heater wires

[thekman]

I have a 480vac 300W flex heater, roughly 8" x 10" affixed to the back of an electrical cabinet, which is mounted inside a larger metal cabinet. The 2 20 AWG wires from the heater are running around the outside of the electrical cabinet through a bulkhead into the electrical cabinet.
I don't see any mention of flex heater wiring in the NEC that requires them to be covered by conduit or raceway. They are not interfered with by any moving parts nor human interaction. The only thing that might get on them is some biodegradable oil.
Section 426 talks about heaters, but I didn't really see anything pertaining to my situation.

 

[thekman]

the heater is actually mounted to a metal oil containment tank, mounted very near the electrical cabinet, and is UL recognized and CE compliant (the heater)