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.