Power cabling advice?

Hi all, After reviewing the current status of the power system I have for the hobby systems (7 segments of 240VAC at 20A each, one of which being used by a big airco), I noticed something. I did my best to physically separate the systems from eachother on the network, just to avoid massive burnouts if/when a single system goes BOOM on me. I use AUI ports and -cabling to (DELNI) repeaters, and from a DELNI (a "systems group" in my network), a single 10BaseFL link goes up to the fiber hub in the machine room, which handles all the other stuff etc. However... it just ocurred to me that even though I did that, I still have some sort of a "connection" through the main power lines (3x 500VAC @ 48A/ea) here, so, if an old 11/23 in a BA23 goes smokey on me, it still could kill my (quite expensive) production network stuff through the power system. Does anyone have (serious) ideas on how to fix this (short of requesting three separated power lines from the utilities.. they have a hard time dealing with me as it is ;-) Thanks, Fred (slightly worried)