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I have thermocouple type J. I want to connect by wiring of type K. Is it possible?

Generally, what are the recommendations for wiring thermocouples?

Anything's possible, but it won't be as accurate as if you use the correct extension cable. You will get errors due to the difference in temperature at the thermocouple end vs. the indication end. Why not use type K if you don't want to change the cable?

Roy

No you can't do that becouse you will make a new cold junction so the total mv will be wrong.

to choose the type you must know the following:
1-range
2-accuracy
3-response time

Thank you all
But in all paper they said that theoretically there is no problem for using any third homogeneous material with no effect the net emf of the circuit so long as its extremities are at the same temperature.

The papers are correct, but the real world practice is that using non-similar T/C extension wire is not usually done.

It will usually introduce a very small temperature differential (in percentage terms) which can become several degress or more at high temperatures. If you are just interested in monitoring a temperature, this is not usually a problem. If, however, you are interested in controlling a very precise temperature using non-similar T/C extension wire, then you may find this to be problematic.

You can perform your own tests and verification, also, to determine the error (if any can be detected) of using non-similar T/C extension wire for your specific application.

Let us know how your testing turns out!

It's true in one case if you put the connection ( cold junction) in ice