In my kitchen, there are 5 halogen lamps, connected in parallel to a 12VAC transformer. The bulbs have rated life of 2000h, but I seem to be getting only about 60 hours out of them.
I measured the voltage at the terminals of the transformer to be 11.9VAC. The fixtures are well ventilated, I do not power-cycle them excessively and the rest of the devices in the household work just fine (my fluorescent bulbs are into their 5th year). I take care not to touch the bulbs with my oily hands when installing.
What could the problem be? A collegue suggested adding a voltage rectifier, but I believe the root problem is something else than the alternating current? Plus those guys seem to have some complicated chemistry going on inside them.