Electric Current (Amperage)

Starters draw very high currents. Fuses limit current to protect wires. Current clamps measure it without disconnecting wires. A typical parked car draws only a small current once its control units have gone to sleep, while a starter motor may draw a very large current for a few seconds. Fuse ratings are matched to wire size to prevent overheating.

Voltage pushes current through the resistance of a circuit.

Excess current overheats wires. Measuring current incorrectly can blow multimeter fuses.