On 22 Jun 2008 17:16:51 GMT, ddl@danlan.*com (Dan Lanciani) wrote:

In article s0c7k.232$zE6.219@trnddc02, (James Sweet) writes:
|
|
| In the past few years I've noticed that the commodity F40 and F96 tubes
| at the home centers are once again 40W and 75W respectively, so I assume
| they all now qualify for the good color rendering (or other) exemption
| from the requirements. (Or are they lying about the wattage?)
|
| Dan Lanciani
| ddl@danlan.*com
|
|
| Trichromatic phosphor blends are much more common these days and a lot
| cheaper than they used to be, so you can easily get 40W high CRI lamps.

And 75W F96 tubes, though they cost a little more than the dirt cheap CW
versions did. I guess this is great if you like a high color rendering
index, but I'm still not clear on how it ultimately helped with energy
conservation or efficiency. Now if they had gone on to produce 34W F40
and 60W F96 tubes that put out as much light as the older 40W and 75W
versions I could see the justification for the higer costs, ballast
replacements, and such in the meantime. But as it is, aren't we pretty
much back where we started (from an energy usage point of view)?

Dan Lanciani
ddl@danlan.*com


Hi Dan,

Twenty or thirty years ago, a conventional two-tube F96T12 fixture
would draw about 180-watts. Today, with 60-watt lamps and energy
saving magnetic ballasts, that number falls closer to 135 or
140-watts, so there's been at least some improvement.

In terms of operating efficacy, a 75-watt Sylvania F96T12/D41/ECO
(4,100K/70 CRI) is rated at 6,420 initial lumens and powered by a
standard magnetic-core ballast (0.88 BF), we obtain about 63 lumens
from each watt. A 60-watt Sylvania F96T12/D41/SS/ECO (4,100K/70 CRI)
at 5,600 initial lumens and driven by a newer energy saving magnetic
ballast would bump that up to perhaps 71 or 72 lumens per watt.

Things do improve considerably once you move to T8. A 59-watt
Sylvania F096/841/XP/ECO (4,100K/85 CRI) has a nominal rating of 6,100
lumens and a two tube fixture with a 0.88 BF electronic ballast draws
approximately 110-watts -- that puts us in the range of 97 or 98
lumens per watt.

In addition to better colour rendering and higher system efficacy,
there's also a 50 per cent improvement in lamp life (18,000 hrs.
versus 12,000 at 3 hrs per start), plus no flicker or ballast noise;
lumen maintenance is also notably better at 93 to 95 per cent versus
80 to 85 per cent. As an added bonus, T8s typically offer better cold
weather performance (e.g., Sylvania's F96T8 lamps have a 0F starting
temperature when used with Quictronic ballasts).

Cheers,
Paul