Sinking and Sourcing

Article Published: November 24, 2021 12:23 PM
Last Updated: July 29, 2025 3:20 PM
Written by: Jack Carr

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Sinking and sourcing are terms used to describe how a load (the device being turned on or off) is powered in regards to the sensor.

Sinking is the most common and it involves the switching of load current (power) supplied by a power source external to the sensor. With this configuration, current passes through the load first, through the output switch of the sensor second and finally to ground. Sensors with sinking output switches the negative leg of the circuit.

Sourcing refers to a configuration in which the sensor is the source of the current required to power the load. In a sourcing situation, current supplied by the sensor passes through the load second and then to ground. Sensors with sourcing output switches the positive leg of the circuit.

Wet sink – The load is energised as long as the sensor tip is immersed in fluid.
Dry sink – The load is energised as long as the sensor tip is dry (not immersed in fluid).

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Jack Carr

Technical Sales & Marketing Manager, Boiswood

Jack combines deep technical expertise with hands-on experience in pressure and flow control systems. With a strong focus on real-world applications, he works closely with customers to understand their challenges and deliver fit-for-purpose solutions. His practical approach and in-depth product knowledge ensure every recommendation is accurate, efficient, and built around performance.

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