I've seen 10bT Ethernet run over BARB WIRE. The protocol is amazingly bulletproof. 75 feet is a short run, and 12mb/s is dead slow. you can get away with the cheapest cable you can find, or learn to crimp your own ends (it's not hard).
Plenum-rated cable is, if I remember right, a fire-related certification: it won't poison you if you burn it... it comes from office complexes where the cable is run (by the hundreds or thousands) through A/C return above ceiling tiles. If you aren't doing that, it's not worth the money.
Plenum-rated cable is, if I remember right, a fire-related certification: it won't poison you if you burn it... it comes from office complexes where the cable is run (by the hundreds or thousands) through A/C return above ceiling tiles. If you aren't doing that, it's not worth the money.

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