SD
Smoke detector plan symbol
Fire alarm plan symbol for a point smoke detector, drawn as a detector box with a smoke indication.
IEC
IEEE / ANSI · SD
ANSI smoke detector plan symbol
US-style plan symbol for a smoke detector: a circle or square with SD or S marking on the ceiling plan.
In plain English
What does ANSI smoke detector plan mean?
US fire alarm plans commonly draw smoke detectors as a circle tagged SD or a square with an S, with a subscript for duct or beam types. The form follows the project legend, which often adapts NFPA-based fire alarm conventions.
A simple example
Addresses and circuit numbers are written beside the symbol. The plan is checked against spacing rules for smooth and beamed ceilings and against obstructions. The tag does not distinguish photoelectric from ionisation detectors. The legend or device schedule does.
What the drawings help you do
Read subscripts for duct or beam types. Match addresses to the panel. The IEC-style smoke detector plan symbol serves the same purpose with a different internal mark.
This particular reference
US-style plan symbol for a smoke detector: a circle or square with SD or S marking on the ceiling plan. The IEC-style smoke detector plan symbol serves the same purpose with a different internal mark.
- 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 · Electrical installation design methodology and references
IEEE / ANSI · Smoke detector, US plan
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
US fire alarm plans commonly draw smoke detectors as a circle tagged SD or a square with an S, with a subscript for duct or beam types. The form follows the project legend, which often adapts NFPA-based fire alarm conventions.
Addresses and circuit numbers are written beside the symbol. The plan is checked against spacing rules for smooth and beamed ceilings and against obstructions. The tag does not distinguish photoelectric from ionisation detectors. The legend or device schedule does.
How to read it
- Read subscripts for duct or beam types.
- Match addresses to the panel.
Information to show or reference
- Tag address.
- State detector type.
- Check spacing.
A distinction that matters
The IEC-style smoke detector plan symbol serves the same purpose with a different internal mark.
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 and official status; not a source of reproduced artwork.
Electrical installation design methodology and references
Installation design context: life-safety systems are coordinated with the building electrical design.
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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