{"schemaVersion":1,"slug":"iec-main-earthing-terminal","name":"Main earthing terminal","kind":"symbol","abbreviation":"MET","aliases":["main earth bar","MET","main earthing busbar"],"category":"connections-wiring","drawingTypes":["SLD","Schematic"],"referenceFamilies":["IEC"],"summary":"The terminal or bar where protective conductors, bonding conductors and the earthing conductor of an installation meet.","description":["The main earthing terminal is the hub of an installation's earthing. Installation guidance describes it as the point that provides the main equipotential connection, with the earthing conductor to the electrode, main bonding conductors to metallic services and protective conductors to circuits all landed on it. Earthing schematics draw it as a bar with labelled connections.","The symbol shows the hub but not the size of each conductor, which must be scheduled. It also does not show the removable test link, which should be drawn on the electrode connection. In larger sites, sub-main earth bars are separate items connected back to the MET."],"readingNotes":["Check that every main bonding conductor lands on the MET.","Look for the test link on the electrode conductor."],"drawingChecklist":["Label each conductor on the MET.","Show earthing conductor and test link.","Schedule bonding conductor sizes."],"distinction":"The main earthing terminal is the installation's earthing hub; a protective-earth terminal block is a single terminal in a panel.","facts":[{"label":"Graphic cue","value":"Bar with earth symbol and several labelled connections"},{"label":"Connected items","value":"Earthing conductor, main bonds and circuit protective conductors"},{"label":"Preview","value":"Original educational illustration; consult the publisher and applicable standard for the exact graphic"}],"references":[{"sourceId":"s28-eig-earthing-connections","relevance":"Public installation-guide definition of the main earthing terminal."},{"sourceId":"pub-symbol-earthing-surge","relevance":"Public IEC-oriented earth and bonding forms."}],"related":["iec-removable-earth-test-link","protective-equipotential-bonding","ga-earth-bar"],"artwork":"s28-iec-main-earthing-terminal","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","symbolVariant":{"convention":"IEC","form":"Main earthing terminal","reference":"Independent IEC-context illustration; not certified IEC geometry."},"plainEnglish":{"title":"What does Main earthing terminal mean?","introduction":"The main earthing terminal is the hub of an installation's earthing. Installation guidance describes it as the point that provides the main equipotential connection, with the earthing conductor to the electrode, main bonding conductors to metallic services and protective conductors to circuits all landed on it. Earthing schematics draw it as a bar with labelled connections.","example":"The symbol shows the hub but not the size of each conductor, which must be scheduled. It also does not show the removable test link, which should be drawn on the electrode connection. In larger sites, sub-main earth bars are separate items connected back to the MET.","drawings":"Check that every main bonding conductor lands on the MET. Look for the test link on the electrode conductor. The main earthing terminal is the installation's earthing hub; a protective-earth terminal block is a single terminal in a panel.","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":"Earthing connections","url":"https://www.electrical-installation.org/enwiki/Earthing_connections"},{"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"}],"detail":"The terminal or bar where protective conductors, bonding conductors and the earthing conductor of an installation meet. The main earthing terminal is the installation's earthing hub; a protective-earth terminal block is a single terminal in a panel.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/iec-main-earthing-terminal","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/iec-main-earthing-terminal.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"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 definition of the main earthing terminal."},{"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 bonding forms."}]}