live wire
An electrical wire through which there is a flow of electrical current.
live wire: a conductor carrying active voltage
A live wire is any conductor that carries electrical potential at the moment you are working with it. Unlike a neutral or ground conductor, a live wire maintains voltage relative to earth, typically 120 volts in North American residential circuits or 230 volts in European systems. The moment current flows through it, or even when it sits idle but energized, it presents a shock hazard to anyone who contacts it while grounded.
In three-phase industrial systems, all three phase conductors are live wires, each carrying voltage offset by 120 degrees. A single-phase supply has one live wire paired with a neutral return path. The neutral wire itself is not live in normal operation, though it carries return current. This distinction matters: touching a neutral wire in isolation typically poses less hazard than touching a live wire, but any contact between a live wire and ground creates a complete circuit and a shock path through a person's body.
Recognition and Safety
Live wires are typically color-coded red, black, or brown in industrial and residential installations, though colors vary by country and standard. In old installations or field-rewired circuits, color coding cannot be trusted; testing with a non-contact voltage detector or multimeter is the only reliable way to confirm whether a wire is live before touching it. A wire can remain live even after a circuit breaker appears to have shut down a load, because upstream components or feedback from parallel circuits may maintain voltage.
The term itself comes from the observation that electricity makes things move and animate: a live wire is one with flowing current or potential, as distinct from dead wires that are safely de-energized. In informal usage, calling a person a live wire means they are energetic and quick, an analogy to the constant activity in an energized conductor.
Identifying live wires is the first step in any electrical work. De-energizing a circuit, verifying it is dead with test equipment, and only then working on it is standard lockout/tagout procedure. Respecting the distinction between live and dead conductors is fundamental to electrical safety in any trade.