What circuit does this hand-drawn diagram show?

A 120V light circuit fed from a panel, with two switch boxes controlling a light box — a three-way switch setup, apparently for a stairway (a stair-step outline is drawn between the two switch boxes).

What wire colors are used in this diagram?

Black (120V hot from the panel and the hot return to the light), Red and Blue as travelers between the switch boxes, and White as the neutral wire. In two spots the original color label was crossed out and changed to Blue.

Where does power originate in this diagram?

From the box labeled 'Panel' at the bottom, which supplies the '120V Black Hot' wire and the 'White Wire (Neutral)'.

Where are wire nuts used in this diagram?

Wire nuts are marked inside the Light Box (joining conductors at the fixture) and inside the lower Switch Box.

Which wire carries power to the light fixture when the switches are on?

The wire labeled 'Black Hot (Return)' running from the upper switch box to the Light Box.

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Hand-Drawn 3-Way Switch Wiring Diagram - 120V Stairway Light Circuit Sketch

Hand-drawn light and switch wiring diagram with light box, switch boxes and wire nuts

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Hand-drawn electrical wiring diagram of a light and switch circuit with color-coded conductors, wire nuts and panel.

AI caption January 2012 · Photo 2661 of 2964

This document is a hand-drawn wiring sketch (pen on paper) showing a 120-volt light circuit controlled by two switches (a three-way switch arrangement). At the bottom is a box labeled 'Panel,' from which a 120V Black Hot wire and a White Wire (Neutral) run up to a 'Switch Box.' Inside that switch box a wire nut joins conductors, and a Red wire and a Blue wire (the word 'Black' is crossed out and replaced with 'Blue') act as travelers running to a second 'Switch Box' at the upper left, drawn across a stair-step outline suggesting the switches are at the top and bottom of a staircase. From the upper switch box, a 'Black Hot (Return)' wire runs to the 'Light Box,' where wire nuts connect the fixture. The White (Neutral) wire runs from the panel through to the light box. Labels note wire colors (Black, Red, Blue, White) and the function of each conductor (hot, return, neutral, travelers). This is household electrical wiring, not vehicle wiring — a reader can learn how the sketch's author routed hot, neutral, and traveler wires for a stairway light on two three-way switches.

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Frequently asked questions

What circuit does this hand-drawn diagram show?: A 120V light circuit fed from a panel, with two switch boxes controlling a light box — a three-way switch setup, apparently for a stairway (a stair-step outline is drawn between the two switch boxes).
What wire colors are used in this diagram?: Black (120V hot from the panel and the hot return to the light), Red and Blue as travelers between the switch boxes, and White as the neutral wire. In two spots the original color label was crossed out and changed to Blue.
Where does power originate in this diagram?: From the box labeled 'Panel' at the bottom, which supplies the '120V Black Hot' wire and the 'White Wire (Neutral)'.
Where are wire nuts used in this diagram?: Wire nuts are marked inside the Light Box (joining conductors at the fixture) and inside the lower Switch Box.
Which wire carries power to the light fixture when the switches are on?: The wire labeled 'Black Hot (Return)' running from the upper switch box to the Light Box.