{"schemaVersion":1,"slug":"ansi-dimmer-switch","name":"ANSI dimmer switch plan symbol","kind":"symbol","abbreviation":"SD","aliases":["SD switch","dimmer symbol","dimming wall switch"],"category":"installation-communications","drawingTypes":["GA"],"referenceFamilies":["IEEE / ANSI"],"summary":"US plan symbol SD for a wall dimmer controlling a lighting group.","description":["A wall dimmer in US plan practice is drawn as S with subscript D, sometimes with a wattage note. The switch leg links it to the dimmed group, and three-way dimming is shown by pairing SD with S3 or with a companion device.","The reader should check dimmer type against LED driver compatibility, and whether the dimmer controls a low-voltage 0-10 V signal or switches line power directly. The plan symbol is identical for both. SD does not specify dimming technology, load or whether multi-gang derating applies."],"readingNotes":["Check dimming technology in the fixture schedule.","Note multi-gang derating for ganged dimmers."],"drawingChecklist":["State dimmer load rating.","State control method.","Link the dimmed group."],"distinction":"The IEC dimmer uses a variability arrow on a switch mark; the US form uses the D subscript.","facts":[{"label":"Graphic form","value":"S with subscript D"},{"label":"Key check","value":"Driver compatibility"},{"label":"Artwork scope","value":"Original educational illustration; the exact ANSI or IEEE graphic and compliance are not certified"}],"references":[{"sourceId":"ieee-315","relevance":"Graphic-symbol standards context; not a source of reproduced artwork."}],"related":["iec-dimmer-switch","ansi-single-pole-switch"],"artwork":"s28-ansi-dimmer-switch","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","symbolVariant":{"convention":"IEEE / ANSI","form":"Dimmer switch, SD","reference":"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."},"plainEnglish":{"title":"What does ANSI dimmer switch plan mean?","introduction":"A wall dimmer in US plan practice is drawn as S with subscript D, sometimes with a wattage note. The switch leg links it to the dimmed group, and three-way dimming is shown by pairing SD with S3 or with a companion device.","example":"The reader should check dimmer type against LED driver compatibility, and whether the dimmer controls a low-voltage 0-10 V signal or switches line power directly. The plan symbol is identical for both. SD does not specify dimming technology, load or whether multi-gang derating applies.","drawings":"Check dimming technology in the fixture schedule. Note multi-gang derating for ganged dimmers. The IEC dimmer uses a variability arrow on a switch mark; the US form uses the D subscript.","terms":[{"name":"Signal","meaning":"Electrical information passed between devices, rather than necessarily the main power supply."},{"name":"Rating","meaning":"A value stating the conditions for which equipment is specified."},{"name":"Schematic","meaning":"A drawing showing function and connections rather than physical appearance."}],"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":"IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams","url":"https://standards.ieee.org/ieee/315/515/"}],"detail":"US plan symbol SD for a wall dimmer controlling a lighting group. The IEC dimmer uses a variability arrow on a switch mark; the US form uses the D subscript.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/ansi-dimmer-switch","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/ansi-dimmer-switch.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"ieee-315","title":"IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams","publisher":"IEEE Standards Association","url":"https://standards.ieee.org/ieee/315/515/","type":"standard","scope":"Graphic symbols and designation letters. IEEE lists this edition as Inactive-Reserved; it is a historical reference, not a claim of current compliance.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"Graphic-symbol standards context; not a source of reproduced artwork."}]}