Union workers overwhelmingly approved a new collective bargaining agreement with Consolidated Edison Wednesday.

After the largest lockout of workers in U.S. history, Local 1-2 of the Utility Workers Union of America voted in favor of accepting the four-year deal.

One of the most important provisions prevents Con Ed from changing pension plans of union members hired before July 2012 in future agreements.

The deal also stops the company from hiring outside contractors unless an independent adviser says it's necessary.

Con Ed employees went back to work on July 26, ending a nearly month-long lockout.