Federal energy regulators said an industry proposal to bulk up the nation's electric grid security was inadequate and needed fixing.
The Federal Energy Regulatory Commission told the industry group North American Electric Reliability Corp. (NERC) to correct weaknesses in its security plan, The Wall Street Journal reports.
The plan was drafted by the industry group in response to a physical attack on a California substation last year.
NERC proposed that companies should develop their own security plans for substations, that could create cascading blackouts if hit with an attack. That would cover only a few hundred of the nation's 55,000 transmission substations.
Acting Chairwoman Cheryl LaFleur said the actions were "an important step forward in protecting a critical element of our bulk electric system."