So what is the operational difference between a T12, and T-8? (Other than lamp diameter) What creates this low life cycle when a customer mis-matches the lamp - which works fine for some time - but still works none the less....
Starting? (Both Rapid Start - one electronic the other magnetic - both still available for each)
Voltage? (120-277 universal input if not specified...) Output voltage????? (unknown)
Current? (unknown)
Current correction value? (unknown)
Wattage - 40W vs. 32W But how does that change anything????
I do believe I have an answer as to why you have a shortened life on your bulbs in this poor installation you have stumbled on. you want to know why the bulbs deteriorate at a higher rate when installed in the wrong ballast. Jon is correct but the term I believe you are actually after is Ballast factor.
I cut and pasted this from "the Advanced Lighting Guidelines: 1993 (Second Edition), originally published by the California Energy Commission."
Ballast Factor
One of the most important ballast parameters for the lighting designer/engineer is the ballast factor. The ballast factor is needed to determine the light output for a particular lamp-ballast system. Ballast factor is a measure of the actual lumen output for a specific lamp-ballast system relative to the rated lumen output measured with a reference ballast under ANSI test conditions (open air at 25 degrees C [77 degrees F]). An ANSI ballast for standard 40-watt F40T12 lamps requires a ballast factor of 0.95; the same ballast has a ballast factor of 0.87 for 34-watt energy saving F40T12 lamps. However, many ballasts are available with either high (conforming to the ANSI specifications) or low ballast factors (70 to 75%). It is important to note that the ballast factor value is not simply a characteristic of the ballast, but of the lamp-ballast system. Ballasts that can operate more than one type of lamp (e.g., the 40-watt F40 ballast can operate either 40-watt F40T12, 34-watt F40T12, or 40-watt F40T10 lamps) will generally have a different ballast factor for each combination (e.g., 95%, <95%, and >95%, respectively).
Ballast factor is not a measure of energy efficiency. Although a lower ballast factor reduces lamp lumen output, it also consumes proportionally less input power. As such, careful selection of a lamp-ballast system with a specific ballast factor allows designers to better minimize energy use by "tuning" the lighting levels in the space. For example, in new construction, high ballast factors are generally best, since fewer luminaires will be required to meet the light level requirements. In retrofit applications or in areas with less critical visual tasks, such as aisles and hallways, lower ballast factor ballasts may be more appropriate.
To avoid a drastic reduction in lamp life low ballast factor ballasts (<70%) should operate lamps in rapid start mode only. This is particularly relevant for 32-watt F32T8 lamps operated at high frequency.
Finding the ballast factor for lamp-ballast combinations may not be easy, as few ballast manufacturers provide this information in their catalogs. However, if the input power for a particular lamp-ballast system is known (usually found in catalogs) an estimate of the ballast factor is possible.
