How does electricity get to your home

Using a higher voltage in transmission lines is more efficient because it reduces the losses along the way.
But it is also much more dangerous. Hence overhead transmission lines are so tall.
Substations are used to step up or step down the voltage as necessary
Mini substations are used to monitor and control the power on the grid.
All substations are built with a grid of grounding rods and conductors buried below the surface.
In the event of a fault, the substation needs to be able to sink lots of current into the ground to trip the breakers as quickly as possible.

[djhatton]

Wouldn’t you say the ground grid in a substation is for step potential concerns and return path for fault current to transformer. Earth as in dirt is a parallel path to any overhead neutral wires. And the earth is a poor conductor compared to the wire. Current isn’t somehow sinking into the ground. It’s returning to transformer to complete the electrical circuit. Update your slides