The $70 million project will create more than 200 jobs in the company's Transformer Solutions division.
"This really is truly a point where government and business came together to put together a state of the art facility that is creating jobs," said Thom Farrell, Transformer Solutions president.
SPX added 54,000 square feet to its existing building, bringing the space to 432,000 square feet. It's also the tallest building in Waukesha at 122 feet.
The vertical space is needed to build and test larger transformers, about three times the size of SPX's current products.
SPX's main customers are power companies across the country like WE Energies, Farrell said. These customers were asking for larger transformers to meet increasing demand.
"When you look at the aging infrastructure and you look at where the U.S. is going to be going over the next 40 years, you can see that a lot of replacement units are going to be needed just to maintain the reliability of the grid," he said.
Construction started in November 2010 on the facility, which has a 500-ton crane and hover pallets that are used to move the transformers through production.
About 150 of the new positions have been filled, and another 50 jobs will be created, Farrell said.
SPX has already received orders through the first year of production and is now taking orders for its second year.