The 50 A. 250 V. config. is the only thing correct about that abortion, NM used in place of a proper flex cord, botched color code, and the worst is the use of a surface mounted receptacle for a cord connector,when they are dropped (not if, when) they shatter leaving exposed live parts for the user to contend with.
Note: Arrow Hart makes a connector ( AH6709N) that would be more OSHA "friendly" then a 4 square box / raised cover / receptacle combo.
