When would inrush current typically be highest?

Inrush current is typically highest when devices are powered on. This phenomenon occurs because, at the moment of startup, electrical equipment like motors, transformers, or other inductive loads requires a large amount of current to establish electromagnetic fields and overcome inertia. The initial surge of current can be several times greater than the normal operating current, leading to a spike that is known as inrush current.

During steady-state operation, the current remains relatively stable and at a level that corresponds to the device's rated load. Likewise, when devices are powered off, there is no current flow, and extreme load conditions may cause an increase in current but generally will not equate to the high starting current experienced during the powering on process. Understanding inrush current is crucial for the design and proper sizing of electrical systems to prevent circuit breakers from tripping and to ensure reliable operation of devices.