© General Electric
George E. Inman and Richard N. Thayer, 1936
demonstrating a fluorescent lamp.
"At one time in development, rival cathode designs from the Inman and Pritchard groups necessitated the intervention of a neutral physicist from GE's Research Lab., who ruled in favor of the Pritchard design."
-- Richard N. Thayer, in an unpublished paper, 1989
Several inventors, including Thomas Edison, explored the use of fluorescent materials in electric lamps during the late 19th and early 20th centuries. Results were not promising. As other designs matured and the tungsten-filament incandescent lamp came to dominate the market, research into fluorescent lamps stayed at a low level. Some researchers doubted that a practical lamp could be made. As co-inventor Richard Thayer recounted years later:
||"Imagine our surprise when we received a report in August 1934 that the laboratory of the General Electric Co. Ltd. in London (no relation to U.S. GE) had made experimental green fluorescent lamps with an efficiency of 35 lumens per watt -- three times that of household-sized incandescent lamps! We thought that the decimal point must be wrong, and that the correct figure was 3.5 lpw. But further European information was confirming, and in December 1934 we began U.S. development."
George Inman headed a group at GE's Nela Park facility (in Cleveland) that began looking into fluorescent lamp development. To save time, he adopted the design of an existing tubular incandescent lamp in order to make use of available production equipment and lamp parts. Speed was important. Not only were European competitors already working, but American companies Westinghouse and Sylvania were also beginning to look at fluorescents.
A second GE group was set up under Philip J. Pritchard "to adapt, develop, and build automatic equipment to manufacture the lamp." Different opinions about various technical details like cathode design caused friction between the rival teams, as Thayer noted above. Also, fluorescent lamps were more complicated devices than simple incandescent lamps. This meant that other GE groups (in Schenectady and in Ft. Wayne) assisted in developing ballasts and resolving problems of circuit design.
In 1938, GE began offering fluorescent tubes for sale -- in four sizes. One size from each of the two Nela Park teams, one compromise between those two, and one especially for industrial use. However, the size that ultimately sold best (48 inches, 40 watt) was not introduced until a year later as, "it seemed to us then an impractically large lamp."