1. Home
  2. Electronics Design
  3. Efficient Lighting
  4. Page 2

Efficient Lighting

Gas discharge lamps, such as fluorescent lamps, operate at a rated current instead of a rated voltage. Therefore, lamp "families" can be made with different power ratings if they all operate at the same current but have different lengths. The voltage is determined by the lamp length, diameter and fill gas, so otherwise identical lamps of different lengths will draw different amounts of power when operated at the same rated current.

GE makes the following T8 lamps:

17-watt, 24" long 25-watt, 36" long 32-watt, 48" long

Note that due to the different lengths, these lamps CANNOT be interchanged in the same fixture, though it may be possible to operate them on the same ballast.

Ballasts are current sources instead of the more common voltage sources. A single ballast can therefore be designed to operate loads with more than one power rating as long as the different loads operate at the same current. So, one ballast can be made to operate all these different lamps.

Now, in addition to the standard lamps listed above, it is possible to change the buffer gas in a fluorescent lamp to reduce the operating voltage for a given length and diameter and make a so-called "energy saving" version.

GE makes a 28-watt, 4-foot, T8 lamp that is designed to operate on ballasts designed for 32-watt 4-foot lamps. Philips may make a 25-watt, 4-foot lamp using similar techniques, but I cannot confirm that right now. Such a

25-watt lamp should operate on your ballast. However, this should not be confused with the 25-watt 3-foot lamp that is listed on the label of your ballast.

I do not think it is possible to make a 17-watt, 4-foot lamp that has the same operating current as the 32-watt, 4-foot, T8 lamp. Nature has not provided us with a heavy enough rare gas.

--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail: 
replace xxx with vdr in the Reply to: address
or use e-mail address listed at the Web site.

This information is provided for educational purposes only. 
It may not be used in any publication or posted on any Web 
site without written permission.
Reply to
Victor Roberts
Loading thread data ...

My new GE electronic ballasts list T8's in 32, 25 and 17 watt, over a wide voltage range (120 to 277), and the GE ballasts come in one, two, three and four bulb versions. I have not seen a 17 watt bulb in the wild but some big box stores carry the 25 watt versions from Philips.

Richard.

Reply to
Richard

I would guess that's your equivalent of our 2' 18W tube, which is very common in modular ceiling luminares in groups of 3 or 4 (at least in Europe).

--
Andrew Gabriel
Reply to
Andrew Gabriel

Our big box stores in the USA sell a 4' Philips 25 watt T-8 what works to perfection with this GE electronic ballast. I assume GE also offers a T-8 in this size but I have not seen one. This bulb puts out about 5% less output than the same color temperature 32 watt Philips bulb. A great combination if you don't require a warm color temperature. It has an 82 color quality rating.

Richard.

Reply to
Richard

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.