Insulated thermocouple wire is single pair wire that can be made into a thermocouple. More specifically, it is the wire from the sensing junction, to the point of cold junction compensation. Thermocouple wire is made from two dissimilar metals conductors that are joined (welded) together at the sensing end. Different metal wires are used for the various types of thermocouple types (J, K, T, E, etc). These dissimilar metals produce a millivolt electrical signal at the cold junction that is proportional to the change in temperature at the sensing end. Thermocouple wire has two grades; standard and Special Limits of Error (SLE). Special Limits of Error wire is made of the same metals as standard wire, but uses a higher grade with increased accuracy and higher expense than standard thermocouple wire.
Thermocouple wire is almost always insulated. Insulation varies from low temp (Nylon, FEP Teflon, TFE Teflon, PFA Teflon, Kapton) to high temp (fiberglass, Hi-Temp fiberglass, Refrasil, Ceramic Fiber). Thermocouple wire is typically sold in 1000' spools, but can be sold in small quantities as well.
Thermocouple extension wire is a single pair wire that cannot be made into a thermocouple, but is used to carry the signal from a thermocouple to the recorder, controller, or instrument reading the signal. Extension grade wire is used to carry a signal representing the higher temperature seen by the sensing location, but extension wire itself cannot be generally exposed to those higher temperatures. Extension wire cannot be used to make a thermocouple, but thermocouple wire can be used as extension wire. Insulation is typically PVC, but other option are available.
Multi-pair extension wire is simply more than a single pair in the same jacket. It is extension only and is usually available in 2,4,6,8,12,16,24 pairs. It is used primarily when a contractor has to run multiple runs of wire. It allows them to run one piece of wire rather than multiple individual runs.
For more information on all varieties of thermocouple wire, contact Duro-Sense by calling 310-533-6877 or visiting
https://duro-sense.com.
