A CANADAIR CL65 WITH AN INOP MAIN SHIP'S BATTERY CHARGER IS DEFERRED BUT THE INCORRECT CIRCUIT BREAKERS ARE OPENED DISABLING THE APU BATTERY CHARGER NOW SUPPLYING THE STANDBY DC BUSS.

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AFTER HAVING OUR ACFT WORKED ON FOR 2 MECHANICAL PROBS; I WENT OVER THE MECH'S WORK. ONE ITEM WAS A LEAKING ESCAPE HATCH. THE HATCH WORK APPEARED TO BE COMPLETE AND THE SIGNOFF WAS IN ORDER. THE OTHER ITEM WAS A DEFERRAL OF THE MAIN BATTERY CHARGER. THIS DEFERRAL HAS 2 OPERATIONAL OPTIONS PERTAINING BECAUSE OF THE COMPLEXITY OF THE PROC TO OPERATE WITH THE APU OPERATIVE TO THE APU. THE APU CAN BE SECURED OPERATIVE OR INOP. ACR MAINT CTL INSTRUCTED THE CONTRACT MECH TO SECURE THE APU INOP. THIS PROC IS WITHOUT NEED OF ANY TOOLS OR TEST EQUIP AND IS ACCOMPLISHED IN THE COCKPIT. THIS PROC INVOLVES MAKING SURE; BY COCKPIT INDICATIONS; THAT THE APU IS OFF AND THE APU DOOR IS CLOSED. THE MECH THEN OPENS AND COLLARS CIRCUIT BREAKERS N12 AND E5 ON CIRCUIT BREAKER PANEL #1. UPON INSPECTION; I FOUND THAT UNDER ACR MAINT CTL'S DIRECTION; OUR CONTRACT MECH HAD OPENED AND COLLARED CIRCUIT BREAKER E5 ON CIRCUIT BREAKER PANEL #2 (APU BATTERY CHARGER) INSTEAD OF E5 ON CIRCUIT BREAKER PANEL #1 (MAIN BATTERY CHARGER). I BELIEVE THIS ERROR WAS A CONSEQUENCE OF SEVERAL FACTORS: 1) THE CONTRACT MECH'S INEXPERIENCE WITH THE CL65. 2) ACR MAINT CTL'S INEXPERIENCE -- A RESULT OF HIGH TURNOVER. 3) THE UNDERSTANDING OF ACR MAINT CTL DEPT.