# Lightning protection down-conductor

Canonical URL: https://eloragrid.ai/symbols/lightning-down-conductor
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: DC
Drawing use: GA, Schematic
Reference families: IEC, IEEE / ANSI

The conductor carrying lightning current from air terminations on a structure down to the earth termination system.

## In plain English

### What does Lightning protection down-conductor mean?

Down-conductors run from the air termination network on the roof to the earth electrodes, carrying lightning current by the shortest practical path. Installation guidance describes them as part of the building protection system together with the capture device and earth leads. Elevations and roof plans show them as a distinct line style.

### A simple example

The symbol does not tell you material, cross-section or separation distance from internal services. Insufficient separation can cause side flashes into wiring. Structural steel or reinforcing used as natural down-conductors may not be drawn explicitly, so check the lightning protection design notes.

### What the drawings help you do

Check separation from internal wiring and services. Identify whether structural steel is used as a down path. A down-conductor carries lightning current to earth; a protective earth conductor carries fault current from the electrical installation.

### This particular reference

The conductor carrying lightning current from air terminations on a structure down to the earth termination system. A down-conductor carries lightning current to earth; a protective earth conductor carries fault current from the electrical installation.

### Terms

- Rating: A value stating the conditions for which equipment is specified.
- 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.

- [Building protection system](https://www.electrical-installation.org/enwiki/Building_protection_system)
- [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

Down-conductors run from the air termination network on the roof to the earth electrodes, carrying lightning current by the shortest practical path. Installation guidance describes them as part of the building protection system together with the capture device and earth leads. Elevations and roof plans show them as a distinct line style.
The symbol does not tell you material, cross-section or separation distance from internal services. Insufficient separation can cause side flashes into wiring. Structural steel or reinforcing used as natural down-conductors may not be drawn explicitly, so check the lightning protection design notes.

## How to read it

- Check separation from internal wiring and services.
- Identify whether structural steel is used as a down path.

## Information to show or reference

- Show each down-conductor route.
- State material and size.
- Show test joint and earth termination at the base.

## Important distinction

A down-conductor carries lightning current to earth; a protective earth conductor carries fault current from the electrical installation.

## Facts

- Graphic cue: Vertical line with arrow or lightning mark from roof to earth
- System role: Path from air termination to earth
- Preview: Original educational illustration; consult the publisher and applicable standard for the exact graphic

## Public references

- [Building protection system](https://www.electrical-installation.org/enwiki/Building_protection_system) — Schneider Electric, Electrical Installation Guide. Public installation-guide description of building lightning protection with down-conductors.
- [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 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.