SI
Intermediate light switch plan mark
Plan mark for an intermediate switch inserted between two two-way switches to add a third control point.
IEC
IEC · S2W
Two-way light switch plan mark
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.
- Schematic
- A drawing showing function and connections rather than physical appearance.
Read the source: IEC graphical symbols for diagrams · Elementary switching devices
IEC · Two-way switch
IEC 60617 installation-plan style (architectural and topographical installation symbols); independently drawn, not certified IEC geometry or a database identifier.
Shown as an independently authored educational illustration. Use the cited publication and drawing legend to verify the required drafting form.
GA · S2W
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.
A distinction that matters
In US terminology this is a three-way switch; the US four-way switch corresponds to the IEC intermediate switch.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
IEC graphical symbols for diagrams
IEC graphical symbol context; independently drawn here.
Elementary switching devices
Context for functional control switching.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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