Electricians Lock-Out Safety Tool.
Electricians Lock-Out/Safety Tool and Lock. Size – Lock-Out Tool 7 1/2″ x 3″. Pad Lock 5″ x 2″ inches.
All the electrical panels on-off switches had safety holes which enabled the electrician to clamp this tool through the panel front and switch and would place a padlock through the holes in the handle of the tool, that would stop anyone flipping the switch if the Electrician was working on the panels.