ELECTRICITY IS INVISIBLE STUFF, and yet it makes quite a mark on the modern landscape. The power plants that generate it, the transmission lines that carry it across the countryside, and the substations that dispatch it are all giant structures, hard to hide from view. The smaller-scale wires, utility poles, transformers, and other hardware that distribute electricity to homes and businesses are less impressive individually, but they are seen everywhere on city streets and rural roadways. In built-up areas, it’s hard to make a landscape photograph that doesn’t take in a power line. The whole country hums with the 60-cycle-per-second note of the electric power grid.

Generating plants are described in the preceding chapter. This chapter covers everything else electrical: power lines, substations, and the local-distribution network.

Some Electrifying Concepts

The network that brings power to a nation is not fundamentally different from the electrical system in your home. Wires carry electricity from city to city, just as they distribute it to lamps and outlets. The national network has switches, circuit breakers, and fuses that work much the same as those in your basement fuse box. They’re just bigger.

The basic unit of all electrical technology is the circuit. Current flows out from a source (such as a generator), along a conductor to a load (such as a motor or a light bulb), and then along another conductor back to the source. Without the complete round-trip path, nothing happens; breaking the circuit open at any point stops the current. (The opposite of an open circuit is a short circuit, when the outbound and inbound conductors touch, bypassing the load: Pffft!)