Inrush current

The surge a circuit draws at the instant of connection, before steady state — discharged capacitors look like shorts, cold filament/motor resistance is low, transformers can saturate. Often 10–100× the running current, gone in milliseconds.

In practice

USB is the textbook case: the spec allows ~10 µF of hard-attached capacitance because plug-in inrush from more can droop the host port and corrupt enumeration. Fixes are soft-start switches, NTC inrush limiters, or staging the capacitance behind a regulator.

See it for real