# ANSI smoke detector plan symbol

Canonical URL: https://eloragrid.ai/symbols/ansi-smoke-detector-plan-symbol
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: SD
Drawing use: GA
Reference families: IEEE / ANSI

## Symbol convention

Convention: IEEE / ANSI
Form: 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.

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.

### Terms

- Schematic: A drawing showing function and connections rather than physical appearance.

Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

- [IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams](https://standards.ieee.org/ieee/315/515/)
- [Electrical installation design methodology and references](https://www.electrical-installation.org/enwiki/General_rules_of_electrical_installation_design)


## 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.

## Important distinction

The IEC-style smoke detector plan symbol serves the same purpose with a different internal mark.

## Facts

- Graphic form: Circle or square tagged SD
- Legend basis: Project fire alarm legend
- Artwork scope: Original educational illustration; the exact ANSI or IEEE graphic and compliance are not certified

## Public references

- [IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams](https://standards.ieee.org/ieee/315/515/) — IEEE Standards Association. Graphic-symbol standards context and official status; not a source of reproduced artwork.
- [Electrical installation design methodology and references](https://www.electrical-installation.org/enwiki/General_rules_of_electrical_installation_design) — Schneider Electric — Electrical Installation Guide. Installation design context: life-safety systems are coordinated with the building electrical design.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.