Where are fault currents typically higher?

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When a fault happens, the amount of current is set by the impedance between the fault point and the power source. A short circuit drives current up because the path is almost a direct connection, so the fault current is roughly the source voltage divided by the impedance along that path. The closer you are to the source, the smaller that impedance tends to be, so the fault current is larger. As you move farther away along a line or feeder, impedance adds up and the fault current decreases. That’s why fault currents are typically higher near substations or generation sources and lower further down the circuit. Protective devices at the source must be prepared to interrupt these high currents, while downstream equipment experiences lower fault currents.