# ANSI/IEEE spark gap symbol

Canonical URL: https://eloragrid.ai/symbols/ansi-spark-gap
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: SG
Drawing use: Schematic
Reference families: IEEE / ANSI, Manufacturer

## Symbol convention

Convention: IEEE / ANSI
Form: Autodesk IEEE-oriented spark gap form
Autodesk publishes this block under IEEE Symbol Preview: Miscellaneous. The counterpart is the matching functional concept; no equivalence of every detailed standard graphic is asserted.
Related representation: [Spark-gap protective element](https://eloragrid.ai/symbols/spark-gap-protective-element)

IEEE-oriented spark gap drawn as two facing electrodes separated by an air gap, which breaks down at high voltage.

## In plain English

### What does ANSI/IEEE spark gap mean?

A spark gap is a pair of electrodes separated by a gap that flashes over when the voltage exceeds its breakdown level. It appears in surge protection of telecom and control circuits and on older equipment as coordinating gaps. The publisher's IEEE miscellaneous preview lists a spark gap form, the counterpart of the existing IEC page.

### A simple example

This illustration is independent and not the IEEE graphic. A plain spark gap can sustain follow current after breakdown on power circuits, which is why power arresters use other technology. The breakdown voltage depends on gap spacing and conditions, and must be specified.

### What the drawings help you do

Check whether follow current could be sustained on the circuit. Read breakdown voltage from equipment data. A spark gap is a simple breakdown element; a gas discharge tube encloses the gap in gas for a defined breakdown.

### This particular reference

IEEE-oriented spark gap drawn as two facing electrodes separated by an air gap, which breaks down at high voltage. A spark gap is a simple breakdown element; a gas discharge tube encloses the gap in gas for a defined breakdown.

### 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.

- [Autodesk IEEE Symbol Preview — Miscellaneous](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-34282BFD-7B8E-48F3-A6ED-93ADBDDDFBD3.htm)
- [IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams](https://standards.ieee.org/ieee/315/515/)


## What it represents

A spark gap is a pair of electrodes separated by a gap that flashes over when the voltage exceeds its breakdown level. It appears in surge protection of telecom and control circuits and on older equipment as coordinating gaps. The publisher's IEEE miscellaneous preview lists a spark gap form, the counterpart of the existing IEC page.
This illustration is independent and not the IEEE graphic. A plain spark gap can sustain follow current after breakdown on power circuits, which is why power arresters use other technology. The breakdown voltage depends on gap spacing and conditions, and must be specified.

## How to read it

- Check whether follow current could be sustained on the circuit.
- Read breakdown voltage from equipment data.

## Information to show or reference

- State breakdown voltage.
- Show the protected and earthed sides.
- Use an arrester where follow current is a risk.

## Important distinction

A spark gap is a simple breakdown element; a gas discharge tube encloses the gap in gas for a defined breakdown.

## Facts

- Convention evidence: Autodesk IEEE Symbol Preview: Miscellaneous (Spark Gap)
- Public vendor block name: HFU1_S00371 (Autodesk identifier; not an IEEE symbol number)
- Standards context: IEEE/ANSI 315-1975 covers diagram graphics; IEEE lists this edition as Inactive-Reserved.
- Preview: Original educational illustration; consult the publisher and applicable standard for the exact graphic

## Public references

- [Autodesk IEEE Symbol Preview — Miscellaneous](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-34282BFD-7B8E-48F3-A6ED-93ADBDDDFBD3.htm) — Autodesk. Exact public IEEE-oriented category page listing the spark gap form.
- [IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams](https://standards.ieee.org/ieee/315/515/) — IEEE Standards Association. Graphic-symbol standards context and official status; not a source of reproduced artwork.

## 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.