Question about NEC

[Rollie Meyers]

I doubt anyone here unless they are a PoCo lineman is qualified to work on high voltage. I prefer line voltage/ low voltage over high/low voltage because even 12,470 volts is considered medium voltage. The low voltage wiring would need to be insulated for the highest line voltage in the enclosure, if the OP is bound & determined to use 24 volts as a control voltage I would recommend 24 VAC over VDC, due to lower costs & availability, since it is widely used in HVAC equipment, if a definite purpose contactor is used it needs to be UL listed not the backwards UR (UL recognized) marking, because UL recognized means it's a recognized component of UL listed equipment, so unless someone has a lot of spare cash to get their controls listed by a recognized testing lab such as UL, ETL or other, it's not kosher to use UR labeled components.

[Anthony Whitesell]

24VDC is a industrial standard, just a different industry. 24VDC components for control systems are nearly as plentiful as the HVAC. Just a matter of shopping in a different store.