RTD Colour Codes
RTDs are available in a wide range of styles, configurations and terminations and are available as either a 2-wire, 3-wire or 4-wire device. Each wiring configuration has its own characteristics and advantages and they are usually colour coded as below:
2-wire RTD Pt100 Sensor = 1 x red lead wire and 1 white lead wire
3-wire RTD Pt100 Sensor = 2 x red lead wires and 1 white lead wire
4-wire RTD Pt100 Sensor = 2 x red lead wires and 2 white lead wires
2, 3 and 4 Wire RTD Wiring Diagram
An insulation colour code and wiring diagram for RTD sensors is shown below.

Typical RTD Sensors - available as 2, 3 or 4 wire configuration
Resistance Thermometers (Pt100, RTD, PRT) -Mineral Insulated

Rigid Stem

Resistance Thermometers (Pt100, RTD, PRT)

for Surface Measurements

Resistance Thermometers (Pt100, RTD, PRT)
