Let their be light....

[vibenation]

Okay, for those that have already done this you won't be excited...

I have just recently acquired a new home, complete with two more garages than I previously had (they would be 0 btw) and gave one to the wife and claimed the detached as my own.

No, I did not pee on the floor to mark it but thought about it...

It is equipped with one measly little 2 foot long florescent "light" in order to have met code when it was built, but a firefly on a good day would put it to shame.

This weekend I shall be installing five 2 bulb T8 fixtures. Just going to demount the firefly shamed fixture, put one in its place, and then spread the other four out in a square pattern throughout the space like the look of the five portion of a regular dice.

The space is 24x27, with eight foot ceilings. Anyone care to weigh in on if I am going to need sunglasses for my Jeep and Motorcycle operating theater or if I am going to need to get more fixtures?

Keep in mind I want to keep the draw down, as for now there is but one solitary sorry 20 amp line plumbed into the garage and it has to run all the bits at once. Of course I plan to add some more juice, but that has to wait till I sell the townhouse we are abandoning in order to move into our new palace.

Plan is to string Romex out from where the original fixture is (that is how it is wired in currently) along the joists (like the few measely outlets throughout the space are wired) and to the new fixtures and tie the five fixtures into the switch. No plans for conduit or other reindeer games till the subpanel goes in later along with adequate outlets...

Five fixtures enough for a 22x24 space with eight foot ceilings? Will do before and after pictures for anyones pleasure if they feel so inclined to be washed by the pixels...

 

[MoonRise]

Let's see ...

Rough lighting rule-o-thumb is ~100 lumens/ft2 for 'precision' tasks. Brighter than a firefly but not as bright as an operating room.

24x27 space = 648 ft2 Let's call it 650 ft2.

100 lumens/ft2 x 650 ft2 = 65,000 lumens desired

Rough efficiency factor for fixtures is 80%, so for a desired 65,000 lumens 'output' we need 65,000 / 0.80 = 81,250 'raw' lumens

4 ft T8 tubes are ~2800 lumens output each (when new, light output falls of over time/use and although the tube may still 'light up' the output could just be 50% of the new value). So you need 81,250 lumens / 2800 lumens/tube = 29 (4 ft) T8 tubes.

Your proposed 5 fixtures with 2 4ft T8 tubes per fixture are not enough IMNSHO.

Yes, you don't always want or need all 100 lumens/ft2, so put the lighting on several different banks of switches.

8 ft ceilings are not all that tall for a 'shop', and also don't allow light to spread out from the fixtures all that much. Which means you have to put the fixtures relatively close to the walls or you end up with some shadows or dim zones along the walls.

Also suggest to paint the walls white (if they are not already that color, 'raw' drywall is not really white) to help spread/bounce the light around. Semi-gloss or satin/eggshell sheen to reduce/minimize harsh reflections and glare.

You still also need some directional task lighting.

29 tubes in 2 tube fixtures = 15 fixtures. Let's go 16 2-tube fixtures and rig them in four banks of four fixtures. 24 ft dimension/direction, and lets's put ~2 ft between the fixures in the row/line, so that gives four fixtures and each has a 6 ft 'run' (2 ft space + 4 ft tubes = 6 ft ). Yeah, that works, space/number wise.

YMMV.

[I have one space ~ 250 ft2 with ~8ft ceilings and I put 12 4ft T8 tubes ( three 4-tube fixtures) in that space (basement 'workshop'). The light level is OK and really not overly bright. I should redo it and put four 4-tube fixtures in there to even out the light better though.]

 

[vibenation]

Would love to run 15 fixtures but not gonna happen atm.

Have a total of 20 amps for the shop, with 15 fixtures I don't think I could run even the grinder without having to walk over to the other garage to reset the breaker.

I have a few 120w par 38 clip lights that I can place for specific area tasks.

Thank you for running the numbers and the other suggestions as well. It is unfinished, open ceiling and bare stud walls save for the roof stringers and for the life of me I can not figure out why. The roof peaks at nearly 20 feet, and I have NO idea why they did not put in scissor truss or the like to get at least 10-12 foot ceilings. The funny thing is that the attached garage has nearly 15 foot ceilings, and the attached garage was built to match it on the exterior. Obviously the people we bought it from used it to store the lawn tractor and little else. Maybe down the road we can raise the ceiling height, the only thing keeping it at 8ft is the size of my wallet atm which is quite dusty.

 

[MoonRise]

Hey, you asked 'how much light'.

Want it bright enough, you need more light. No free luch there.

At least you now have some numbers to see where you are 'now' versus down the road when the budget can add things. Like wiring and lights.



Maybe with the long-term view, rig up the existing space with a 'bright' corner/edge/wall and four fixtures there and then put the other fixture in the middle of the space as 'mood' lighting.

 

[Deckape]

I'm running four 2-bulb 4' florescents in a single stall of a 10 stall shop (the rest is mostly just storage). They hang about 7'6" above the floor. I have adequate light, but it could be better; I would suggest that you follow your own idea, (the '5' spot pattern) to begin with, then, you will get an idea if you need more or not.
Moonrise has given you good, solid, technically correct advice, right out of the code books. I agree with him about the lumens needed. But, you can't eat lumens. try 4 additional fixtures for a pay period, work in the garage a few nights, see how the light suits you. if it's too dim or inadequate for your purposes, buy a few more fixtures next payday. Simple enough?
I would also suggest you buy "low temprature" type fixtures, without heat, your lights will take an hour or more to reach full brightness. look at the 'Kelvin' or color temp rating of the bulbs too. the higher the better, blue = bright, yellow = dim. good luck!

 

[vibenation]

I swung back by Home Depot and picked up a sixth light today More the merrier I suppose eh...

Going to do two rows of three, with each row being cheated out towards the side walls for now. This will allow for an easy third row to go down the middle, minus where the garage door is when it is up when I have the sub panel added, and will sprinkle more in as needed.

For once in my life not constrained by budget, just available amps. i will do a pattern similar now to a six sided dice, with the two middle fixtures cheated in a bit to the middle to fill out the center of the garage a bit better.

Once the six are up, the clip lights will just have to fill in the holes for now, fortunately my work bench has its own 4' twin strip light for that type of work.

I got 6500K bulbs, I love that temperature. Ironically enough I have been a stagehand for 10 years or so, and am currently doing gigs with a lighting company in town. If I had the available amps, I would buy some old fixtures from my boss and get a suntan while working.

Will be sure to snap a before and after series of photos.

 

[eljefino]

RE your wiring in a "star" (spoke) pattern, usually stuff gets wired in a daisy-chain pattern. Will use about the same amount of wire either way, more or less, but you won't have one huge knot of splices in one center box, this way.

A compromise would be one romex going "east" and the other "west" with daisy-chains going from there on out. Whatever fits your operational needs.