Is this inside of a Sub Panel, or is that Zinsco 20/20 inside of something else [maybe a "Spiderbox"], used to protect that 20 amp Receptacle???
Either way, one can only ponder "Whadda Heck Was That Joker Thinking!?!?!"
Imagine someone sticking their finger in there to throw the Breakers' Handle[s]!
That was sure nice of the Installer to leave "Access" on the side of the Receptacle with the Ungrounded Conductors' Terminations!
[pending the Receptacle is wired correctly
Need to include a little bit of risk with all installations Keep those Popsicle Sticks, Maynard - We will need them to turn on/off the breakers