Hmmm, I don't know exactly, but according to both Mr. Castanet and my good friend maestro Udi Carmi (The Israeli olympic fencing team coach and a fencing historian by himself), production of the old fashioned epee blade seized by 1940. The electric epee was indeed introduced in the 1936 Berlin Olympics but gained some use only about two decades later, and was reserved for official competitions only for long time.
The post 1940 epee blade has a deep v-shaped fuller, even in a "dry" blade (= non electric). Electric blade has additional deep narrow cuts at the ends of the fuller, to accomodate the conducting wire.
I will try to look up for examples.
By the way, check this fabulous foil here: http://cgi.ebay.com/NICE-FRENCH-19t...%7C 240%3A1318