C501 CREW HAD A RWY INCURSION AT SBP.

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ON TAXI; TWR'S CLRNC TO ME WAS TO 'TAXI TO RWY 29; HOLD SHORT RWY 25.' APCHING HOLD LINE TO RWY 25; 2 SEPARATE EVENTS OCCURRED: 1) TRUCK WITH YELLOW FLASHING LIGHTS ON TXWY PASSED MY L WING TRAVELING TOWARD TAIL OF ACFT. 2) AS I TURNED TO SEE TRUCK WITH FLASHING LIGHTS; I NOTICED 2 CIRCUIT BREAKERS POPPED WITH ASSOCIATED CAUTION LIGHTS. MY ATTN WAS DIRECTED TO CIRCUIT BREAKERS AND TELELITE PANEL AND 1 SECOND LATER I STOPPED THE ACFT. THE NOSE OF ACT WAS NOW ON HOLD LINE (ABOUT 2 FT OVER). I WAS ABOUT TO TELL COPLT TO RPT THIS TO GND CTL AND THEN HEARD TWR SEND A C172 AROUND ON BASE TO FINAL. HIS CALL WAS THAT A 'CITATION JET' HAD CROSSED THE HOLD LINE. AS SOON AS THE C172 ROLLED OUT ON FINAL; AT 600 FT AGL HE WENT AROUND WITHOUT INCIDENT. TWR TOLD US TO CONTINUE TO TAXI. UPON LNDG; I TRIED TO CONTACT TWR PERSONNEL TO EXPLAIN THE SLIGHT INCURSION OVER HOLD LINE BUT NO ONE RETURNED CALL. MY FAILURE TO STOP ACFT BEFORE HOLD LINE WAS CAUSED BY THE TRUCK DISTR PLUS THE POPPED CIRCUIT BREAKERS. I HAD EVERY INTENTION TO STOP.