The ongoing AI boom has made energy stocks one of the hottest corners of investing. Once-boring utility companies are soaring as tech giants look to feed their ravenous data centers , while three of the top 10 best performing stocks in the S&P 500 this year are wholesale power providers with nuclear businesses. Meanwhile, all this demand for energy is lifting another set of companies: firms that help build and maintain North America's electrical grids , including our three picks listed further below.

Consult any energy sector report , and you'll discover that the country's grid infrastructure requires a major facelift . This means portfolio managers are keeping a close eye on manufacturers that build essential equipment like transformers and switch gears —or provide services like cooling solutions for the sever racks in data centers.

“The industrial companies are in the sweet spot,” Stephanie Link, who oversees a $5.4 billion portfolio as chief investment strategist at Hightower Advisors, recently said in an interview with Fortune .

Investors have already piled into the grid-building space, with many top picks trading at the types of lofty premiums that have led to a multitude of warnings about an overly frothy AI trade. For investors playing the long game, however, it could still pay to hop on the bandwagon.

Link was struck by a comment from the CEO of Quanta Services , a Fortune 200 company projected to earn $23.7 billion in revenue for 2024, per Visible Alpha. Duke Austin, who leads the electrical and pipeline contractor, told analysts after Q1 that the energy needs of data centers in the company’s network was “mind-blowing.”

“I don't think I've heard a CEO say anything like that before in my lifetime,” said Link, who is also a regular CNBC contributor. “These are conservative industrial manufacturing, old-school companies that are seeing a lot of business and a lot of upside.”

America’s energy needs skyrocket as its grid ages

The boom has a lot to do with timing. Much of America’s grid infrastructure was built in the 1960s and 1970s, and 70% of its transmission lines are over 25 years old and approaching the end of their typical 50-to-80-year lifespan, according to the U.S. Department of Energy.

That’s happening just as the country’s electricity demand is skyrocketing for several reasons. That includes data center demand, which could jump an estimated 160% by 2030, per Goldman Sachs .

But there’s plenty of other factors at play too, including the wave of “ reshoring ” among American manufacturers. Rising global temperatures, meanwhile, intensify the need for air conditioning. On the other hand, the clean energy boom—and the growing adoption of green products like electric vehicles and heat pumps—all put more strain on the system.