Extending thermocouple wires seems simple—but if it’s not done correctly, you risk compromising the accuracy of your temperature measurements. Follow these best practices to ensure your readings remain precise and reliable.
1. Use the Correct Type of Extension Wire
Always use thermocouple extension wire that matches the type of thermocouple you're using (e.g., Type K, J, T, etc.). The metals used in the extension wire must match the metals used in the thermocouple to maintain a consistent thermoelectric signal.
- Do NOT use regular copper wire. It creates unintended junctions and introduces voltage errors that will distort your readings.
2. Match Wire Polarity
Thermocouple wires are polarity-sensitive, meaning each lead has a positive and negative side made from different metals. Carefully match the correct wires when making connections—using incorrect polarity will result in incorrect temperature readings.
- Thermocouple wire insulation is usually color-coded to help identify polarity (e.g., in Type K: yellow = positive, red = negative in the U.S. standard).
3. Keep Connections Clean and Secure
Poor or corroded connections can introduce electrical noise or resistance that affects your measurement.
- Use proper connectors or terminal blocks rated for thermocouple use.
- Avoid using solder at junction points—use crimped or screw terminals made from the proper metals instead to maintain a strong and stable connection.
4. Minimize Junctions
Every junction is a potential source of error. Try to limit the number of splices or connections in the thermocouple circuit.
5. Route Away from Electrical Noise
Thermocouple signals are low voltage and can be affected by EMI (electromagnetic interference).
- Avoid running thermocouple wires parallel to power lines, motors, or other noisy electronics.
- When possible, use shielded extension wire and ground the shield at one end.
Summary:
- Use matching thermocouple extension wire
- Observe polarity and proper connections
- Avoid copper and minimize junctions
- Shield and route wires carefully
By following these best practices, you’ll preserve the integrity of your thermocouple system and ensure reliable temperature data.
Need help selecting the right extension wire or connectors for your thermocouple system? Contact us now - our team is here to help!