Rare! High wattage incandescent systems that are still in use these days amaze me. I used to relamp 750w incandescents at an auditorium years ago.

My middle school built in 1965 in the gym and stage room had a system like this, but the fixtures were more of a high bay style (without the ballast box) and had some wire cover (flat style not the saggy style like this one) All of the big fixtures had frosted probably 500 or even 1000 watt lamps and one row had smaller reflectors with smaller lamps and they were clear instead of frosted but one did get replaced with a frost one day. I remember i think 2 or 3 times one of the lights got hit by a ball and broke the lamps! LOL

Very nice! Just what my school had until a few years ago. I would love to get a hold of all those fixtures I could!