As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON TAKEOFF ROLL, AFTER ENGINES WERE UP TO SPEED FOR TAKEOFF, ESSENTIAL AC BUSS WENT OFF LINE A , B, C PHASE C/B'S ON ESSENTIAL AC POPPED. REJECTED TAKEOFF AND RETURNED TO BLOCK. TROUBLESHOT ELECTRICAL SYSTEM AND FOUND NR 4 GENERATOR VOLTAGE REGULATOR HAD LOW VOLTAGE OUTPUT. REPLACED NR 4 GEN VOLT REG, SYSTEM OPS CHECKED GOOD PER MM CH 24.