it would be cool to install this and make the inner lamp have a different ballast and the outer 2 use the existing ballast and use 2 circuits so you can control the light level
They did that with the F40T12 3-lamp parabolic troffers in the computer room at my old elementary school. It was built in the early 90s so when the school systems upgraded the schools to T8, the lights weren't seen as "outdated" yet. The lights in the library and cafeteria were massive 4X4 6 lamp T12 fixtures. they were replaced by pairs of 3-lamp T8 troffers like this one the year after I left the school since the milk white lenses kept breaking from being so hard to handle by one person on a ladder. The 400W probe MH high bays in the gym were replaced by motion sensor T8 lights the year after i left as well.
The hallways are still lit with 1X4 2-lamp T12 troffers with milk white drop lenes and the classrooms are lit with 3 lamp wraparound lights. I think the bathrooms (and maybe the two normal staircases) were lit with 1X4 troffers as well but with standard lenses. The winding staircase in the front was lit by i belive MH circle lights with ribbed glass lenses. It was very rare that they were on though. The janitors never bothered turning them on sicne there was a "wall or windows" as i referred to it that follow the winding staircase.
The offices were lit by 2X2 troffers with some sort of parabolic lens. It wasn't a crate like above, rather a lens that had a parabolic affect. I wish I could go back and take pics but I'm going into high school now...
I've never seen a magnetic T8 ballast. I don't know how to tell magnetic from electronic when the ballast is hidden. The corner of the eye thing with the flash patterns doesn't work for me and neither does squinting.
usually I look for a fixture with a missing ballast cover or dead lamps and then know
also cell phone and Ipod cameras usually give you a 60 HZ flicker line whereas electronic ballasts don't
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The hallways are still lit with 1X4 2-lamp T12 troffers with milk white drop lenes and the classrooms are lit with 3 lamp wraparound lights. I think the bathrooms (and maybe the two normal staircases) were lit with 1X4 troffers as well but with standard lenses. The winding staircase in the front was lit by i belive MH circle lights with ribbed glass lenses. It was very rare that they were on though. The janitors never bothered turning them on sicne there was a "wall or windows" as i referred to it that follow the winding staircase.
The offices were lit by 2X2 troffers with some sort of parabolic lens. It wasn't a crate like above, rather a lens that had a parabolic affect. I wish I could go back and take pics but I'm going into high school now...
also cell phone and Ipod cameras usually give you a 60 HZ flicker line whereas electronic ballasts don't
Here's a example of the 60 Hz flicker lines that show up in phone camera/iPod pictures.