Re: Aircon and networks
I can't remember, it was 30+ years ago, and I was not on the operations side of the support staff, but I'll bet that the main breaker was a "must only be operated by qualified staff", and that they didn't have resident electricians to do that.
Mainframes back then drew quite significant amounts of power, and even then, some facilities were outsourced. Big UPSs were quite novel, and probably weren't as sophisticated as they are now.