Philips has put up the first streetlamps that use light-emitting diodes (LEDs), which last four times longer than normal street lighting, the Dutch electronics group said on Friday. With 50,000 light hours, LED lamps do not have to be changed for 12 years when lit for an average 11 to 12 hours a day. Because LEDs are made of solid organic materials, they are smaller, more versatile and less vulnerable than today"s glass lamps filled with gases, Philips said. "The lifespan of a streetlamp is no longer limited by the lamp, but by the pole," a Philips spokeswoman said.