AN MD11'S EXTERIOR LIGHT CONTROL PANEL SHOWERED SPARKS WHEN THE WING AND TURNOFF LIGHT SWITCHES WERE TURNED OFF. AN EMER WAS DECLARED WITH A RETURN TO LAND.

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AFTER PASSING 10000 FT; I WENT TO TURN OFF THE LNDG AND NOSE LIGHTS; AS PER THE AOM. I ALSO PUT MY FINGERS ON THE WING AND TURNOFF LIGHTS BUT REMEMBERED THAT THEY ARE TURNED OFF AT FL180. I DID NOT PRESS THE SWITCHES BUT AS SOON AS I TOUCHED THE SWITCHES A SHOWER OF SPARKS AND A LITTLE BIT OF SMOKE WAS SEEN. THE SMOKE DISSIPATED FAST. THE FO WAS FLYING AND CONTINUED TO FLY. I CALLED MAINT CTL AND DISPATCH WHILE I WAS ASSESSING THE SITUATION AND GETTING MY THOUGHTS COLLECTED AND DISCUSSING THE SITUATION WITH THE CREW. AT THIS POINT I HAD THE RELIEF PLT LOOK AROUND THE FLT DECK TO CHK AND SEE IF ANY MORE DAMAGE WAS VISIBLE AND CHK STATUS OF THE CIRCUIT BREAKERS IN ORDER TO ASCERTAIN IF THERE WERE ANY OTHER SYS AFFECTED FOR A RETURN. WHEN I TALKED TO MAINT CTL/FLT CTL; I ADVISED THEM OF THE SITUATION AND ADVISED THEM THAT I WOULD BE MAKING AN EMER RETURN TO ZZZZ. I COMMUNICATED TO CTL THAT I WAS DECLARING AN EMER AND RETURNING TO ZZZZ AND TO HAVE THE FIRE TRUCKS AND EQUIP READY. I PASSED ON ALL THE PERTINENT INFO TO THEM AND INCLUDED NO HAZMAT INFO. AT THIS TIME THE SITUATION WAS STABLE; NO MORE SPARKS AND SMOKE VISIBLE. WE DUMPED AND RAN THE CHKLIST. I HAD THE RELIEF PLT BRIEF THE APCH TO US. WHEN WE WERE ALL READY AND CHKLIST COMPLETED AND RETURN INFO WAS IN THE FMC; I TOOK OVER THE FLYING POS FROM THE FO; A POSITIVE XFER OF CTLS OCCURRED. WE MADE A STABLE APCH AND DID NOT EXCEED ANY LIMITATIONS. AFTER LNDG; I TURNED OFF THE RWY AND WERE MET BY THE FIRE BRIGADE AND ESCORTED IN. AFTER BLOCK-IN; THE ACFT WAS SECURED BY ALL AND I PROCEEDED TO MAKE ALL THE PERTINENT LOGBOOK ENTRIES.