About 5 years ago I installed a bunch of fluorescent light fixtures in my shop. They all used the 4 foot bulbs that are rated for 34 watts. At the same time I bought a box of 10 bulbs for spares. Now some of the original bulbs are starting to go so I replaced them with my spares. More than half of my spare bulbs are bad. They start OK but flicker on and off continuously. When I hit a good bulb, they work OK so the fixture is good.
Do fluorescent bulbs die with age even when not used? I stored them next to a heating duct. In the winter they are warmed to perhaps 130 degrees F. Would this have an effect?
They are Philips Con-O-Watt Cool White bulbs.