# Overhead line

Canonical URL: https://eloragrid.ai/symbols/iec-overhead-line
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: OHL
Drawing use: SLD, GA
Reference families: IEC

## Symbol convention

Convention: IEC
Form: Overhead line route form
Independent IEC-context illustration; not certified IEC geometry.

A line or route mark identifying conductors carried overhead on poles or towers rather than buried or enclosed.

## In plain English

### What does Overhead line mean?

The overhead line form identifies a circuit section strung in air between supports. On network single-line diagrams it distinguishes overhead feeders from underground cable sections, which matters because the two have different impedance, fault behaviour, auto-reclose practice and lightning exposure.

### A simple example

The symbol does not tell you the conductor type, span lengths, earth wire arrangement or structure type. Line data sheets and route drawings carry those. Where a feeder changes from overhead to underground, look for a cable sealing end or transition point drawn at the junction.

### What the drawings help you do

Note where the feeder changes between overhead and underground sections. Check whether auto-reclose is applied to feeders with overhead sections. An overhead line is strung in air; an underground cable is buried and has very different capacitance and fault characteristics.

### This particular reference

A line or route mark identifying conductors carried overhead on poles or towers rather than buried or enclosed. An overhead line is strung in air; an underground cable is buried and has very different capacitance and fault characteristics.

### 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.

- [IEC-60617 symbol preview directory](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-7871E6EF-24D5-467E-9B74-321FEDC9DFDA.htm)
- [Building protection system](https://www.electrical-installation.org/enwiki/Building_protection_system)


## What it represents

The overhead line form identifies a circuit section strung in air between supports. On network single-line diagrams it distinguishes overhead feeders from underground cable sections, which matters because the two have different impedance, fault behaviour, auto-reclose practice and lightning exposure.
The symbol does not tell you the conductor type, span lengths, earth wire arrangement or structure type. Line data sheets and route drawings carry those. Where a feeder changes from overhead to underground, look for a cable sealing end or transition point drawn at the junction.

## How to read it

- Note where the feeder changes between overhead and underground sections.
- Check whether auto-reclose is applied to feeders with overhead sections.

## Information to show or reference

- Identify conductor type and route length.
- Mark transition points to underground cable.
- Reference structure and earth-wire details on route drawings.

## Important distinction

An overhead line is strung in air; an underground cable is buried and has very different capacitance and fault characteristics.

## Facts

- Graphic cue: Line with pole or support marks along its length
- Engineering impact: Impedance, lightning exposure and reclosing practice
- Preview: Original educational illustration; consult the publisher and applicable standard for the exact graphic

## Public references

- [IEC-60617 symbol preview directory](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-7871E6EF-24D5-467E-9B74-321FEDC9DFDA.htm) — Autodesk. Public directory of IEC-oriented symbol families.
- [Building protection system](https://www.electrical-installation.org/enwiki/Building_protection_system) — Schneider Electric, Electrical Installation Guide. Public installation-guide context on lightning exposure of external conductors.

## 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.