C210 MAINTAINING 9000 FT HAD A SHOWER OF SPARKS IN FOOT TUNNEL IN THE COCKPIT. GIVEN VECTOR TO THE NEAREST ARPT AND LANDED. FOUND PITOT HEAT CIRCUIT BREAKER HAD TRIPPED DUE TO ALT ENCODER BECOMING LOOSE AND CONTACTING ELECTRICAL TERMINALS. SECURED THE ENCODER AND INSURED NO FURTHER CONTACT WITH ELECTRICAL TERMINALS. CONTINUED THE FLT NORMALLY.

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AT APPROX XA00Z; WHILE ON AN IFR FLT PLAN FROM AHN TO SFB; A SHOWER OF SPARKS OCCURRED IN THE FOOT TUNNEL ON THE PLT'S SIDE. MACON TRACON WAS ADVISED THAT I NEEDED THE NEAREST ARPT 'RIGHT NOW.' THE CTLR ASKED IF THIS WAS AN EMER AND I REPLIED 'WITH SPARKS IN THE COCKPIT I SUPPOSE IT IS.' CLRNC AND RADAR VECTORS WERE GIVEN TO OKZ AND A NORMAL APCH AND LNDG WAS MADE. AFTER SHUTDOWN; I INVESTIGATED THE PROB AND DETERMINED THAT THE PITOT HEAT CIRCUIT BREAKER HAD TRIPPED DUE TO THE ALT ENCODER COMING IN CONTACT WITH THE PITOT HEAT ELECTRICAL TERMINALS. THE ENCODER HAD BECOME LOOSE DUE TO VIBRATION. THE ENCODER WAS SECURED IN PLACE AND ISOLATED FROM CONTACT WITH ANY ELECTRICAL CONTACTS OR TERMINALS. THE PITOT HEAT CIRCUIT BREAKER WAS LEFT IN THE TRIPPED POS. A FULL PWR STATIC RUNUP WAS PERFORMED AND NO FURTHER SPARKING OCCURRED. THE FLT WAS CONTINUED VFR TO THE MAYPORT; FL; AREA WHERE AN IFR CLRNC WAS REQUESTED AND GRANTED BY JAX TRACON; DEST SFB. NO FURTHER ANOMALIES WERE NOTED AND THE FLT TERMINATED SAFELY AT SFB (VISUAL APCH RWY 18).