The Cree ur series is a possible choice

david, thanks. The Cree replacements look easier to install than the ones I was looking at, but at about.double the price, It will probably be worth the extra cost due to ease of installation and Cree dependability.

It will be far more cost effective to put in some program-start T8 ballasts and new tubes. If the current ballasts are instant-start, you need to replace the sockets (tombstones) too. You will have lower lifetime cost, maybe even lower operating cost, but it will be close. You will likely have a greater choice of color temperature and better color rendering. You can adjust the amount of light output by choosing a low, normal or high ballast factor. Light output by the Cree retrofit looks very high, so you might not be able to quite match that. I am not sure.

If you are used to T12 with magnetic ballasts, it is world away to go to T8 with good ballasts and tubes. Yes, the lumens that you get out of the LEDs are directional, so you might get more out of them, on the other hand, depending on your luminaire design, the retrofits might not work well with them.

I finally replaced the four 2 foot T12 lights in my kitchen with Cree UR 2-24's. The installation was easy, but I had to get two self tapping screws for installation in these 56 year old luminaires. The new lights are much brighter than the old lights, which were not bright enough. They are maybe too bright. Is there an easy way to install a dimmer without rewiring from the switch? The Cree UR's are set up for dimming. There are only two wires going into the luminaires from one switch.

Probably not. Check if you have a neutral.

davidtay, thanks for your response. There are two black wires. (This is a not normal house from the 50's.) I marked the one that was connected to the white wire on the old ballast and connected it to the white on the led driver. There was no ground wire visible inside the fixture. After a couple days with the new led's, they seem only a little too bright. I plan to unplug one of the four tubes to see how that looks. Elsewhere, I have led replacement bulbs that are dimmable from regular dimmers, but I guess it is a different situation with the Cree UR's and a regular dimmer would not work.

You need a step dimmer at the very least. There are wiring diagrams showing how a dimmer could be hooked up and how to dim below 50% on the Cree website.

2 black wires? It might be best to have an electrician check things out.