Where does the electricity go?

One of the joys of teaching classes and workshops is watching the expressions on people's faces when they suddenly get it. That happened the other day when one of the attendees in a class pulled me aside during a break.

"I've always wondered," he said. "where the electricity goes. I thought it came back through the neutral and went into the ground."

He was pointing to an illustration I had drawn of a typical circuit, and he indicated that he thought the current literally flowed into the earth where it just magically...disappeared maybe?

Of course, that's not what happens at all. The current flows in a loop starting from the supply, then through the circuit, and back to the supply again. There is just enough energy to return the current to the supply, and then it starts over again.

The reason we earth our electrical systems by driving a ground rod (or using one of many other ways to connect the electrical system to the earth) is mainly for lightning protection and for a 0-volt reference, which stabilizes our voltage. If lightning strikes the building or the electrical system, the connection to the earth funnels the energy into the earth so it can be dissipated. But that connection has nothing to do with the normal path for current flow.