In switzerland we have a plug called "T 15". You can use it for just single phase or three phase. It is often used in workshops and places like this. I'm not sure, I think just the swiss plug system has such a dual use plug.
With T15 you can plug in a normal just L-N plug (like a normal USB charger), a L-N-PE plug (normal computer) or a 3L-N-PE plug.