Recently went through a detailed review of the design of Telehouse Docklands. The UPS service is in fact based on house high-voltage DC. Inverters or converters are installed to meet customer requirements of voltage, frequency, etc. Batteries can carry the original full load for something like 18 hours, giving ample time to fix the generators (grin). The site was originally christened by some Japanese banks who wanted disaster recover for a building full of 3090s, which use 415 Hz power, btw. The mainframe biz didn't make it, so Telehouse started looking around for folks who wanted really killer facilities. They are *extremely* impressive. (better than some Mil-spec places!) The power system has 3 generators available at all times, only two of which are required to carry the original rated load (which was huge by current standards). There is space for a 4th if required. The building has 3 disjoint cooling loops with redundant pumps. The house power risers are huge floating buss-bars in 2 disjoint risers, each carries 2 independent rails ("A and B"). The building is Faraday-shielded because that far down the Thames, the ships go to full power on their radars and there are interesting EMI problems if you don't take care. The exterior glass, which is largely ornimental, is mylar-blast-coated. The recent Docklands bombing was right down the street and "nothing happened". The building AC is fed from 3 distinct locations on the power grid through disjoint entrances, and there are 4 entrances for fiber into the building, all going different directions. There is continuous video surveillance available for spaces, and there is a generator engineer on-site 24x365 (big problem if the generator doesn't start!). They have a run-tank rated for at least a week at full load. Self-contained drinking water and other needs for self-contained full support of the onsite staff. This is a very, very impresive building!!! Interestingly, if you build it like this ab initio, it is cheaper than doing much less after the fact by a LOT. -Mike O'Dell