After performing some experiments with European Philips TL-D 32w Eco tubes on North American 2 lamp F40T12 fluorescent tube ballasts, I am starting to conclude that the 32w tubes have an arc voltage drop that is between that of a North American F34T12 and a full power F40T12 fluorescent tube and a European full power F36T8. After noticing that my preheat ballasts were running a little hotter than normal, I am wondering if any Philips TL-D Eco tubes have caused older European fluorescent choke ballasts to fail even though modern choke ballasts are better able to handle tubes with slightly lower arc voltage drops.