# Arc-flash point light sensor

Canonical URL: https://eloragrid.ai/symbols/arc-flash-point-sensor
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: AF
Drawing use: SLD, Schematic
Reference families: Manufacturer

Light sensor in a switchgear compartment that detects the flash of an internal arc and signals an arc-flash relay.

## In plain English

### What does Arc-flash point light sensor mean?

A point light sensor is mounted inside a switchgear compartment, such as a breaker or cable compartment, and detects the intense light of an internal arc. It is wired or fibre-connected to an arc-flash relay that usually also checks for overcurrent before tripping, so light alone from an external source does not cause a trip.

### A simple example

The drawing should show which compartment each sensor watches, because the trip zone depends on it. The symbol does not show sensitivity, field of view or the self-supervision used to detect a disconnected sensor.

### What the drawings help you do

Identify the compartment each sensor covers. Check whether trip needs light plus overcurrent. A point sensor covers one compartment; a fibre loop sensor covers a long area such as a busbar run.

### This particular reference

Light sensor in a switchgear compartment that detects the flash of an internal arc and signals an arc-flash relay. A point sensor covers one compartment; a fibre loop sensor covers a long area such as a busbar run.

### Terms

- Coil: A wound conductor that can produce a magnetic field when energised.
- 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.

- [SEL-C804 multimode arc-flash detection fibre-optic cables](https://selinc.com/products/c804/)


## What it represents

A point light sensor is mounted inside a switchgear compartment, such as a breaker or cable compartment, and detects the intense light of an internal arc. It is wired or fibre-connected to an arc-flash relay that usually also checks for overcurrent before tripping, so light alone from an external source does not cause a trip.
The drawing should show which compartment each sensor watches, because the trip zone depends on it. The symbol does not show sensitivity, field of view or the self-supervision used to detect a disconnected sensor.

## How to read it

- Identify the compartment each sensor covers.
- Check whether trip needs light plus overcurrent.

## Information to show or reference

- Locate each sensor by compartment
- Show connection to the arc relay
- State trip logic

## Important distinction

A point sensor covers one compartment; a fibre loop sensor covers a long area such as a busbar run.

## Facts

- Detected quantity: Light from an internal arc
- Typical logic: Light combined with overcurrent
- Preview: Functional illustration of the device role; not a product footprint or certified standard graphic

## Public references

- [SEL-C804 multimode arc-flash detection fibre-optic cables](https://selinc.com/products/c804/) — Schweitzer Engineering Laboratories. Public manufacturer page describing point and fibre arc-flash light sensing.

## 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.