Definition
An electrical short circuit that has essentially zero resistance, allowing the maximum possible current to flow directly from the power source back to ground, bypassing the intended load. Because resistance is effectively nil, current is limited only by the source and the conductors themselves, which causes rapid heating, blown fuses, tripped circuit breakers, and a high risk of fire or component damage.
Plain English
A direct, full-strength short between a power wire and ground with nothing in between to slow the current down. The wire heats up fast and either pops the breaker or burns.
Context Anchor
Seen in aircraft electrical system troubleshooting, especially when a fuse blows, a circuit breaker trips, or a wire is damaged.
Derivation
"Dead" here means complete or absolute, as in "dead center" or "dead stop" — no qualification, no resistance left in the circuit. Combined with "short," short for "short circuit," it describes a fault that takes the most direct possible path with nothing restricting it.
Why Pilots Care
A dead short can cause rapid battery drain, electrical fires, or sudden loss of critical systems.
Analogy
It is like water suddenly getting a wide-open shortcut around the normal plumbing. The flow rushes through the wrong path instead of going where it was meant to go.
Intuition Check
Do not read “dead short” as a short amount of time or a dead battery. Here, it means a direct electrical fault with very little resistance.
Example Sentence 1
When the landing light circuit breaker tripped instantly on every reset, the mechanic suspected a dead short in the wing wiring.
Example Sentence 2
A dead short in the alternator output wire can overheat the wiring harness in seconds.