Fibreglass

Type L Fibreglass Thermocouple Wire for Industrial Temperature Measurement

The Type L fibreglass thermocouple wire connects Type L (Fe-CuNi) thermocouples to the measuring instrument and transmits the thermoelectric voltage signal with the highest accuracy. Unlike a compensating cable, the conductors are made of the same material as the wires inside the thermocouple itself. As a result, the Type L fibreglass thermocouple wire meets the tolerance limits of Tolerance Class 1 in accordance with DIN EN 60584-3, ensuring significantly lower measurement uncertainty than Tolerance Class 2 compensating cables.

The fibreglass insulation with stainless steel braid withstands ambient temperatures up to 400 degrees Celsius, surpassing standard insulations made of PTFE or PVC, which reach their limits at a maximum of 250 degrees Celsius. The stainless steel braid provides additional protection against mechanical abrasion, bending and contact with sharp-edged components. The colour coding follows DIN 43714 with a blue outer sheath, red positive conductor and blue negative conductor for reliable identification during installation.

Therma manufactures all thermocouple wires 100% by hand at its site in Germany and produces every Type L fibreglass thermocouple wire in accordance with DIN 43714 under ISO 9001 quality standards. In-house manufacturing without intermediaries enables a standard delivery time of just one week for standard configurations. Custom assemblies for project-specific requirements can also be produced at short notice.

Type L Fibreglass Thermocouple Wire in Various Lengths and Cross-Sections

The Type L fibreglass thermocouple wire is available in several AWG cross-sections that differ in conductor diameter and electrical resistance. The chosen cross-section determines over what distance the wire can transmit the thermoelectric voltage signal without significant quality loss. For cable runs exceeding 10 metres, larger cross-sections are recommended to keep voltage drop and additional measurement uncertainty to a minimum. The following overview shows common cross-sections with typical application scenarios:

AWG	Conductor Diameter	Recommended Cable Length	Typical Application
24	0.51 mm	Up to 10 m	Compact measurement points, laboratories
20	0.81 mm	Up to 25 m	Standard installations, plant engineering

For most industrial applications, AWG 20 offers the best combination of flexibility and signal quality. For particularly long cable runs or environments with strong electromagnetic interference, a larger cross-section may be advisable. Therma provides guidance on selecting the optimal cross-section for your specific installation situation and manufactures custom configurations on request.

In addition to standard cross-sections, Therma also supplies the Type L fibreglass thermocouple wire in custom lengths from 1 metre. Assembly with matching thermocouple connectors such as miniature or standard connectors is carried out directly at the factory. Orders in standard configuration are available from stock and ready for dispatch within one week.

Applications for Type L Fibreglass Thermocouple Wire in Industry

Wherever Type L thermocouples operate under elevated ambient temperatures, the Type L fibreglass thermocouple wire ensures a reliable connection to the measuring instrument. In metalworking and at heat treatment plants, temperatures along cable routes frequently range between 200 and 350 degrees Celsius. Standard wires with PTFE insulation are rated for a maximum of 250 degrees Celsius and reach their limits under these conditions. The fibreglass insulation, with its temperature rating of 400 degrees Celsius, provides sufficient headroom for continuous operation.

In the chemical and petrochemical industry, the resistance of the stainless steel braid to aggressive media and mechanical contact is an additional advantage. Piping systems, reactors and drying plants require lead wires that withstand not only thermal but also mechanical stress. At the same time, the wires must remain flexible enough to be routed along pipes and plant components. The Type L fibreglass thermocouple wire combines these properties in a compact design.

A further area of application is power generation and power plant technology, where thermocouples monitor critical process temperatures over extended periods. The lead wire must operate reliably for years without losing precision. Tolerance Class 1 of the thermocouple wire ensures that the measurement accuracy of the entire chain from sensor to display instrument is maintained.

Custom Manufacturing of Your Type L Fibreglass Thermocouple Wire

Therma has its own technical development department that manufactures individual thermocouple wires based on drawings or STEP files. Custom lengths, special cross-sections or project-specific connector terminations can be produced within 1 to 2 weeks. Special insulation requirements, such as increased temperature resistance or chemical resistance, are also implemented in individual production. For complex measurement projects, Therma specialists provide personal, no-obligation consultation.

The Type L fibreglass thermocouple wire can be fitted ex works with compression fittings made of stainless steel, brass or PTFE. Combination with miniature or standard connectors is also possible, so the wire arrives ready for installation. All custom products undergo the same quality control as standard products and meet the requirements of ISO 9001 certification.

Whether a single piece for a test stand setup or a series wire for a production plant, Therma delivers the Type L fibreglass thermocouple wire in the configuration your measurement project requires. Over 30 years of experience in temperature measurement technology and manufacturing directly at the German site guarantee short communication paths, personal contact and fast implementation.