According to NFPA and ANSI the nominal system voltages (line to line) in the US are:
There are additional descriptions such as three or single phase, delta or wye, grounded or ungrounded, but in all cases these are the line to line voltages.
Utility voltages systems like 110, 115, 220, 230, 440 have been obsolete since 1949. There are some industrial plants that will use non-standard systems but these are usually very rare.
The confusion usually comes from utilization equipment, where manufacturers are allowed to rate devices at any voltage they want.
Fuse manufactures use maximum voltages of 125V, 250V, and 600V, and home appliances are usually at 125V.
Industrial motors are always rated at 115V, 200V, 230V, 460V, and 575V. But their instructions then list the nominal system voltage the equipment was designed to be used on (i.e. 230/460V motor on a 240V/480V system)
[This message has been edited by JBD (edited 01-09-2002).]