Matthewm1965,
Nominal voltage is the designated voltage for an electrical system. Based on the nominal voltage , all the other parameters are defined. (It is like your name. Everything is based on your name) But if you measure the voltage on a system where the nominal voltage is 480 V or 4.16 kV you will not find that value. It may vary +/- (x) percent. Therefore, in ANSI world, that variation is defined in ANSI C84.1. Similarly, Based on above, in ANSI world, the motor "Rated Voltage (Name plate voltage)" is listed for various nominal voltages.
So you have to select the motor name plate voltage accordingly.
Therefore, 460V should be the name plate voltage for motors operating on a nominal system voltage 480V.
In ANSI world. ANSI C57.12.10 lists the standard nominal voltages of the high voltage side of transformers. Accordingly, a 4.16 kV-480 V transformer shall be connected to a network where primary nominal system voltage is 4.16 kV. Then 480V will be the voltage at transformer secondary terminals at full load.
But in IEC world this ratio is different. IEC 60076 doesnot list any secondary voltages.
Hope the above answers your question.