# Optical fibre cable

Canonical URL: https://eloragrid.ai/symbols/optical-fibre-cable
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: OF
Drawing use: Schematic, SLD
Reference families: IEC, IEEE / ANSI

A cable line carrying light rather than current, used for protection signalling, SCADA links and substation process bus.

## In plain English

### What does Optical fibre cable mean?

The optical fibre cable representation marks a link that carries light signals. In power systems it is used for line differential protection signalling, IEC 61850 station and process bus networks, and links between buildings where electrical separation without a direct conducting path avoids earth potential rise problems. It is commonly drawn with a distinct line style or a small light-path mark on the conductor.

### A simple example

Because the fibre carries no current, it must never be read as a power or earth path. The drawing should still give the fibre count, fibre type (single mode or multimode) and connector types at each end. Spare fibres and splice points are tracked in a fibre schedule rather than on the schematic.

### What the drawings help you do

Do not treat the fibre as an electrical path for earthing or interlocking. Check fibre type and count against the equipment ports. An optical fibre cable carries light and gives electrical separation without a direct conducting path; a coaxial cable carries electrical signals and can transfer earth potential.

### This particular reference

A cable line carrying light rather than current, used for protection signalling, SCADA links and substation process bus. An optical fibre cable carries light and gives electrical separation without a direct conducting path; a coaxial cable carries electrical signals and can transfer earth potential.

### Terms

- Normally open / normally closed: The contact state in the normal condition defined for the drawing.
- Terminal: An identified point where a conductor connects.
- Signal: Electrical information passed between devices, rather than necessarily the main power supply.

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)
- [IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams](https://standards.ieee.org/ieee/315/515/)


## What it represents

The optical fibre cable representation marks a link that carries light signals. In power systems it is used for line differential protection signalling, IEC 61850 station and process bus networks, and links between buildings where galvanic isolation avoids earth potential rise problems. It is commonly drawn with a distinct line style or a small light-path mark on the conductor.
Because the fibre carries no current, it must never be read as a power or earth path. The drawing should still give the fibre count, fibre type (single mode or multimode) and connector types at each end. Spare fibres and splice points are tracked in a fibre schedule rather than on the schematic.

## How to read it

- Do not treat the fibre as an electrical path for earthing or interlocking.
- Check fibre type and count against the equipment ports.

## Information to show or reference

- State single mode or multimode and fibre count.
- Identify connector type at each end.
- Reference splice trays and patch panels in the fibre schedule.

## Important distinction

An optical fibre cable carries light and gives galvanic isolation; a coaxial cable carries electrical signals and can transfer earth potential.

## Facts

- Graphic cue: Line with optical path mark or distinct fibre line style
- Electrical property: Non-conducting; provides galvanic isolation
- 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.
- [IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams](https://standards.ieee.org/ieee/315/515/) — IEEE Standards Association. Standards context for transmission-path graphics.

## 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.