Here's a Ottlite 14w Visionsaver Plus lamp that's intended to run in a electronic ballasted Ottlite desk lamp but runs fine on 15w preheat ballasts. The plastic sockets fit standard T5 lampholders so retrofitting a regular striplight for these is a snap.
The reason for T4 instead of T5 is not the cost, as on such small tubes the processing (part not dependent on product size, but on it's complexity) is way more expensive then the raw material and the shorter tube mean the assembly is more complex then standard - so i guess this would eve be more expensive to make then standard T5.
Thinner tube allow to boost efficacy, if you are able to keep the mercury pressure on the optimum level on such elevated temperature (so with the use of amalgam concept). This is a try to make the more efficient T4 tube compatible with fixtures designed for T5. The tube has to be shorter, as thinner tube yield higher voltage drop per unit length.
The question is, how well is the design done, so if the possible efficacy increase is not compromised by the use of poor quality materials (e.g. phosphor, amalgam,...)
Eurolux manufactures T4 fluorescents with the usual metal end caps.
They are available in 8W and 20W, with triphosphors coating and are no more efficient then the halophosphors tubes (65 lm/w for the 20W and 48.75 lm/w for the 8W).
They have also only 6000 hours life on IS electronic ballast.
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Thinner tube allow to boost efficacy, if you are able to keep the mercury pressure on the optimum level on such elevated temperature (so with the use of amalgam concept). This is a try to make the more efficient T4 tube compatible with fixtures designed for T5. The tube has to be shorter, as thinner tube yield higher voltage drop per unit length.
The question is, how well is the design done, so if the possible efficacy increase is not compromised by the use of poor quality materials (e.g. phosphor, amalgam,...)
They are available in 8W and 20W, with triphosphors coating and are no more efficient then the halophosphors tubes (65 lm/w for the 20W and 48.75 lm/w for the 8W).
They have also only 6000 hours life on IS electronic ballast.