In a message dated 12/28/03 6:24:38 PM, lalofs@RCN.COM writes:

<< the type of wire can be important.  The thermocouple probe itself is a
junction where two
different metals meet, typically just melted together in a small bead.
It produces a VERY small voltage roughly proportional to temperature. >>

Any extension conductors from the thermocouple head to the associated
instrumentation/controller are ALL important and must be the same metals as the
thermocouple.  This can be an expensive proposition considering the noble metals
which are needed for certain types of thermocouples.  Swapping the leads as
sometime happens because of color coding variations, can wreak more havoc than
running copper wire to the thermocouple.  The potential produced is very small
and very nonlinearly proportional to the temperature.

George