An MD80 Captain rejected the takeoff after the AC CROSSTIE LOCKOUT light illuminated. Maintenance determined that both Generator Control Units were loose in the E and E racks.

Narrative

On previous flight the crew had reported that shortly after takeoff the lights flickered and the electrical power shifted several times resulting in the 'AC Crosstie Lockout' light illuminating on the overhead annunciator panel. Arriving at the aircraft the next morning; we saw that the write-up had been fixed. Pushback was normal until we started the right engine and the 'AC Crosstie Lockout' light illuminated again. We accomplished the QRH procedure for the problem and since there were no other abnormalities; I decided to flight crew placard the problem; however we returned to the gate because we needed to run the APU for the entire flight and we needed more fuel. After refueling; we proceeded to the runway and started takeoff. Everything was normal until we hit a bump and suddenly the aircraft started searching for electrical power. Chimes started ringing; lights flashing; the annunciator panel lights were flickering very fast and the takeoff/warning started warning us; 'FLAPS/SLATS'. I looked at the airspeed and it was only slightly faster than 80 KTS. I aborted. We taxied to the gate; contacted the Dispatcher and Maintenance Technician and they determined (after troubleshooting the electrical system) that we needed a new cross tie relay. The nearest one was several hours away. When the mechanics from that airport came out they went into the E/E (Electrical/Electronic) compartment and found both Generator Control Units (GCU) were loose in their tracks to the point of 'almost falling off the rack.' They re-secured the GCU's to their connections; taxied the airplane around and released the aircraft to us. We ferried uneventfully. I don't know when the aircraft last had maintenance done on the generators (GCU's to be specific); but it is very odd that they both came loose at the same time.