An active multi-module switching (MMS) system provides at least Tier-III level reliability to a data center using a UPS system with only N+1 redundancy. Only one additional UPS module is provided over the total number of UPS modules required to fully power the loads. The active MMS system includes a controller, a control circuit, and a number of distribution units each having electrically operated circuit breakers and sensor components. The active MMS system operates to control the switching components on each of the UPS modules as well as to selectively connect/disconnect individual UPS modules from MMS operation. This allows for disconnection of a UPS module from the critical load bus whenever maintenance on the UPS module is required.