In a letter last month, four lawmakers asked the Federal Energy Regulatory Commission (FERC) and the North American Electric Reliability Corporation (NERC) to determine whether stronger federal standards are needed to ensure the security of our national electric grid after a sophisticated physical attack last year on a transmission substation in California caused millions of dollars in damages.

Sens. Dianne Feinstein, D-Calif., Ron Wyden, D-Ore., Harry Reid, D-Nev., Al Franken, D-Minn., and several other senators met last week with industry and government officials to understand the progress that has been made through voluntary measures to protect the bulk power system. The lawmakers were encouraged by the improvements made during the last year, but are requesting more information to determine whether the power grid could benefit from additional standards.

“We are concerned that voluntary measures may not be sufficient to constitute a reasonable response to the risk of physical attack on the electricity system,” the senators wrote in the letter. “While it appears that many utilities have a firm grasp on the problem, we simply do not know if there are substantial numbers of utilities or others that may have not taken adequate measures to protect against and minimize the harm from a physical attack.”

“A chain is only as strong as its weakest link,” they added.

An attack on Pacific Gas & Electric’s Metcalf transmission substation – which included severed transmission cables and nearly 100 rounds of gunshots – on April 16, 2013, nearly shut down the substation, which could have caused a large-scale blackout in California and surrounding states. The attack served as a “wake-up call” to the potential security risks to the power grid.

The senators requested responses from Acting FERC Commissioner Cheryl LaFleur and the president and CEO of NERC, Gerry Cauley.