San Diego wildfires and utility transmission line lawsuits

Aluminum transmission line thermal expansion → ground contact → wildfire. Utility settled for $300–400M; cost passed through to consumers via rate base.

So copper has unique electrical and thermal conductivity, and even though it's much more expensive than aluminum and steel we use it. Now, aluminum has sixty percent of the conductivity of copper, and so all those big 345 kilovolt transmission towers — that's aluminum, because you don't want to pay that much for the copper. However, the aluminum tends to get soft. So you actually make a composite. Those are steel cores with aluminum on the outside, and the steel gives you the strength. One of the reasons they're so tall is that when everybody's running their air conditioners during the summer, the wires heat up, and they actually have to make them tall enough so that as they heat up and expand, they don't touch the ground. Because if they touch the ground, they will start a forest fire or a brush fire. Plus it's not very good for the circuit breakers back at the power station. You'd lose your power. Seven or eight years ago they had some tremendous wildfires in San Diego that burned down all that part of southern California.