordingly. If creating a lot of dust, you may be better off with an enclosed fixture. If dealing with explosive vapors you should have listed fixtures for spark-proof applications. Maintain your fixtures by vacuuming the dust occasionally from the lamps. 8 ft. lamps can be a challenge to replace by yourself while standing on a ladder, and 4 footers are certainly easier to store.

Better quality ballasts are worth the extra cost. You will likely never have to replace one, they will operate more quietly, the lamp will start faster, etc. How you determine the quality of a ballast is extremely difficult to do. Other than looking for an instant start type and one with a high ballast factor (BF), you will have to ask elsewhere for expert advice.

Good luck with your project.

As always, offered only as opinion

 

[StealthM8]

My garage is similar in size - 26x36' with 11' ceilings.

Installed 16 eight foot 4-bulb T8 fixtures with 5000k GE bulbs. Most of the fixtures form a perimeter around the garage - spaced ~18" off the walls. There are a few fixtures tossed in the middle in strategic locations to light the sides and underhoods of vehicles/project areas.

Works out to 2.19 watts/square foot - Bright but definitly not overkill. Wish I had installed more lights...

 

[Stargeezer]

If you'll have workbenches along the walls-I'd hang twin 96" T8's over them just above head level. Otherwise-the ones you have laid out will cause shadows-as mentioned "Dark Areas" towards your walls. The 8 foot fixtures having 4 each 4 foot T8's yield more shadows over a twin tube fixture.

Here are two shots from my project which is still in-progress:

Above: You can see that the overhead lights cast a shadow at bench level on the bench that does not have the 8 footer lit. The other bench is well lit without shadows. The back edges of these fixtures are 12 inches from the wall.

In the tool room, where I will have sit-down benches and tables, the fixtures are spaced out from the wall a little more. There will be 3 Gladiator wall cabinets spaced apart on each of the 3 walls in this room.

Hopes this helps and illustrates the point of wall shadows from overheads placed inboard opf walls.

 

[nissan_crawler]

I would say you're about right. My garage is 19x23, with 8' ceilings and white walls (more or less half your size), and I have 9 4' dual bulb t8 fixtures (half of what you have), so we have about the exact same lighting in theory, and I say it's just right.

 

[ktm450]

think of it this way. You (at least I) want my garage to be lit like an operating room, not a bar. so, until I need to put on my rayban's, it's not to bright! My 24 x28 garage has 4ft two tube T8's, 12 of them, along with 6 R40 floods if needed. and undecabinet lights over each workbench. I've basically max'd out a 20A circuit just for lighting.

 

[om-nc]

Here are a couple of shots, without flash to give you an idea of the lighting.