Side-by-side reference

Understand the difference.

Compare the meaning, drawing context and source references of two entries. A similar graphic or shared abbreviation does not establish equivalence.

First referenceCompare with

IEEE / ANSI

ANSI three-way switch plan symbol

The US three-way switch is drawn as S with subscript 3. Two S3 symbols appear on the plan at different entries, connected by switch legs to the same lighting group, and the installer runs travellers between them.

Drawing use: GA
Application: Installation & communications
Reference family: IEEE / ANSI
Form evidence: Three-way switch, S3. US architectural electrical plan practice in the ANSI Y32.9 lineage, read alongside IEEE 315 context; independently drawn, not a certified IEEE or ANSI graphic.

A distinction that matters

S4 is a four-way intermediate device; S3 is the changeover switch used at the ends.

Full reference

S2W

IEC

Two-way light switch plan mark

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.

Drawing use: GA
Application: Installation & communications
Reference family: IEC
Form evidence: Two-way switch. IEC 60617 installation-plan style (architectural and topographical installation symbols); independently drawn, not certified IEC geometry or a database identifier.

A distinction that matters

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

Full reference

Original educational previews. Follow the source references on each full entry for the appropriate standard or selected product.