Electrical

How 3-Way Light Switches Work

Electrical Diagrams · made in Skemio

Ladder circuit diagram showing a 120 V AC source powering a rung with a 15A fuse, two SPDT switches in series, and a 60W lamp.
Ladder circuit diagram showing a 120 V AC source powering a rung with a 15A fuse, two SPDT switches in series, and a 60W lamp.
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What it shows

  • Two SPDT switches route current across dual traveler lines.
  • Flipping either switch alternates circuit continuity instantly.
  • Prevents dangerous back-feeding while keeping switching independent.

The takeaway

3-way switches act as physical XOR gates that toggle lighting states from two distinct points.

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