So what year???

[cda]

So anyone about what year these type boxes started showing up???

 

[TheCommish]

Look for a data code/stamp on them. BTY the outer jacket for the left Romex is s bit short

 

[fatboy]

And the upper one is not fastened within 6"

 

[mark handler]

I do not know but did find this trivia
1930-39 Spelsberg company created the First plastic junction box, Bakelite.

And in the 1920s Polyvinyl chloride, PVC, was first used in electrical cable insulation.