AN MD80 WAS DISPATCHED FROM A NON MAINT STATION WHERE THE L LAVATORY WAS DEFERRED PER THE MEL PROCS. A CIRCUIT BREAKER WAS OPENED AND LOCKED PER THE MAINT CTLR.

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IN ZZZ; WE WROTE UP A FLT ATTENDANT RPT OF A NOISE IN THE L-HAND AFT LAVATORY OF ACFT X. WE HAD LCL MAINT COME OUT AND WORK WITH ZZZ1 MAINT CTL VIA THE CELL PHONE TO REMEDY THE PROB. IT WAS DETERMINED THAT THE LAVATORY SHOULD BE REMOVED FROM SVC USING MEL 38-2B. L-HAND LAVATORY INOP; BLOCKED. AFTER THIS WAS DONE; THE LCL MECH PRESENTED US WITH THE LOGBOOK AND WE PULLED OUT OUR COPY OF THE MEL BOOK AND VERIFIED THAT ALL OF THE CONDITIONS AS PERTAINED TO THE MEL WERE ACCOMPLISHED (LAVATORY DRAINED AND LOCKED; PLACARDS PUT ON INSIDE DOOR AS WELL AS ON THE SVC PANEL). WE RECEIVED AN AMENDED RELEASE AND PROCEEDED TO PREPARE FOR DEP. THE LCL MECH THEN RETURNED AND PULLED AND COLLARED A L-HAND LAVATORY CIRCUIT BREAKER WHICH CTLS THE LIGHTING. HE WAS DIRECTED TO DO THIS BY MAINT CTL. WE DEPARTED WITHOUT FURTHER ADO. ON ARR IN ZZZ1; THE ZZZ1 BASED MAINT TEAM DECIDED THAT THE PULLED AND COLLARED BREAKER WAS NOT PART OF THE MEL AND THAT WE HAD ACTUALLY REQUIRED AN ENGINEERING ORDER IN ORDER TO HAVE BEEN LEGAL. WE FELT THAT WE DID A CONSCIENTIOUS JOB OF ENSURING THAT THE PAPERWORK WAS IN COMPLIANCE AND GOT CAUGHT OFF GUARD BY THE CIRCUIT BREAKER SIT.