What is a Thermocouple? Thermocouple Sensors to your Specifications

What is a Thermocouple?

A thermocouple is a simple device that is used to measure temperature. Thermocouple sensors are made from two wires joined (welded) together to form a measuring junction (also known as a hot junction). This junction is usually enclosed in a metal sheath and is inserted into the medium where the temperature is to be measured. The opposite end of the two wires are also (effectively) joined at a point known as the cold junction.

How does a thermocouple work?

As the temperature at the hot junction changes, it creates a thermal gradient between the hot and cold junctions which generates an electron flow and a resultant electromotive force (EMF), measured in Millivolts. The voltage measured at the ends of the conductors is a function of the temperature difference along the conductor length. This effect was discovered by TJ Seebeck in 1822 and is known as The Seebeck Effect.

When used with a temperature instrument, the cold junction is electronically referenced to 0ºC and a formula is applied to the millivolt signal, which is then be converted to °C or °F, using instrumentation. For a more detailed explanation of how a thermocouple works, please see our Thermocouple Theory page.

Thermocouple Sensors - Custom Built Thermocouples to your Specifications

We are the largest manufacturer of thermocouple sensors in Europe. Having an enormous range of components in stock means we can make virtually any sensor you specify. We can ship custom built thermocouples typically within 5 days or sooner.

Mineral Insulated
Mineral Insulated Thermocouple SensorsRugged sensors, ideal for most applications. Vast choice of terminations e.g. pot seals, cables, connectors, heads etc.
Swaged Tip
Swaged Tip Thermocouple SensorsFast response thermocouples ideal for industrial and other applications.
Miniature Thermocouple SensorsIdeal for precision temperature measurements where minimal displacement and a fast response is required.
Heavy Duty
Heavy Duty Thermocouple SensorsFor industrial applications such as furnaces, kilns, ovens, boliers, flues etc. Many types of sheath material available.
High Temperature Thermocouples High Temperature ThermocouplesVarious thermocouples specifically for high temperature applications. Wide choice of sheath materials and terminations. General Purpose
General Purpose ThermocouplesA wide range of thermocouples to suit many applications. Hand held, surface, bayonet, bolt, patch styles etc.
AMS2750 Approved
AMS2750 approved ThermocouplesCalibrated thermocouples designed to meet the high quality and accuracies demanded for heat treatment and vacuum furnace applications
Industrial Vacuum
vacuum Thermocouples Ceramic sheathed calibrated thermocouples designed specifically in vacuum furnace applications with very low leak rates
ATEX/IECEx Approved
ATEX approved ThermocouplesA large range of thermocouples with a variety of terminations such as pot seal, terminal heads etc.
what is a thermocouple video

Thermocouple Types

There are several different thermocouple calibration types (K Type thermocouples, J Type, T Type, N Type, Type R and Type S) each with different characteristics and covering various temperature ranges. Type K is one the most popular thermocouples used in industrial applications, due to its versatility and wide temperature range, T type thermocouples are generally preferred in applications below 0ºC and Type R thermocouples are preferred in furnace thermocouple applications. A detailed list of the different thermocouple types, thermocouple colour codes and other characteristics can be found here.


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Thermocouple Sensors
Mineral Insulated Thermocouples
Thermocouples with Mini Plug
Thermocouples with Terminal Head
Thermocouples with Cable
High Temperature Thermocouples
General Purpose Thermocouples
ATEX/IECex Thermocouple Sensors
Ceramic Thermocouple Sensors
Fast Response Thermocouple Sensors
Autoclave Thermocouple Sensors
Surface Measurement Thermocouple Sensors
FEP Insulated Thermocouple

Platinum Resistance Thermometers
Mineral Insulated RTD Pt100 Sensors
Rigid Stem RTD Pt100 Sensors
Hand Held RTD Pt100 Sensors
Surface Measurement RTD Pt100 Sensors
RTD Pt100 Sensors with Cable
RTD Pt100 Sensors with Mini Plug
Autoclave RTD Pt100 Sensors
RTD Pt100 with Terminal Head
ATEX/IECex Platinum Resistance Thermometers
Fast Response RTD Pt100 Sensors
Air Temperature RTD Pt100 Sensors
Magnetic RTD Pt100 Sensors
PVC Single Pair Thermocouple Cable
PFA Single Pair Thermocouple Cable
Fibreglass Single Pair Thermocouple Cable
PVC Multipair Thermocouple Cable
PFA Multipair Thermocouple Cable
Fibreglass Multipair Thermocouple Cable
PVC RTD Pt100 Cable
PFA RTD Pt100 Cable
Fibreglass RTD Pt100 Cable

Miniature Thermocouple Connectors
Mini Thermocouple Connectors – 220ºC Rated
Mini Thermocouple Connectors – 350ºC Rated
Mini Thermocouple Connectors – 650ºC Rated
Mini Thermocouple Connector Accessories
Mini Thermocouple Connector Panels
Mini Three Pin Connectors

Standard Thermocouple Connectors
Standard Thermocouple Connectors – 220ºC
Standard Thermocouple Connectors – 350ºC Rated
Standard Thermocouple Connectors – 650ºC Rated
Standard Thermocouple Connector Accessories
Standard Thermocouple Connector Panels
Standard Three Pin Connectors
Hand Held Indicators
Panel Indicators
Temperature Transmitters
Temperature Controllers
Temperature Programmers
Temperature Calibrators
Chart Recorders
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DIN Rail Mounted Transmitters
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ATEX/IECEx Rated Transmitters
Dry Block Calibrator
Temperature Dataloggers

Temperature Accessories
Compression Fittings
Pressure and Vacuum Feedthroughs
ATEX/IECEx Compression Fittings

UKAS Calibration Services

Pressure Gauges
Pressure Transmitters

© 1998- TC Ltd., P.O. Box 130, UXBRIDGE, UB8 2YS, United Kingdom
Tel.: 01895 252222, Fax: 01895 273540, Email:
© 1998- TC Ltd., P.O. Box 130, UXBRIDGE, UB8 2YS, United Kingdom
Tel.: 01895252222, Fax: 01895 273540, Email: