"TEPCO has connected the external transmission line with the receiving point of the plant and confirmed that electricity can be supplied," the plant's operator Tokyo Electric Power Co said in a statement.
Another 1,480 meters (5,000 feet) of cable are being laid inside the complex before engineers try to crank up the coolers at reactor No.2, followed by numbers 1, 3 and 4 this weekend, company officials said.
If that works it will be a turning point.
"If they are successful in getting the cooling infrastructure up and running, that will be a significant step forward in establishing stability," said Eric Moore, a nuclear power expert at U.S.-based FocalPoint Consulting Group.