# Two-way light switch plan mark

Canonical URL: https://eloragrid.ai/symbols/iec-two-way-light-switch
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: S2W
Drawing use: GA
Reference families: IEC

## Symbol convention

Convention: IEC
Form: Two-way switch
IEC 60617 installation-plan style (architectural and topographical installation symbols); independently drawn, not certified IEC geometry or a database identifier.

Plan mark for a two-way switch used in pairs so one lighting group can be switched from two places.

## In plain English

### What does Two-way light switch plan mark mean?

Two-way switches are installed in pairs at either end of a corridor or staircase so either switch changes the state of the lights. The IEC-style plan form draws the switch circle with strokes in two opposite directions, each with a tick, showing the changeover action.

### A simple example

On a plan the pair is linked by a switching line to the luminaire group. The electrician reads the pair to run strappers between the two switches; where an intermediate switch is shown between them, a third location can also control the lights.

### What the drawings help you do

The symbol does not show the wiring method, which can be conventional strappers or a converted arrangement. It also does not tell you the gang count unless written.

### This particular reference

Plan mark for a two-way switch used in pairs so one lighting group can be switched from two places. In US terminology this is a three-way switch; the US four-way switch corresponds to the IEC intermediate switch.

### Terms

- Schematic: A drawing showing function and connections rather than physical appearance.

Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

- [IEC graphical symbols for diagrams](https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/)
- [Elementary switching devices](https://www.electrical-installation.org/enwiki/Elementary_switching_devices)


## What it represents

Two-way switches are installed in pairs at either end of a corridor or staircase so either switch changes the state of the lights. The IEC-style plan form draws the switch circle with strokes in two opposite directions, each with a tick, showing the changeover action.
On a plan the pair is linked by a switching line to the luminaire group. The electrician reads the pair to run strappers between the two switches; where an intermediate switch is shown between them, a third location can also control the lights.
The symbol does not show the wiring method, which can be conventional strappers or a converted arrangement. It also does not tell you the gang count unless written.

## How to read it

- Expect two-way switches in pairs; a single two-way switch usually signals a drafting error or a spare.
- Look for an intermediate switch between the pair on long runs.

## Information to show or reference

- Show both switch positions and the controlled luminaires.
- Mark any intermediate switches.
- Note gang count where plates are shared.

## Important distinction

In US terminology this is a three-way switch; the US four-way switch corresponds to the IEC intermediate switch.

## Facts

- Operation: Changeover contact, used in pairs
- US equivalent term: Three-way switch
- Exact standard graphic: Not reproduced here; confirm the form against IEC 60617 and the project legend

## Public references

- [IEC graphical symbols for diagrams](https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/) — IEC. IEC graphical symbol context; independently drawn here.
- [Elementary switching devices](https://www.electrical-installation.org/enwiki/Elementary_switching_devices) — Schneider Electric — Electrical Installation Guide. Context for functional control switching.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.