Power has been restored to all but one company in the Brooklyn area of Jacksonville, according to JEA.
Service was restored to EverBank and Fidelity at about 2:40 p.m.
LPS was expected to have power back later Thursday afternoon.
"We thought we had one of the circuits back in for these folks who've been so patient with us. Unfortunately, it held for a short period of time and it kicked off again," JEA spokeswoman Gerri Boyce said earlier Thursday.
JEA went back in to figure out why the circuit was not holding, Boyce said.
"That probably will push everything back because we have to bring things back methodically," Boyce said.
A fire from an underground transformer at 221 Riverside Ave. Wednesday morning left about 100 customers without power and affected downtown traffic lights.
JEA said it had to cut off six circuit lines after the fire started at about 9:40 a.m., which affected large customers including the Florida Times-Union, CSX, Raymond James, FIS, Haskell, Prime Osborn Convention Center, Cummer Museum of Art and Gardens, Red Cross, YMCA, Five Points, the Federal Reserve Bank and the Federal Building.
Meanwhile, smaller businesses lost money by the minute.
"I don't know whose fault it is, but I need to be compensated. That's the bottom line," said John Varamogiana, who owns John's Deli in Riverside.
He said he likely lost hundreds of dollars Wednesday, and on top of that may have to throw his food away. He put his deli meats and salads on ice while the power was off, but that won't keep it fresh for long.
"Who's going to take care of this problem? Because it is a problem," Varamogiana said.
JEA said even though businesses lost money, it can't be held responsible, and it's spelled out in their service agreement.
"Anyone is welcome to file a claim, but service cannot be guaranteed 24 hours a day, seven days a week because things like this happen," Boyce said.