What was found
ELECTRICAL PLUG CODE E357 MALE P/N 206037-1, FEMALE, P/N 206036-3. WHILE IN CRUISE FLIGHT, SMOKE WITH AN 'ELECTRICAL SMELL' BEGAN COMING OUT OF OVERHEAD SWITCH PANEL. PILOT INITIATED A SHUTDOWN OF ELEC SYS. SMOKE LASTED ABOUT 10 SECONDS, 3 EXTERIOR LIGHTING CB'S (STROBES, NAV LIGHTS, AND RECOGNITION LIGHTS) WERE TRIPPED. PILOT GRADUALLY RESTORED POWER TO THE ELEC SYS AND SMOKE NEVER REAPPEARED. THE 3 TRIPPED CB'S WERE NOT RESET IN FLIGHT. INVEST BY MECH IN SIDNEY REVEALED WHEN ANY OF THE 3 BREAKERS WERE RESET E367 (AN OVERHEAD DISCONNECT PLUG) GOT HOT AND STARTED TO SMOKE. NO REPAIR COULD BE MADE IN SIDNEY. THE 3 EXT LIGHTING SYS WERE 'MEL'D' PER DUNCAN MEL AND TRIP WAS CONTINUED WITHOUT INCIDENT.