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.
IEC
IEC · SI
Intermediate light switch plan mark
Plan mark for an intermediate switch inserted between two two-way switches to add a third control point.
In plain English
What does Intermediate light switch plan mark mean?
An intermediate switch reverses the connection of the two strapping conductors between a pair of two-way switches, so any number of intermediate switches can be added along a corridor. The plan form uses crossing strokes through the switch circle to suggest the crossover action.
A simple example
On long corridors, open-plan stairs and large rooms with several doors, plans show two two-way switches at the ends and intermediate switches at the middle doors. Reading the switching lines confirms which group each set controls.
What the drawings help you do
The symbol does not give contact arrangement detail or rating. Its presence also implies four-core or two-strapper wiring, which the installer must plan for.
This particular reference
Plan mark for an intermediate switch inserted between two two-way switches to add a third control point. A two-way switch has a changeover contact; an intermediate switch crosses two strappers and is useless without two-way switches either side.
- Normally open / normally closed
- The contact state in the normal condition defined for the drawing.
- Terminal
- An identified point where a conductor connects.
- Rating
- A value stating the conditions for which equipment is specified.
Read the source: IEC graphical symbols for diagrams
IEC · Intermediate 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 · SI
What it represents
An intermediate switch reverses the connection of the two strapping conductors between a pair of two-way switches, so any number of intermediate switches can be added along a corridor. The plan form uses crossing strokes through the switch circle to suggest the crossover action.
On long corridors, open-plan stairs and large rooms with several doors, plans show two two-way switches at the ends and intermediate switches at the middle doors. Reading the switching lines confirms which group each set controls.
The symbol does not give contact arrangement detail or rating. Its presence also implies four-core or two-strapper wiring, which the installer must plan for.
How to read it
- Confirm the run has two-way switches at each end.
- Count control points to check the number of intermediates.
Information to show or reference
- Show the two end switches and every intermediate.
- Link all to the controlled luminaires.
- Allow for strapper wiring in the cable schedule.
A distinction that matters
A two-way switch has a changeover contact; an intermediate switch crosses two strappers and is useless without two-way switches either side.
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.
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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