# Main earthing terminal

Canonical URL: https://eloragrid.ai/symbols/iec-main-earthing-terminal
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: MET
Drawing use: SLD, Schematic
Reference families: IEC

## Symbol convention

Convention: IEC
Form: Main earthing terminal
Independent IEC-context illustration; not certified IEC geometry.

The terminal or bar where protective conductors, bonding conductors and the earthing conductor of an installation meet.

## In plain English

### What does Main earthing terminal mean?

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.

### A simple 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.

### What the drawings help you do

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.

### This particular reference

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.

### 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.

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


## What it represents

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.

## How to read it

- Check that every main bonding conductor lands on the MET.
- Look for the test link on the electrode conductor.

## Information to show or reference

- Label each conductor on the MET.
- Show earthing conductor and test link.
- Schedule bonding conductor sizes.

## Important distinction

The main earthing terminal is the installation's earthing hub; a protective-earth terminal block is a single terminal in a panel.

## Facts

- Graphic cue: Bar with earth symbol and several labelled connections
- Connected items: Earthing conductor, main bonds and circuit protective conductors
- Preview: Original educational illustration; consult the publisher and applicable standard for the exact graphic

## Public references

- [Earthing connections](https://www.electrical-installation.org/enwiki/Earthing_connections) — Schneider Electric, Electrical Installation Guide. Public installation-guide definition of the main earthing terminal.
- [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 bonding forms.

## 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.