Distribution substations are located near to the end-users. Distribution substation transformers change the transmission or subtransmission voltage to lower levels for use by end-users. Typical distribution voltages vary from 34,500Y/19,920 volts to 4,160Y/2400 volts.
34,500Y/19,920 volts is interpreted as a three-phase circuit with a grounded neutral source. This would have three high-voltage conductors or wires and one grounded neutral conductor, a total of four wires. The voltage between the three phase conductors or wires would be 34,500 volts and the voltage between one phase conductor and the neutral ground would be 19,920 volts.
From here the power is distributed to industrial, commercial, and residential customers.