Thermocouple Connectors - Types and Styles

Contents

1. Thermocouple and RTD Connectors
2. Function and Compatibility
3. Colour Coding and Temperature Ratings
4. Connector Accessories

While some thermocouples and RTDs (Resistance Temperature Detectors) are terminated with bare wires -commonly seen in laboratory or industrial research settings - many practical applications benefit from using connectors. Connectors simplify installation, sensor replacement, and integration with instrumentation.

Thermocouple and RTD Connectors

Miniature and standard connectors are widely used with:

• Thermocouples: Available for all standard thermocouple types (e.g., Type K, J, T). The contact materials inside the connectors are made from thermocouple-grade alloys to maintain measurement accuracy and avoid unwanted EMFs, especially where temperature differences may occur.
• RTDs: Copper-compatible connectors are used for resistance thermometer applications, ensuring reliable electrical contact and minimizing resistance errors.

Function and Compatibility

Connectors typically bridge the thermocouple or RTD assembly to extension or compensating cables, which then connect to instrumentation or reference junctions. This modular setup enables:

• Quick sensor installation and replacement
• Preservation of thermoelectric uniformity
• Secure, reliable connections

Most connector designs include:

• Locking mechanisms for secure fitment
• Polarity markings (positive and negative)
• Polarized shapes to prevent incorrect mating

Although no universal standard exists for connector design, most products are cross-compatible across major manufacturers.

Colour Coding and Temperature Ratings

Thermocouple connectors are typically colour-coded to align with IEC 60584-3 international standards, making identification easier. However, high-temperature-rated connectors may use:

• Brown or white bodies, regardless of thermocouple type
• Code letter markings (e.g., K, J, T) for thermocouple identification

This ensures users can distinguish connectors based on both type and temperature rating.

Connector Accessories

Common accessories include:

• Connector panels (standard and miniature): For organized multi-sensor connections
• Barrier terminal strips: With clearly marked alloy types and polarity, available for both thermocouples and RTD copper conductors

Further Reading

What are the various thermocouple types?
Explore the features and characteristics of the various thermocouple types

Thermocouple Output Tables
View EMF versus Temperature tables for all thermocouple types.

What are the thermocouple colour codes?
Explore thermocouple colour codes for cable and connectors.