Please explain the logic why after 9/11 there was a rush to replace chainlink fencing with brick walls around the little substations so no one could see in.
I don’t know why the utilities in your area decided to do that. I can tell you that of the hundreds of substations my company is in charge of, I know of none that have a brick fence surrounding it. I do know that some places put up walls and such around substations because people don’t like looking at them, but that is about cosmetics, not security.