Hi all,
Hope someone can help me.
Using the article from a few month’s back on lighting your shop, I’m trying to track down fixtures that have ballasts with the CBM stamp. According to the article, the CBM ballasts provide 90% of the optimum light (bulb) output, and uses less energy. When I went to my local Depot, and for that matter, contacted two electrical supply houses, no one knew what I was talking about. The one ballast at Depot that had that stamp, I was told, was less efficient than the others.
The fixtures that had the CBM were the 8 footers and the 4-bulb 4-footers. I wanted to avoid using the 8 footers because I anticipate a hassle swapping out the bulbs (storage, disposal, hauling, etc.) – that leaves four footers. I could probably use the 4-bulb 4 footers that are arranged to make an 8-foot fixture, but I want to exhaust my options from a cost standpoint.
For the shop, I reckon it may not be as critical. But I also raise reptiles and those bulbs are $ 18 each. The bulbs get eaten in those cheap $8 shoplights. I’m pitching them as they burn out, or using them for general lighting, and upgrading the animal room lights. So, there, it may truly matter.
My questions are:
1. Really, how important is the CBM stamp? Is there another equivalent stamp (for example, I see CSA on alot of fixtures).
2. Is there any benefit/trick to matching the T’s? Like if I buy T8 fixtures, and use T12 bulbs, does that shorten the life?
3. Why does it seem so hard to find that CBM stamp? It exists, I’ve seen it. Just not on the fixtures I would choose.
Is there any other guidance you guys can give?
thanks abunch,
Joe
Replies
The fixture you want is Lithonia UN296HO, the lamps are F96T12/CW/HO/CT
The fixture is approx 30 bucks at Lowes, bulbs about 5 but cheaper in quantity.
Joe,
In answer to your questions:
1. A CBM rating means that the ballast will drive the lamp at 95% plus or minus 2 1/2% rated light output, and a typical lamp will operate for it's rated life. A non-CBM ballast may drive the lamp at a light output of as low as 50% although about 70% is common, and life can be as much as 50% shorter. A CBM rating is important.
2. Ballast and lamp ratings MUST match. The voltage and current ratings for T8 and T12 lamps are different, and operating a lamp on a ballast designed for a different lamp will affect light output and lamp life.
3. CBM is a ballast rating, not a fixture rating. To determine if a fixture has a CBM rated ballast, remove the fixture pan and look at the ballast. A CBM rated ballast will have a diamond printed on the label with the letters "CBM" printed inside the diamond.
Use a Lithonia UN240 if you want a 4 foot fixture with a CBM ballast.
One final note. A CBM rating is specific to a lamp/ballast combination, and most CBM ratings are based on full wattage lamps. The use of reduced wattage energy saving lamps such as the 34 watt 4 footer or the 60 watt 8 footer will result in a lower light output - about 86% instead of 95%. Not great, but significantly better than a non-CBM ballast.
I wrote the article in FWW.
Jack Lindsey
Edited 4/2/2002 3:06:23 AM ET by none
Edited 4/2/2002 3:26:14 AM ET by none
Hello Jack. I debated writing back about your article, but never got around to it. I manage a hospital facilities department and have worked with lighting issues, energy retrofits, and designers for several years. I am no lighting expert, but have developed opinions about lighting over the past several years of professional time invested in lighting issues. I would (and have) taken a different approach to this in my shop.
I have been using discarded 4 tube 277 volt fixtures for lighting. I started out by installing eight switched receptacles in the ceilng of my shop (24X24). Where I need a fixture I retro-fit a 120V T-8 ballast with a 6' plug. This allows me to install and switch fixtures anywhere in my shop.
Additional benefits are: the light is 30% cheaper, the quality of light is much better, four foot fixtures are much easier to manipulate. I can play the AM radio without interference, my wireless phone works in my shop, and the lights come on when they are cold. These benefits for me greatly outweigh the additional cost for a 120V electronic ballast (about $15). The switched receptacles allow me the flexibility to move the lights anywhere I want with in my shop.
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