As specified in the Code, where are you required to make the connection between the equipment grounding conductor and the grounded neutral conductor at a 208Y/120-volt, 3-phase, 4-wire service?

Most states require an electrician to pass an exam to receive a journeyman or master electrician license.  State exams cover these topics:  Electrical Theory, Trade Knowledge, Grounding and Bonding, Wiring Methods and Installation, Overcurrent Protection, Load Calculations, etc.