**4.2.2 Thermocouple (heat sink) reference junction**

With accurate thermocouple measurements required, it is common practice to reference both legs to copper lead wire at the ice point so that copper leads may be connected to the emf readout instrument. This procedure avoids the generation of thermal emfs at the terminals of the readout instrument. The emf generated is dependent on a difference in temperature, so in order to make a measurement the reference must be known. The reference junction is placed in an ice water bath at a constant 0oC (32oF). Because ice baths are often inconvenient to maintain and not always practical, several alternate methods are often employed (Omega Engineering, 2001)
