# Noiseless earth

Canonical URL: https://eloragrid.ai/symbols/iec-noiseless-earth
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: -
Drawing use: Schematic
Reference families: IEC

## Symbol convention

Convention: IEC
Form: Noiseless earth
Independent IEC-context illustration; not certified IEC geometry.

An earth connection specifically designated as low-noise, used for sensitive measurement and electronics references.

## In plain English

### What does Noiseless earth mean?

The noiseless or clean earth symbol identifies a connection to an earth that is kept free of noise from power circuits, usually an instrument earth bar connected to the main earthing system at a single point. It is drawn as an earth symbol enclosed in a circle or with a distinguishing mark.

### A simple example

A noiseless earth is not a separate earth electrode. Separate electrodes not bonded to the main earth create dangerous potential differences during faults. The symbol identifies the bar and its single-point connection, which the earthing diagram should show.

### What the drawings help you do

Find the single point where the clean earth joins the main earth. Reject any isolated clean earth electrode. A noiseless earth is a dedicated low-noise bar bonded to the main earth; a functional earth is any earth used for operation rather than safety.

### This particular reference

An earth connection specifically designated as low-noise, used for sensitive measurement and electronics references. A noiseless earth is a dedicated low-noise bar bonded to the main earth; a functional earth is any earth used for operation rather than safety.

### Terms

- Terminal: An identified point where a conductor connects.
- 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.

- [AutoCAD Electrical: Earthing, sources and surge protection](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-1E3FDEAE-B4B2-417C-8075-108AA2C6E509.htm)
- [Earthing connections](https://www.electrical-installation.org/enwiki/Earthing_connections)


## What it represents

The noiseless or clean earth symbol identifies a connection to an earth that is kept free of noise from power circuits, usually an instrument earth bar connected to the main earthing system at a single point. It is drawn as an earth symbol enclosed in a circle or with a distinguishing mark.
A noiseless earth is not a separate earth electrode. Separate electrodes not bonded to the main earth create dangerous potential differences during faults. The symbol identifies the bar and its single-point connection, which the earthing diagram should show.

## How to read it

- Find the single point where the clean earth joins the main earth.
- Reject any isolated clean earth electrode.

## Information to show or reference

- Show the clean earth bar and its bond.
- Keep power returns off the clean earth.
- Label which circuits use it.

## Important distinction

A noiseless earth is a dedicated low-noise bar bonded to the main earth; a functional earth is any earth used for operation rather than safety.

## Facts

- Graphic cue: Earth symbol enclosed in a circle
- Safety rule: Must still be bonded to the main earthing system
- Preview: Original educational illustration; consult the publisher and applicable standard for the exact graphic

## Public references

- [AutoCAD Electrical: Earthing, sources and surge protection](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-1E3FDEAE-B4B2-417C-8075-108AA2C6E509.htm) — Autodesk. Public IEC-oriented earth and functional-earth forms.
- [Earthing connections](https://www.electrical-installation.org/enwiki/Earthing_connections) — Schneider Electric, Electrical Installation Guide. Public installation-guide earthing connection elements.

## 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.