Image taken about a century ago or a bit before.. Electric street lights in their very earliest days (after c.1880)operated on a street series circuit. Basically, they were wired (in electrical) series very much like modern-day Christmas lights. When one burned out a provision was made within the lamp socket so the rest of the lights would remain lit. This methodology remained as the utility and muncipality standard of street lighting operation until the 1950's (or so) when 120-volt street lights operated from an individual photoelectric lighting control affixed to the luminaire.