Fluorescent Lights

I did the same at our Church way back when - changing T12's for T8's. Found the best place to buy ballasts was Ebay. 10 packs including shipping for name brand ballasts for cheap. T8's and electronic ballasts sure a nice compared to the old magnetic ballasted T12's.

Thanks TPI-I am using 4 bulb ballasts for 4 bulb fixtures, 2 bulb ballasts for 2 bulb fixtures, etc. Extra cost of 4 bulb vs. 2 bulb ballasts are minimal and replaced as they were original in case we wanted to add bulbs later.

If you're just powering two lamps per fixture on a four lamp ballast, there is a slight penalty over using a two lamp ballast in that fixture. But nowhere near the power of powering four lamps. Usually you can find the specs on the ballast documentation which shows power draw with two, three and four lamps. Usually ballasts driving less lamps than designed for will drive the remaining lamps slightly harder (brighter), and that is in the specs too. Typical ballasts drive lamps to .88 power level or ballast factor. Anything above a "ballast factor" of 1.0 (32 watts for 32 watt lamp)is overdriving the lamp. It is acceptable to overdrive the lamp up to 1.20 without negative consequences. In fact it is often done intentionally, replacing four lamps with two and overdriving the two to 1.20. These are called "high ballast factor."

You are right, the T8 electronic ballasts are a completely different animal from the T12 rapid start magnetic ballasts.

When retrofitting fixtures it is always a good idea to replaces yellowed lenses and clean reflectors. Prismatic lenses are more efficient than white opaque. You can easily gain 20-30% efficiency right there.

Skip, that's what I was thinking and these are electronic ballasts.

Someone told me that he was told,-I know-second hand info.-that it there is no electrical savings as the ballasts are using extra electricity to send power to the missing lights and may cause extra work on the ballasts but I think he was referring to the old type ballasts.

No reason to install more than you need.