To some employers, the Occupational Safety and Health Administration (OSHA) is best known for its surprise inspections, checking to see if an establishment is complying with the agency’s standards, and issuing fines when it fails to do so. But to the firms who build and maintain the U.S. power grid — the nation’s electrical transmission and distribution infrastructure — OSHA has become a partner in a collective enterprise that has prevented hundreds of serious injuries and saved dozens of lives.