Well, being that your location says NYC, you're a little behind the times haha. Take metro north up a ways and we are on the 2017 NEC. But, in 2014 NEC 422.5 Ground-Fault Circuit-Interrupter (GFCI) Protection. " The device providing GFCI protection required in this article shall be readily accessible."
422.51 Vending Machine - (A)"cord-and plug connected vending machines manufactured or remanufactures on or after January 1, 2005, shall include ground-fault circuit interrupter as an intergral part of the attachment plug or be located within 12in. of the attachment plug. Older vending machines manufactured or remannufactured prior to January 1, 2005, shall be connected to a GFCI protected outlet" (B) "Vending machines not utilixing a cord and plug connection shall be connected to a ground -fault circuit-interrupter protected circuit."
So don't go hiding the plug behind the machine unless you have a GFCI device elsewhere that is readily accessible.