Electrical Code…
Apparatus intended to be connected to nonincendive field wiring.
Informational Note: For further information, see ANSI/ISA-12.12.01-2013, Nonincendive Electrical Equipment for Use in Class I and II, Division 2, and Class III, Divisions 1 and 2 Hazardous (Classified) Locations.
(National Electrical Code® 100-1)