CARMEL, Ind. -- Power companies are seeing record demand as Hoosiers and others across the U.S. try to stay cool during the heat wave.

As power grids near their limits, a group of experts in Indianapolis manages one of the world's largest energy markets, 6News' Julie Pursley reported.

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Group Balances 15 States' Power From Indiana

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Midwest Independent System Operator, or Midwest ISO, balances supply and demand from a facility in Carmel. Midwest ISO monitors power usage at hundreds of power companies in 15 states and parts of Canada.

Midwest ISO said the region experienced record demand on Monday, prompting the organization to encourage power companies to release statements urging consumers to go easy on energy usage, particularly during the heat of the afternoon.

Security at the facility is very tight. 6News' cameras were not allowed on the floor on Wednesday.

"We're balancing and monitoring and making sure the power goes where it needs to meet the load," said Todd Hillman, ISO's executive director.

The organization said the region has plenty of resources to ensure that power stays on during a heat wave that is holding much of the country in its grip.

Wednesday was the third-straight day that the group asked consumers to cut back on electricity consumption.

"We saw that we were going to be pretty tight in terms of supply and load. So, in those instances, we have established procedures that we follow," Hillman said. "Part of those procedures is to enable the market to issue conservation efforts."

Indianapolis Power and Light and Duke Energy again asked customers to cut down on electricity usage between 1 p.m. and 8 p.m. on Wednesday.