3 Phase line to line voltage application
Technically, it does work. Basically this produces the same load as a broken 3-phase motor might. The RCD should be able to deal with this, too. 

I dislike the solution, because this is unexpected for service personnel: "Two brown cables? huh?". Someone is bound to end up attaching a 120V-only device to those two leads at one point. 

Using a transformer dedicated to the devices to step up one phase to the required voltage would be way clearer.