This question just raises more questions than can be answered without more information. And without more to go on there is no right or wrong. And you dont nessesarily have to have a grounded conductor to have 120...
This is some commentary from 250.20(D)
Two of the most common sources of separately derived systems in premises wiring are transformers and generators. An autotransformer or step-down transformer that is part of electrical equipment and that does not supply premises wiring is not the source of a separately derived system. See the definition of premises wiring in Article 100.
A read through 250.21 is appropriate too, as this control panel may fall under this code as well.
Now, a question: Is the Control Panel part of "Listed" equipment, or made in the field?
If made, why not use a different voltage.
