Nice design, but I think it is a bit too much.
First thing I suggest is to taka a True-RMS clamp meter and measure the actual current consumption in as many computers as you can. I’ very sure that the measure will be at least half what the plate says. 100 computers for a class room will have slight variations, but the totals will add pretty well if you sample a generic 10% and multiply.
Doing some calculations, I doubt that if we are talking about normal PCs (like Dell Dimension XXX) the individual power consumption could be more than 400 VA. So, we have 40 KVA. One 75 KVA K-type transformer will be more than enough and leave enough room to accommodate variations in the computers, accessories and future grow.
One transformer means only one input breaker.
About the lines, if you are going to share every circuit between two computers it will be more than enough to run number 12 wire. Two times 400 VA add to a current of 7 amps. 85 feet in the worst case is not a problem. I could say that you could even power four computers per line, but let’s give some rest to the wire.
But if you run number 10 wire then you could power four per circuit.
Remember that neutral considerations due to harmonics don’t apply to single circuits, neutral and hot, both number 10, will be more than enough for 1600 VA.
Zig-Zag transformers are a good option too. And, as some other members have noticed, maybe you could put two duplex receptacles per computer, you will need them.
Regards,
Joe.-
