This was not a building wide problem; apparently it did serve to find
the failed UPSes in a few places. The building management does these
tests several times a year, and at least to the one colo where we had
visibility to the building electrical service, we saw the same outages
we always see during such a test.
It is also worth noting, that I only saw one of about 60 BGP sessions
across the Seattle-IX (which is in the building) reset at the time of
the work.
John