2 wire

2 wire is used to distinguish electrical connections for measurement signals which use only two connections for carrying both the power supply and signal. The most common example is a 2 wire 4-20mA current loop output.

2 wire is also used to describe a resistive thermometer that is wired so that there is no compensation for errors caused by the connecting wire on each side of the resistive thermometer.  Therefore a 2 wire connected resistive thermometer will be less accurate than 3 wire, or 4 wire compensation method.