F15T8/XL/SPX65.

The lumen maintenance is comparable to that of standard F32T8 lamps. It's rated to operate on F32T8 ballasts, yet the lamp voltage is the same as regular F15T8, 55v.  In the GE catalog, it says for use with electronic ballasts only and it lists GE UltraMax ballasts for T8 as compatible ones.

http://genet.gelighting.com/LightProducts/Dispatcher?PRODUCTCODE=49489&REQUEST=COMMERCIALSPECPAGE

Their normal F15T8/SPX35 has the same voltage and wattage specs, but does not even list electronic ballasts as compatible ballasts.  I wonder if it will operate properly and live long on T8 ballasts.  All of their normal F15T8s are rated at 7500 hours, with the exception of the first one, which they used to call FE15T8.

http://genet.gelighting.com/LightProducts/Dispatcher?PRODUCTCODE=19645&REQUEST=COMMERCIALSPECPAGE

I noticed the same thing, but I don't know why it is like that. It could be linked to the rated life as it will depend on the ballast. It might just be for marketing reasons as well...

I did ask a local supplier about the SPX35 last fall, and it is quite expensive at 23 dollars each ! I found some F15T8 SP35 at Canadian Tire for 7 $ last winter. I used the latter, even with a lower CRI it is still acceptable and better than the standard warm white or kitchen and bath. As for long life, I have two SP35 in daily use (approx 3-5 hours per day) and we'll see how long they last on chinese preheat chokes.

The classic T8s, that's been around for half of 1900s tend to have a <10,000 hour life.
These are F15T8, F30T8 and the like.

The new T8s that came out in the late 80s last 20,000 to 46,000 hours and these are F17T8(24"), F25T8(36"), F32T8(48" most common), F40T8(60" uncommon).  Perhaps that F15T8 is built on the same electrode technology as new T8s. 

GE no longer makes classic T8s.  They're "Manufactured FOR GE in China" by a contractor.

The new T8s are Made by GE Lighting in USA, Canada or Hungary.

Most likely the electrical specs didn't changed in reality as much, only the publishing got "greener"...
But one difference may be there: The design modification may have as a consequence an increase of the ignition voltage, going above the voltage regular magnetic ballasts (mainly RS, but lower energy chokes with some weaker starters as well) could deliver...
I guess series choke preheater with an electcronic starter would work still fine...

I have not seen any Chinese GE F15T8's but I see the Indonesian ones, and the Hungarian ones.

I DO have 3 daylight colored Sylvania lamps made for these solid state ballasts and I had used them a good while until I move where I am now. They seemed to work fine with no unusual aging or ballast overheating.   They ARE brighter than the regular T8's and right now I have them on the desk in one of the 2 dual lamp fixtures on the desk....you can't have too much light when writing letters with a fountain pen.


Powell

@Luminaire, GE actually makes most of the classic preheat T8s in Hungary. Only the halophosphate F15T8s are made by someone in Indonesia for GE. All of the modern electronic T8s are now made in the USA, the Canadian plant closed in September 2010.

Anyway, yup I have seen the electronic F15T8 lamp, they are mostly used in small refrigation equipment for soft drinks around the checkouts in supermarkets. If I get ahold of one of these, I will try it on a preheat ballast.

@Luminaire, GE actually makes most of the classic preheat T8s in Hungary. Only the halophosphate F15T8s are made by someone in Indonesia for GE.

Really? Most of 18" and under GE branded LFLs I can find in department stores here are not even made by GE.  They're mostly "Manufactured for GE Consumer & Industrial in China".  I have a 90s F15T8/BLB made in USA, but new ones are China rebadge.

I'm not even sure if they're contract manufactured or mere custom relabel. 

Regarding the "Electronic Ballasts Only" statement - my guess would be that the lamps will work just fine with appropriately rated magnetic ballasts - but that the manufacturer isn't going to guarantee that they'll last the rated number of hours unless a suitable electronic ballast is used.

Provided electronic starters are used on the magnetic ballast, I can't see there being any real difference in lamp life though, not unless you live in an area with inordinately high line voltage anyway, which might result in the tube being slightly overdriven.

I could be miles and miles off the mark - but that would be my first thoughts.

@Zelandeth: There are few aspect, what might shorten the lamp life on mains frequency compare to HF electronic ballast, however I have no clue to what extent:
- The arc extinction and reignition around each current zero-cross mean internal surge, what may wear the lamp more then the HF ballast. The HF operate on so high frequency, then the ionization does not have enough time to decay during the HF current zero cross, so no reignition is necessary at all.
- Electronic ballast operate at lower arc current, at the same time with lower crest factor what mean less electrode load.
- On lamp for "HF electronic only" ballast the lamp ignition and AC zero-cross reignition spike voltages are not necessary controlled, so may be too high for regular magnetic ballast setup. This is, because the high voltage for ignition is easilly achievable with electronic ballasts and the periodic reignition is not necessary with HF operation at all.  Note, then "electronic only" T5HE/HO have problems on classic magnetic ballast setup: The starter interfere with the lamp reignition, longer PL-L are "just on the border".

So, I wonder what kind of life I can expect from regular F15T8 if they were operated on an electronic ballast.