The Tennessee Valley Authority continues to repair tornado damage to its power transmission lines from Friday's storms, spokeswoman Myra Ireland said.
The most damage is in Harrison and Davis Mill areas in Hamilton County and into Bradley County, Ireland said.
A line near Murphy, N.C., and two lines west of Huntsville, Ala., were damaged as well, she said.
On Sunday evening, nine lines still were out of service, down from 16, Ireland said.
"A total of 20 structures are damaged - from minor damage to tangled [steel and cables] on the ground," she said.
TVA officials on Saturday estimated it will be nine to 10 days for the worst damage to be repaired and all of the transmission system returned to normal operation.
Seven distributors on Sunday still had about 4,900 customers without power in North Alabama and Middle, East and Southeast Tennessee, TVA said.
Ireland said there is no cost estimate yet for the storm damage and repairs.
Part of that cost will be lost generation from Sequoyah Nuclear Plant. Because of damaged lines, one reactor was running at only 80 percent of power Sunday.
Sequoyah's other reactor was shut down Feb. 27 for refueling and will come back on line later this month.
The April 27, 2011, tornadoes cost TVA ratepayers $39 million for structural repairs and $95 million in replacement power.