On 24 Jun 2008 03:16:08 GMT, ddl@danlan.*com (Dan Lanciani) wrote:

In article , (Paul M. Eldridge) writes:
| On 22 Jun 2008 17:16:51 GMT, ddl@danlan.*com (Dan Lanciani) wrote:
|
| 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.

I get kind of confused when several variables change at once.
Assume that I use the same ballasts I was using 20-30 years ago
and also assume that I don't like the lower illumination from the
60W tubes so I use the current more expensive 75W tubes. (Both
assumptions happen to reflect reality. How does my energy usage
today compare to my usage when I could get the cheap 75W cool white
tubes?


Hi Dan,

If your 75-watt replacement tubes are driven by the fixture's original
ballast, wattage remains the same -- again, about 180-watts in total.


| 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.

Can I get energy saving magnetic ballasts to drive 75W tubes at higher
efficiency or do they depend on using the 60W tubes?


You can; as is true of your current ballast, energy saving magnetic
ballasts are compatible with both 60 and 75-watt lamps. However, if
you plan to replace the ballast, you might as well switch to an
electronic version and pop in a couple T8 tubes; the benefits a

* 40% energy savings (110-watts versus 180-watts)
* 50% longer lamp life (18,000 hours versus 12,000 hours)
* cooler operation (potentially helpful in warmer climates)
* silent operation (no annoying ballast hum)
* no flicker (important if you work with some types of machinery)
* typically better colour rendering (improved light quality)
* better lumen maintenance (more light over the life of the tube)
* typically better cold weather performance (starting down to 0F)
* better long-term availability of replacement lamps (???)

A 75-watt F96T12 + standard magnetic ballast is the technical
equivalent of a 1978 Ford Granada. It may have been considered a good
performer in its day (** snicker **), but thirty years later we've
thankfully moved the goal posts a little further.

Cheers,
Paul