A recent spate of attacks on electrical substations in North Carolina and other states has underscored the continued vulnerability of the nation’s electrical grid, according to experts who warn that the power system has become a prime target for right-wing extremists. Over the last three months, at least nine substations have been attacked in North Carolina, Washington State and Oregon, cutting power to tens of thousands of people. After those attacks, federal regulators ordered a review of security standards for the electrical system. The Moore County attack caused 45,000 people to lose power, some for five days. Concerned about the sabotage, legislators in North Carolina, South Carolina and Arizona have introduced bills that would require 24-hour security at substations or toughen penalties for damaging them.