Office building with personal computers, terminals, copiers, and other electric office equipment supplied by three-phase wye service.
Facility engineers at this site experienced repeated problems with the failure of electrical distribution equipment. A distribution transformer overheated and failed, circuit breakers were tripping, and electrical connectors were burning out. These problems are all symptomatic of overload conditions.
However, initial measurements of phase currents using a true RMS ammeter showed current readings of 257 to 298 amps. These values did not exceed equipment ratings.