What is Blue Wire?
Blue wire is an electrical conductor identified by its blue insulation, commonly used in both residential and commercial electrical systems. In single-phase residential wiring, blue wires often serve as traveler wires in three-way and four-way switch systems, allowing for control of a light from multiple locations. In three-phase systems, especially in commercial or industrial settings, blue wires are designated as one of the phase conductors—typically the second or third phase depending on local wiring codes.
Electricians must identify blue wires correctly to ensure safety and proper function during installations or repairs. While blue wires are not usually used for grounding or neutral purposes, misidentification can lead to circuit malfunctions or safety hazards. Always de-energize circuits and verify connections with a tester before working with blue wires or any electrical wiring.
