The master (Sherlock Holmes) said that it is folly to theorize before you
have all the facts.
I now have the facts.
The light bank used at the college consists of eight, inexpensive undercounter
FL fixtures with the plasic removed, glued inside a wooden box on legs and
wired in parallel.
The light bank I use at home was more carefully constructed according to plans
published by the Pallado Co. using special ballasts and uses six bulbs
The bulbs in both units are Sylvania 350 Blacklight F15T8/350Bl 15 Watt.
I used a Triplet Laboratory Type AC Voltmeter/Wattmeter and a Triplet
Laboratory Type Foot-Candle Meter for measurements.
The light meter probe was positioned in the center of the light banks and
10 cm. from the tops of the bulbs.
Results:
College Light Bank
123 Volts AC 100 Watts 210 Foot-Candles (after warmup)
Home Light Bank
124 Volts Ac 115 Watts 150 Foot-Candles (after warmup)
As I mentioned, the bulbs in the light bank at home are 2-3 years old.
Therefore, I put new bulbs in the light bank at home. Here is what happened:
Home Light Bank (New Bulbs)
124 Volts AC 120 Watts 200 Foot-Candles (after warmup)
Conclusion: Even though they were not used a lot, these bulbs do age. Either
that or the new bulbs are designed to produce more light (note
the wattage increase). In any case, there is enough difference
in the light output that I think I can blame the light bank rather
than the ammonium dichromate; nevertheless, Judy's comment about
a loss of speed with old AmDi suggests that two factors may be
at work here.
Bob Schramm