Definition
A small, unintended flow of electrical current that escapes through insulation, across a contaminated surface, or between conductors that are supposed to be electrically isolated from one another. Leakage current is normally very small, but it increases when insulation deteriorates, moisture is present, or contamination builds up on electrical components.
Plain English
A tiny bit of electricity that sneaks through somewhere it isn't supposed to go, like across a dirty or damaged insulator instead of staying inside the wire.
Context Anchor
Seen in aircraft electrical system troubleshooting, especially when checking wiring, insulation, batteries, alternators, capacitors, and other electrical components.
Derivation
From 'leak,' meaning to escape slowly through a small opening. The term pictures electricity behaving like water seeping through a barrier that should hold it back.
Why Pilots Care
Excessive leakage current signals insulation breakdown that can lead to overheating, fires, or loss of critical electrical systems.
Intuition Check
Do not picture oil or fuel leaking. In this term, leakage means unwanted electrical flow through a path that should mostly stop it.
Example Sentence 1
The technician measured leakage current across the capacitor to confirm the insulation was still within limits.
Example Sentence 2
High leakage current readings on the wing wiring prompted replacement of the harness.