Definition
The brief, high surge of electrical current that flows into a device the moment it is switched on, before the current settles to its normal steady-state value. Inrush current is typical of motors, transformers, and incandescent lamps, where the cold resistance or unmagnetized state of the device allows much more current to flow during the first instant of operation than during normal running.
Plain English
When you first turn an electrical device on, it pulls a quick, large gulp of current for a fraction of a second. That gulp is the inrush current. After that brief moment, the device settles down to drawing its normal, smaller amount of current.
Context Anchor
Seen in aircraft electrical system discussions, especially when describing motors, lights, power supplies, and protective switches that may react to a starting surge.
Derivation
From 'inrush' -- a sudden flowing in -- combined with 'current,' the flow of electricity. The word picture is accurate: electricity rushing in the moment the switch closes, then easing off.
Why Pilots Care
Large inrush currents can overload batteries or trip circuit breakers, so aircraft electrical designs include protections and component ratings that account for the surge.
Analogy
It is like the extra push needed to get a heavy cart moving. Once the cart is rolling, it takes less effort to keep it moving.
Intuition Check
“Current” here does not mean present time or moving water. It means the flow of electricity in a wire or device.
Example Sentence 1
The landing light circuit breaker is sized to tolerate the inrush current that occurs each time the lamp is switched on.
Example Sentence 2
Circuit breakers on the main bus are sized to handle the inrush current from multiple avionics units powering on at once.