{"schemaVersion":1,"slug":"iec-intermediate-light-switch","name":"Intermediate light switch plan mark","kind":"symbol","abbreviation":"SI","aliases":["intermediate switch","four-way switch (US term)","cross switch"],"category":"installation-communications","drawingTypes":["GA"],"referenceFamilies":["IEC"],"summary":"Plan mark for an intermediate switch inserted between two two-way switches to add a third control point.","description":["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."],"readingNotes":["Confirm the run has two-way switches at each end.","Count control points to check the number of intermediates."],"drawingChecklist":["Show the two end switches and every intermediate.","Link all to the controlled luminaires.","Allow for strapper wiring in the cable schedule."],"distinction":"A two-way switch has a changeover contact; an intermediate switch crosses two strappers and is useless without two-way switches either side.","facts":[{"label":"Operation","value":"Crossover of two strapping conductors"},{"label":"US equivalent term","value":"Four-way switch"},{"label":"Exact standard graphic","value":"Not reproduced here; confirm the form against IEC 60617 and the project legend"}],"references":[{"sourceId":"iec-diagrams","relevance":"IEC graphical symbol context; independently drawn here."}],"related":["iec-two-way-light-switch","ansi-four-way-switch"],"artwork":"s28-iec-intermediate-light-switch","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","symbolVariant":{"convention":"IEC","form":"Intermediate switch","reference":"IEC 60617 installation-plan style (architectural and topographical installation symbols); independently drawn, not certified IEC geometry or a database identifier."},"plainEnglish":{"title":"What does Intermediate light switch plan mark mean?","introduction":"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.","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.","drawings":"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.","terms":[{"name":"Normally open / normally closed","meaning":"The contact state in the normal condition defined for the drawing."},{"name":"Terminal","meaning":"An identified point where a conductor connects."},{"name":"Rating","meaning":"A value stating the conditions for which equipment is specified."}],"diagram":"flow","steps":["Identify the device and form","Read the connections and state","Check the equipment reference"],"caption":"A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.","sources":[{"label":"IEC graphical symbols for diagrams","url":"https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/"}],"detail":"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.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/iec-intermediate-light-switch","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/iec-intermediate-light-switch.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"iec-diagrams","title":"IEC graphical symbols for diagrams","publisher":"IEC","url":"https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/","type":"standard","scope":"IEC 60617 and related symbol-design publications. Full database access requires a subscription.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"IEC graphical symbol context; independently drawn here."}]}