Lighting, Light Fixtures, Ceiling and Exhaust Fans - New Fluorescent Fixtures - Tubes Very Short Life

Ever since installing three Cooper Lighting fixtures from Home Depot in my basement, I have not been able to get more than a few months life from tubes. This is in all three fixtures, two of which are wired in parallel off the same switch, and the other of which is by itself off another switch. The fixtures hold four 4 ft. tubes each. I went back to HD and they offered me replacement fixtures but I didn't want to re-do the whole installation (many hours), so they gave me all new ballasts out of three of the same fixtures, new on the shelf that they just gutted & scrapped. I wired in the new ballasts exactly as the originals, and the fixtures worked fine, but again within a month the tubes started going black at the ends and dying. These were fairly inexpensive fixtures; is it simply that you get what you pay for and I need better fixtures? I hope not. These were the only ones at HD that fit right up between your floor joists in the basement, above the suspended ceiling.
Could it be that I'm using the wrong tubes? The fixtures have a sticker on them specifying that only tube type something (like WF40 or something) be used. Are these things so sensitive to the type of tube that the ballasts are effected? I've tried every type of 40W tube, of which there are umpteen.
Help!
We home school and this is our classroom, but my wife is about to give up if I don't give her some consistent light. This is costing me a fortune in tubular glass, mercury, and metal.
Thanks.

I too had similar problems with fluorescent lighting in my kitchen and had replaced the ballast with no satisfying results. I finally changed the brand of bulb I was using. I am in no way promoting any brands and have no connections to either company, but in my personal case, I was using a Phillips and switched to GE. It seemed to work.

definately try a different brand of lamp. it may make all the difference in the world.

also, if you have use of a voltmeter, take a voltage reading. Over or under voltage can shorten lamp life considerably. Also, make sure all electrical joints are made well.

Where are you measuring the voltage: supplying the fixture?, where the lamp pins plug in?, somewhere else?

How much over or under is acceptqble?

Thanks,

voltage to the fixture. DO NOT measure the sockets. Some ballasts run up to 600 volts or so on start up.

as with all things if this is a 120 volt system, you should have between 132 and 108 volts (120 volts +/- 10%).

another thing that has been a problem in lighting is electronic ballasts. Generallt I like them but for the past couple years there has been a lot of problems with them. I had one job where we installed a boat load of 2x4 lay-ins. Within 1 month, we had to replace 4 or 5 ballasts and about the same the next month. Manufacturer paid to replace all ballasts as a warranty. Even the ones that had not been replaced yet.

From what I unsderstand, there was/is a bad batch of capacitors floating around and the same manufacturer makes the caps for a very large percentage of the ballasts out there.