See this:
https://forums.mikeholt.com/threads...st-not-meant-to-be-used-on-208-or-240.137807/
Would it turn on without letting out the smoke sealed at the factory? yes, at least for the time being. In the long-run and in a large quantity, best to check with factory engineers.
Official answer is likely a
no, unless you have a written approval from the factory.
The front-end of ballast is not always "symmetric" and EMI suppression and surge protector component may fail prematurely and internal fuse may only be on the line side where as a symmetric design would have protection on both input leads. It could also lead to RF interference issues.
If a ballast experiences an internal fault, such as a shorted capacitor, it would blow the input fuse, which is in series with the black lead.
If you run it across A and C (both leads at 240v in reference to case) with ground B phase and a fault develops between the case and the the white lead (unfused), it may trip the branch circuit.