Another 2 Car Garage Lighting Situation...

[Mr. Brooks]

First, I tried searching up down left right for similar scenarios, some helped, some didn't. I would rather ask than regret later.

Existing lighting.
1 switch controlling 1 CFL in middle of rear of garage behind garage door opener...useless and no bueno

Plan thus far
8x 4 bulb 8' T8 fixtures
2 rows of 4 length wise

Switching question.
How can I wire the back 4 to the existing switch (guessing remove cfl fixture, turn into junction box). And how can I then wire the front 4 that will be covered by the garage door when lifted to a different switch without running a separate run from the panel (if possible). I currently have 100ft 12/2 with ground Romex if that helps.

Summary.
1 switch for 4 8' lights
1 switch for 4 8' lights blocked by garage door to not waste energy.

 

[pattenp]

You first need to figure out if the one light is on the circuit that the garage door opener is on. And regardless of that, you need to know what total loads are on that circuit and what the circuit size is before you add eight T8 light fixtures.

 

[Mr. Brooks]

From what I know and can tell the garage is split between two 15 amp circuits.

1 GFCI with one outlet in the back wall and one in the ceiling (connected to it are my cord reel and the garage opener). Also connected to same circuit is the sprinkler system and alarm system.

Other 15 amp circuit is what feeds to the switch in question, 1 cfl in garage, 1 outside driveway light, cfl in laundry room, lighted chandelier in breakfast nook, and 4 can lights in kitchen.

After stepping back and looking at what's connected, seems a new run for lighting is necessary unless you guys disagree.

 

[sands35]

Each 8' T8 will pull about 60 Watts (ballast load included) (though I've seen up to 75 Watts listed on some - you'll need to check the specs on what you want)

8x4 = 32 bulbs
32 bulbs x 60 = 1,920 Watts
1,920 Watts / 120 VAC = 16 Amps

You will need 2 15 amp breakers or 1 20 amp breaker for the bulbs you plan. (So I wouldn't use the existing circuits)

IMHO, the simplest way to do this is to wire in surface mount conduit with switch and outlet boxes on the ceiling. Then use surface or hanging corded fixtures. You can move them around and add more later if you need more light. You can pull NM through conduit, just pay attention to conduit fill.

Garage is finished? Do you have access to above the ceiling? Crawl space / attic, etc.?

You didn't say what you are going to do in your garage? Basic car maintenance, Wood shop, fabrication? The more detailed the work, the more light needed.

8, 4 bulb, 8' fixtures is a lot of light.

 

[Mr. Brooks]

Each 8' T8 will pull about 60 Watts (ballast load included) (though I've seen up to 75 Watts listed on some - you'll need to check the specs on what you want)

8x4 = 32 bulbs
32 bulbs x 60 = 1,920 Watts
1,920 Watts / 120 VAC = 16 Amps

You will need 2 15 amp breakers or 1 20 amp breaker for the bulbs you plan. (So I wouldn't use the existing circuits)

IMHO, the simplest way to do this is to wire in surface mount conduit with switch and outlet boxes on the ceiling. Then use surface or hanging corded fixtures. You can move them around and add more later if you need more light. You can pull NM through conduit, just pay attention to conduit fill.

Garage is finished? Do you have access to above the ceiling? Crawl space / attic, etc.?

You didn't say what you are going to do in your garage? Basic car maintenance, Wood shop, fabrication? The more detailed the work, the more light needed.

8, 4 bulb, 8' fixtures is a lot of light.

Yea I agree, lot of light, but the whole GJ thought of more light is better has stuck in my head. I was running the lumen/sq ft calculation I found here and 6 would be decent and 8 would be better.

I could taper back to 4 or 6 8fters.

Garage is finished, painted, have easy access to attic (minus removing boxes/panels to get to above ceiling space) , panel is located on exterior wall.

General work and restoration in the garage with plans to do fab and welding, table saw, 1.5 HP DP, 1 HP grinder.

I do need more circuits for more than my stupid one outlet so I will probably have to have all of this completed at one time.

Edit: ceilings are 9.5ft

 

[pattenp]

Whoa Nellie.... A 4 lamp F32T8 fixture pulls right at 1 amp max. You only use the ballast input current to size the circuit. Eight of those fixtures will need 8 amps not 16 amps.

 

[Mr. Brooks]

Yeah that's what I was reading as well. 2 lamp 4 ft ones at HD read .8 with somewhat crappy ballast so I have heard.

 

[pattenp]

A 2 lamp F32T8 ballast should be just at .5 amp or less.

 

[shooting4life]

A 2 lamp F32T8 ballast should be just at .5 amp or less.

I measured my 2 lamp f32t8 $18 HD lights the other day and came in just under .5 amps per light.

 

[sands35]

The OP said 8' tubes, not 4' tubes. But he did say t8f32. I assumed 8' tubes which are basically 2x the watts.

Regardless, the math is pretty basic depending on what he ends up buying. If it was me, I'd run a new circuit anyway. But I'd buy the fixtures so I knew what watt draw to plan for.

 

[hoffman912]

not to hijack, but i have a similar question. I am pregaming and figuring out how to best wire the garage. I have an old garage, no ceiling but 4 beams going across the top where the ceiling would be.

I am planing four 4 bulb t8 fixtures run across each beam, daisey chained in one series to an outlet at the end of each beam (so 4 fixtures plugged into one outlet x4 = 16 total fixtures in 4 total outlets). the plan was to have this all on one switch. all lighting on one dedicated circut, separate from garage door opener or wall or any other ceiling outlets.

here is the fixture i am planning on getting
http://www.homedepot.com/p/Lithonia...ty-Fluorescent-Shoplight-1284GRD-RE/202968125

can i run them all on one 20A breaker, or is that too much and do i need to back it down to 2X 20A or 1X30A?

 

[pattenp]

hoffman, one fixture should pull about 1 amp. So you'll be at 16A, which is the max that should be put on a 20A circuit. The circuit should be loaded at no more than 80%. You could do 2 15A circuits or 2 20A. You shouldn't do a 30A circuit for lighting.

 

[hoffman912]

thanks! how do you know each should be 1 amp? and out of morbid curiosity why shouldn't someone do a 30A lighting circuit?

 

[Mr. Brooks]

Update on my lighting...

Went with 3 $40 8ft t8 lithonia fixtures in a "U" pattern until I can get the rest of the electrical completed.

At 1 amp each, I should be good on that circuit.

Still impressed with the output from 12 6500k t8s.

 

[pattenp]

A typical 4 lamp F32T8 ballast uses right at 1A or less.

As far as putting lighting on a 30A circuit this is why not....

210.23(B) 30-Ampere Branch Circuits. A 30-ampere branch circuit
shall be permitted to supply fixed lighting units with
heavy-duty lampholders in other than a dwelling unit(s) or
utilization equipment in any occupancy.

I know a detached garage or shop is not a dwelling, but usually if it's residential it's not allowed. Check with your local building inspector.

thanks! how do you know each should be 1 amp? and out of morbid curiosity why shouldn't someone do a 30A lighting circuit?

 

[hoffman912]

Thanks! sorry if that was a dumb question, just trying to understand the ins and outs and logic.

 

[600SL]

Update on my lighting...

Went with 3 $40 8ft t8 lithonia fixtures in a "U" pattern until I can get the rest of the electrical completed.

At 1 amp each, I should be good on that circuit.

Still impressed with the output from 12 6500k t8s.

Any pictures

How big is this garage. I went with 11 8ft 4 bulb T8 fixtures for a 28' x 30' x 10' garage. I'm beginning to worry I put in too much. Comes out to about 110 cf. Light come on in about 10 days. I will know then.

 

[Mr. Brooks]

Yeah ended up with 12 total bulbs and garage is 19.5X20X9.5. Could use a couple more, but might just have a couple 4ft as task lighting.

No pics due to the mess that it is in. I will try to clean it up and snap some shots. Im very excited about finally have more than one light in there for sure!

Oh and people will tell you...can never have too much.

 

[600SL]

Oh and people will tell you...can never have too much.

Don't I know it see my thread:

http://www.garagejournal.com/forum/showthread.php?t=231499

I also believe good lighting may be something we can get too used to. Could be like ***. Who knows I will find out shortly.

 

[shooting4life]

Yeah ended up with 12 total bulbs and garage is 19.5X20X9.5. Could use a couple more, but might just have a couple 4ft as task lighting.

No pics due to the mess that it is in. I will try to clean it up and snap some shots. Im very excited about finally have more than one light in there for sure!

Oh and people will tell you...can never have too much.

I agree, once you start working in your garage and you start to see shadows you realize where you still need more lights. I have 9 two bulb t8 4 footers in my 18x23 garage, I realized I cast a shadow on my bench when reloading, so I added three more lights above my bench, now no shadows.