ELECTRICAL SMOKE FROM BEHIND THE INST PANEL OF A PIPER PA38-112 IS WELL TAKEN CARE OF BY THE OPERATING HANDBOOK PROCS.

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NIGHT LCL FLT WITH STUDENT PLT. FLEW OUT TO PRACTICE AREA FOR MANEUVERS. COMPLETED MANEUVERS THEN BEGAN TO SMELL POSSIBLE BURNING INSULATION. INTERIOR PANEL LIGHTS FLICKERED AND FAILED. ALL GAUGES READ NORMAL INCLUDING AMMETER AND ALTERNATOR ANNUNCIATOR NOT ILLUMINATED; NO CIRCUIT BREAKERS POPPED. WE PROCEEDED BACK TO FCM. SMELL BEGAN TO INTENSIFY AND I TURNED OFF ALL ELECTRICAL NON ESSENTIAL EQUIP. WE THEN WENT THROUGH THE EMER ELECTRICAL FIRE INFLT CHKLIST; SHUT OFF BATTERY MASTER/ALTERNATOR AND ALL ELECTRICAL EQUIP. SHORTLY AFTER THE SMOKE STOPPED; WE LANDED WITHOUT INCIDENT AND TAXIED BACK TO RAMP. THERE WAS HEAT COMING FROM UNDER THE INST PANEL. NO FIRE WAS EVER SEEN OR PRESUMED PRESENT. POSSIBLE CAUSES COULD HAVE BEEN AN OVERHEATED BATTERY OR 2 WIRES TOUCHING THAT MELTED SOME WIRE INSULATION. THROUGHOUT ENTIRE FLT; ALL GAUGES READ NORMAL AND THE ONLY ELECTRICAL EQUIP LOST WAS THE PANEL LIGHTS. NO HUMAN FACTORS CONSIDERATIONS. WE PERFORMED EVERYTHING AS PER THE CHKLIST AND ALL WENT WELL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: AFTER THE FACT; MAINT FOUND A SHORT IN THE NAV LIGHT WIRING BEHIND THE INST PANEL.