Side-by-side reference

Understand the difference.

Compare the meaning, drawing context and source references of two entries. A similar graphic or shared abbreviation does not establish equivalence.

First referenceCompare with

IEC

Noiseless earth

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.

Drawing use: Schematic
Application: Connections & wiring
Reference family: IEC
Form evidence: Noiseless earth. Independent IEC-context illustration; not certified IEC geometry.

A distinction that matters

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.

Full reference

Symbols

Functional earth

Functional earth serves an operational purpose such as a documented EMC or signal-reference connection. It must be distinguished from the protective-earthing path required for exposed conductive parts.

Drawing use: SLD / Schematic
Application: Connections & wiring
Reference family: IEC / Manufacturer

A distinction that matters

A functional-earth connection does not automatically fulfil protective-earthing requirements.

Full reference

Original educational previews. Follow the source references on each full entry for the appropriate standard or selected product.