Progress in power system engineering for commercial buildings

The Edison Electric Institute ¿ National Electrical Manufacturers Association standard nominal system voltage designation of the higher voltage system referred to in this paper is 480 wye/277 volts. The maximum system voltage is 480 wye/277 and the average utilization voltage will be more nearly 460 wye/265 volts. To be consistent with the lower class designation, such as 208 wye/120 volts which is an average utilization voltage, some utilities have selected 460 wye/265 volts as a nominal system voltage designation. Whether the higher voltage system is called 480 wye/277 or 460 wye/265 volts, it is precisely the same system and has the same voltage spread.