I used to come across this alot on an old residential high rise. The building managment wanted to install receptacles for all the hardwired ranges as the units became empty. Origional installation was harwired with a 40amp breaker and 10awg wire.
Inspector let us install 5-50R range receptacles but we had to use 30amp breakers.
Normally we would have to re-wire to 8awg but these places had real small kitchens so only a small apt-size range would fit.
