{"schemaVersion":1,"slug":"iec-noiseless-earth","name":"Noiseless earth","kind":"symbol","abbreviation":"-","aliases":["clean earth","low-noise earth","instrument earth"],"category":"connections-wiring","drawingTypes":["Schematic"],"referenceFamilies":["IEC"],"summary":"An earth connection specifically designated as low-noise, used for sensitive measurement and electronics references.","description":["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."],"readingNotes":["Find the single point where the clean earth joins the main earth.","Reject any isolated clean earth electrode."],"drawingChecklist":["Show the clean earth bar and its bond.","Keep power returns off the clean earth.","Label which circuits use it."],"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":[{"label":"Graphic cue","value":"Earth symbol enclosed in a circle"},{"label":"Safety rule","value":"Must still be bonded to the main earthing system"},{"label":"Preview","value":"Original educational illustration; consult the publisher and applicable standard for the exact graphic"}],"references":[{"sourceId":"pub-symbol-earthing-surge","relevance":"Public IEC-oriented earth and functional-earth forms."},{"sourceId":"s28-eig-earthing-connections","relevance":"Public installation-guide earthing connection elements."}],"related":["functional-earth","iec-screened-conductor-with-earthed-screen","iec-main-earthing-terminal"],"artwork":"s28-iec-noiseless-earth","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","symbolVariant":{"convention":"IEC","form":"Noiseless earth","reference":"Independent IEC-context illustration; not certified IEC geometry."},"plainEnglish":{"title":"What does Noiseless earth mean?","introduction":"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.","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.","drawings":"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.","terms":[{"name":"Terminal","meaning":"An identified point where a conductor connects."},{"name":"Schematic","meaning":"A drawing showing function and connections rather than physical appearance."}],"diagram":"flow","steps":["Identify the device and form","Read the connections and state","Check the equipment reference"],"caption":"A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.","sources":[{"label":"AutoCAD Electrical: Earthing, sources and surge protection","url":"https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-1E3FDEAE-B4B2-417C-8075-108AA2C6E509.htm"},{"label":"Earthing connections","url":"https://www.electrical-installation.org/enwiki/Earthing_connections"}],"detail":"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.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/iec-noiseless-earth","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/iec-noiseless-earth.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"pub-symbol-earthing-surge","title":"AutoCAD Electrical: Earthing, sources and surge protection","publisher":"Autodesk","url":"https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-1E3FDEAE-B4B2-417C-8075-108AA2C6E509.htm","type":"cad-reference","scope":"Public vendor catalogue naming and functional variants. Vendor block names are not IEC identifiers. Linked for reference; no graphics or CAD files are redistributed.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"Public IEC-oriented earth and functional-earth forms."},{"id":"s28-eig-earthing-connections","title":"Earthing connections","publisher":"Schneider Electric, Electrical Installation Guide","url":"https://www.electrical-installation.org/enwiki/Earthing_connections","type":"manufacturer","scope":"Definitions of earth electrode, main earthing terminal, removable test link and bonding conductors in an installation earthing arrangement.","checkedOn":"2026-10-28","reuse":"link-only","relevance":"Public installation-guide earthing connection elements."}]}