i followed a formula from another link equal to 100 lumens per ft and come out to a total of 15.78 bulbs for my shop.
18x25 9ft ceilings. would you do 8 2 bulb fixtures, or 4 4 bulb fixtures?
The eight twin-tube fixtures route is BY FAR preferable. And you could even make an argument for 16 single-tube fixtures.
the price difference isnt much, and i could spread the 2 bulb fixtures out for more of a light spread
That is EXACTLY why the four-tube fixtures are a bad idea. With only 9-foot ceilings to work with, you would need to go well into "overkill" territory in terms of total brightness, in order to keep the illumination reasonably even and balanced.
and also replace them cheaper down the road when the ballasts go out.
Buy quality stuff to start with, and avoid NEEDING to replace them later.
both have light grey reflectors, but the 4 bulbs have an outlet, which will help save in some extra wiring installation and cost.
Actually, it won't.
Per the current NEC, any and ALL 120V electrical outlets installed in a garage MUST have GFCI protection, even ones mounted 8-10 feet in the air on a ceiling. That not only ups the ante to PROPERLY install such plug-in "shop lights", it very well might also lead to operational problems (many fluorescent fixtures do NOT behave well when run off GFCIs, and vice versa).
Personally, I would not use either of those fixtures; and I would strongly caution you against them as well. Chain-hung fixtures such as those are usually NOT rated for direct surface mounting, due to heat issues. And hanging the lights from chains (thus lowering their installed height) is the LAST thing you want to do when you only have nine feet of ceiling height to start with.
http://keystoneballast.com/files/product_docs/KTEB-432RIS-1-TP_spec_sheet.pdf
I just bought the 4 bulb fixture and noticed that the bulbs seem dim compared to my other fixtures.
The ballast it uses is a Keystone KTEB-432RIS-1TP. It has a ballast factor of .8 when used with 4 T8 Bulbs. Basically, a 2800 lumen lamp will be putting our 2240 lumens.
Yeah, but the upside is, those tubes are going to last halfway to forever.
I personally would go with 2 bulb fixtures for more even light distribution, and less shadowing.
Agreed.
I also would put 4 fixtures on one switch and 4 on a second. That way if you are just running in to grab something quick, you are not starting all the lights. Saves electricity, and makes the lights last longer.
I agree with he basic premise; but I would take it further. One or two fixtures on the "Walk Through" switch; 35-40% of the rest on the "Main Lighting 1" switch; the rest on the "Main Lighting 2" switch. Voila! Three selectable levels of main lighting, as needed.
IMHO, outlets on fixtures are about like extension cords, they are meant for temporary use only.
Also agreed.
i guess i just need to go buy one and inspect it. out of the budget lights, those 2 bulb from home depot seem way better quality than the utiilitech stuff at lowes.
You don't need to spend a ton of money to get some MUCH more appropriate fixtures. I've posted these examples several times:
http://www.homedepot.com/p/Lithonia-Lighting-2-Light-Utility-Light-3348-2L32W-WRAP/100654395
They're cheap; they look half-decent; they can be strung together in more-or-less continuous "strips" when appropriate; the polycarbonate lens both helps to evenly distribute the light and provides some impact protection; and the 4-foot size makes placing them where you really need them relatively easy. There's also a matching two-foot version:
http://www.homedepot.com/p/Lithonia...hite-Fluorescent-Light-Fixture-3324/202192968
if you need to fit into really tight spots, or fill out a specific-length run.
sorry for the rambling on. now that i look back on their site they have a 6 bulb "high bay" fixture with the nice chrome reflectors for 79 bucks. 3 of those is only 240.
WHOA, NELLIE!
Now you're going even further off the rails.
With only 9-foot ceilings you do NOT want to go anywhere near anything denoted as a "High Bay" fixture. That will only make your light-distribution problems that much WORSE.
while i am not wanting to cheap out,
No offense; but it sounds to me like that is EXACTLY what you are trying to do, mostly in the form of trying to "get away with" using far too few fixtures to PROPERLY illuminate the space.
it looks like going the cheap route will cause me to buy more lights to make up for cheap ballasts anyway. my only concern with the high bays is i see people recommend them for 12ft + ceilings.
I just posted the following in another thread; but it also applies (in spades!) to you:
Please understand this: Regardless of any other considerations, your "limiting factor" is your ceiling height. Your inter-fixture spacing will be determined almost solely by that dimension, at least if you wish to maintain reasonably even coverage at working height. Further, in order to ensure that reasonably even coverage, the spacing WILL be close enough that even single-tube fixtures are likely to be adequate, on an overall lumens/ft.^2 basis; and the common 4-foot twin-tube fixtures will surely provide MORE light than you really need. Going to four-tube fixtures (especially ones which limit their side-spread like troffers do) will NOT permit you to use fewer fixtures; it will only make the hot spots hotter, relative to the shadow areas.
those are commerical lithonia. bound to have a better quality ballast.
Not necessarily. "Commercial" ballasts do not need to meet the EMI/RFI standards required in residential applications; and as a result, they can be a nighmare when so misapplied.
