SD
Dimmer switch plan mark
Plan mark for a switch that varies lamp brightness, drawn as a switch with an added variability arrow.
IEC
IEEE / ANSI · SD
ANSI dimmer switch plan symbol
US plan symbol SD for a wall dimmer controlling a lighting group.
In plain English
What does ANSI dimmer switch plan mean?
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.
A simple 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.
What the drawings help you do
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.
This particular reference
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.
- Signal
- Electrical information passed between devices, rather than necessarily the main power supply.
- Rating
- A value stating the conditions for which equipment is specified.
- Schematic
- A drawing showing function and connections rather than physical appearance.
Read the source: IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams
IEEE / ANSI · Dimmer switch, SD
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.
Shown as an independently authored educational illustration. Use the cited publication and drawing legend to verify the required drafting form.
GA · SD
What it represents
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.
How to read it
- Check dimming technology in the fixture schedule.
- Note multi-gang derating for ganged dimmers.
Information to show or reference
- State dimmer load rating.
- State control method.
- Link the dimmed group.
A distinction that matters
The IEC dimmer uses a variability arrow on a switch mark; the US form uses the D subscript.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams
Graphic-symbol standards context; not a source of reproduced artwork.
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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