In the Alternative energy arena, Trace Engineering makes a 4000 and 5500 watt 48 VDC sine wave inverter that supports stacking of two inverters to double the capacity/reliability. It's probably not designed to be rackmountable though. For smaller applications, Exeltech makes physically compact solid state sine wave inverters ranging from 250 - 6000 watts. If your running AC equipment with non-switching type power supplies, like CSU/DSU's, monitors or MUXes watch out for any inverter that does not generate a true sine wave. Square waves and modified sine waves can fry such equipment. And Yes, you do need hefty wiring on DC equipment due to the voltage drop created when transmitting high current at low voltage. I have a 400 amp hour battery bank in my van with a 1200 watt inverter mounted about 10 feet away and I used 2/0 (that's pronounced 2 ought - heaver than 0 gauge) wire for a proper connection. There are formulas for calculation of the correct wire gauge. Heavy wire that is flexible enough to be routed around corners and through racks is made of braided conductors and is commonly available from welding suppliers. Trace Engineering can be reached at 206-435-8826. Exeltech can be reached at 817-595-4969. I could provide lists of vendors of such equipment if that is appropiate. Rob