Can anyone explain to me what is ment by nominal voltage? If you have a 120/240 service, is your nominal voltage the 120 legs to ground? or the 240? I do not understand how you can get 240 to ground. From what Ive read, the circuit is based on the equipment to be used. In other words, if you have 240volt heaters the circuit is considered 240v nominal yet what would be your reference point. You see nominal voltage all over the code book, I must have a thick head. Thanks
Nominal is the system voltage at the distribution point, say 120VAC.
Nominal utilization voltage is the volateg at the user point, that is on the nameplate of the equipment, say 115VAC.
Voltage ranges are the defined highs and lows around the above numbers thata re expoected to be maintained, so the systems and supplies are to be designed to comply with those limitations.
Range A:
Max. Utilization and Service: 126VAC
Min. Service: 114VAC
Min. Utilzation: 110VAC
Range B:
Max. Utilization and Service: 127VAC
Min. Service: 110VAC
Min. Utilzation: 106VAC
So the ranges define the acceptable limits around the nominal.