The North Carolina Utilities Commission will hold an additional hearing to determine if Duke Energy can merge with Progress Energy.
State regulators announced that climate-change nonprofit NC Warn will have a chance Monday to cross examine witnesses who want the merger.
The ruling came Tuesday after the nonprofit and energy giants filed dueling motions this week arguing if additional hearings were needed. NC Warn argued the merger could drive up rates for customers, and the energy companies responded that no further hearings were necessary.
The $13.7 billion merger would create the nation's largest electric utility, serving 7 million customers in six states.
The merger cleared a major hurdle June 8 when it was approved by federal regulators after more than a year of consideration.