By Stan Walerczyk
Several times in the past I have stated that highest lumen fluorescent T8s, extra long life T8s, LED lightbars and LED troffer kits are better than TLEDs, but some projects have changed my mind. However, there are still some considerable issues with TLEDs.
I specified a large retrofit for a California county in 2007. The majority of fixtures were 2×4 18 cell 3F34T12 parabolic troffers, which were retrofitted with an upscale kit, 2 3100 lumen 32W F32T8 850 lamps and high performance .77 BF instant start ballast, which consumes 48W. There is a building time clock system, so the maximum annual hours of operation is 3000. The county wants to do a re-retrofit with LED troffer kits and controls, but even with decent rebates and a high KWH rate of $.18, the payback would be close to 10 years, which is way too long for them. The only options with decent paybacks keep existing ballasts with 2 25W fluorescent F32T8s, 1 high lumen 32W F32T8s, or 1 or 2 TLEDs. Plus these options do not trigger California’s Title 24, which saves considerable time and money. Even though TLEDs cost more than fluorescent, more wattage can be saved with TLEDs, and certain people at the county want to go with LED. I have seen pricing as low as $12 in decent quantities on TLEDs designed to work with T8 electronic ballasts.
Since these ballasts have reached half of their rated life, extra long life fluorescent T8s are not that beneficial. When these ballasts start to burn out in significant quantities, it will be an LED or another version of the solid state lighting (SSL) world.
A few manufacturers of TLEDs designed to work with electronic T8 ballasts stated that since ballasts do not provide the high open circuit initial voltage for TLEDs, like they have to for fluorescent and the operating wattage is lower with TLEDs, ballasts can last longer with TLEDs. I am waiting to get feedback from the Department of Energy and ballast manufacturers on this issue.
I have also been told that the system wattage with TLEDs is the same with generic and high performance electronic ballasts that have the identical BF. Although some organizations told me that they would do some testing, that has not happened yet. If any distributor or contractor would like to test this with even a clamp-on amp meter and let me know, that would be greatly appreciated.
Now, some concerns about specific types of TLEDs.
Ones that are designed to work with electronic fluorescent ballasts may only work with instant start ballasts and lamp holders that have two input jacks. Even if the ballasts are instant start, some older and generic versions may not work. The color tone can vary with different ballasts. Some rebate organizations do not provide rebates on these TLEDs. I have recently heard that one major manufacturer of TLEDs for T8 electronic ballasts stopped shipping until some issues have been resolved.
There are significant wiring concerns with hardwired TLEDs. For example, I have seen numerous projects where the contractors or end-customers used some of the wiring that went between lamp holders and ballast to save time with wire nuts. But the wrong color and/or gauge of wire can be an electrical code violation. With 277V going to lamp holders, some organizations may require electricians to change lamps.
The best TLEDs may have their own separated driver, which can go in the ballast compartment. But LED lightbars with their own driver in the ballast compartment is probably better.
A colleague in the army forwarded me a marketing piece from one TLED manufacturer, which had a lot of hype. It stated that F32T8s only have 2600 initial lumens, while good ones have 3100 lumens. It also stated that there is no loss of lumens from TLEDs in lensed or other fixtures, which is incorrect, because about 20% will be lost from fixture efficiency and thermal losses. When I see this type of marketing hype, I want nothing to do with these companies. If distributors and contractors also tell manufacturers that they do not like marketing hype, manufacturers would probably do less of it, which would be a great improvement.
Please send any comments or questions on this column to firstname.lastname@example.org, or comment below.Tagged with Exclusive Feature, LED, lighting, tED