# ANSI/IEEE thermocouple symbol

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

## Symbol convention

Convention: IEEE / ANSI
Form: Autodesk IEEE-oriented Instrumentation and Sensors form: Thermocouple
Autodesk publishes this block under its IEEE Symbol Preview. The counterpart is the matching functional concept in the library; no equivalence of every detailed standard graphic is asserted.
Related representation: [Thermocouple](https://eloragrid.ai/symbols/thermocouple)

IEEE-library thermocouple form showing the junction of two dissimilar conductors and their polarity leads.

## In plain English

### What does ANSI/IEEE thermocouple mean?

The thermocouple form shows two dissimilar conductors meeting at a measuring junction, with the free ends wired to an instrument or device that turns a measured quantity into a signal. The library offers left and right handed versions so the junction can face the process side of the drawing, and the two leads must keep their polarity all the way to the cold junction.

### A simple example

The symbol does not identify the thermocouple type (for example K, J or T), the sheath or the extension cable. Those details matter because ordinary copper wiring between the head and the instrument introduces error unless matching extension or compensating cable is used.

### What the drawings help you do

Check the thermocouple type in the instrument schedule. Verify extension cable type and polarity from the head to the input. A thermocouple generates a small voltage from a temperature difference; an RTD changes resistance and needs an excitation current.

### This particular reference

IEEE-library thermocouple form showing the junction of two dissimilar conductors and their polarity leads. A thermocouple generates a small voltage from a temperature difference; an RTD changes resistance and needs an excitation current.

### 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.

- [Autodesk IEEE Symbol Preview — Instrumentation and Sensors](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-F44D5059-4728-40BD-B9BA-0DE7CFDFAACF.htm)
- [IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams](https://standards.ieee.org/ieee/315/515/)


## What it represents

The thermocouple form shows two dissimilar conductors meeting at a measuring junction, with the free ends wired to an instrument or transducer. The library offers left and right handed versions so the junction can face the process side of the drawing, and the two leads must keep their polarity all the way to the cold junction.
The symbol does not identify the thermocouple type (for example K, J or T), the sheath or the extension cable. Those details matter because ordinary copper wiring between the head and the instrument introduces error unless matching extension or compensating cable is used.

## How to read it

- Check the thermocouple type in the instrument schedule.
- Verify extension cable type and polarity from the head to the input.

## Information to show or reference

- State thermocouple type
- Mark lead polarity
- Specify extension or compensating cable

## Important distinction

A thermocouple generates a small voltage from a temperature difference; an RTD changes resistance and needs an excitation current.

## Facts

- Convention evidence: Autodesk IEEE Symbol Preview, Instrumentation and Sensors
- Public vendor block name: HTC1L / HTC1R and vertical forms (Autodesk identifier; not an IEEE symbol number)
- Output: Millivolt signal referenced to the cold junction
- Artwork scope: Original functional illustration; exact standard glyph and compliance are not certified

## Public references

- [Autodesk IEEE Symbol Preview — Instrumentation and Sensors](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-F44D5059-4728-40BD-B9BA-0DE7CFDFAACF.htm) — Autodesk. Public IEEE-oriented Instrumentation and Sensors preview listing the Thermocouple block and its vendor identifier.
- [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.