I put in two outlets:
50A 4 wire in kitchen
30A 4 wire in laundry
in both cases I put a 4 inch square box and a 1 gang plaster/switch ring on the box.
The 50A outlet fit into the 1 gang ring
The 30A outlet did not fit into the 1 gang ring without widening the ring.
I'm often not clear, hope this explains it
Thanks,
