I was going to replace the fluorescent T12 fixtures around my house with T8 fixtures, but I noticed that the T8 bulbs seem to fit just fine into the T12 fixtures. It seems like I could save myself a few bucks and maybe some hassle if I just replace the ballasts instead of replacing the entire fixtures. Plus, I could make sure to buy higher-efficiency or higher-quality ballasts instead of just using whatever mystery ballasts come with the fluorescent fixtures at the home improvement store. Is there anything wrong with this plan?
Replace ballast and lamps, and for extra savings, on a four tube per bay fixture, get a 3-lamp ballast and run only three tubes.
The extra efficiency of the smaller tube plus high-frequency electronic ballast means that three T-8 tubes can put out nearly the same light as four T-12 tubes.
The ballast tends to be a lot smaller, and weigh much less than the t-12 ballasts.
Typical wiring for three tube T-8 electronic ballast.
And useful push-in wiring connectors for doing the rewire. These are Gardner Bender PushGard, others are available and much better than wire nuts for dealing with the small 18-20ga wire used in the fixtures.
A complete building rewire from four T12 to three T8 tubes per fixture eliminated 38 tubes and at 32W each, was a savings of 1216 Watts in power reduction if you only count tube elimination and not also ballast efficiency over mangetic (est. 10-15w per ballast replaced). PLUS, NO FLICKER! For someone with fast vision, not seeing 60Hz flicker in the peripheral vision was almost worth more than the power savings.
Nope, this is done all the time.
Just change the ballast and lamps.
Pay close attention to the wiring diagram on the ballast as the new electronic T8 ballast are wired quite differently from the old magnetic T12 ballasts.