19. June 2026

Proper grounding in electrochemical measurements

Anyone working with potentiostats requires a stable measurement setup with low interference. This includes not only the correct device. Grounding, shielding, cable routing, and the position of the electrochemical cell also influence measurement quality.

If a cell is not properly grounded or is set up unfavorably, mains hum, electromagnetic interference, or ground loops can occur. This results in fluctuating readings, irreproducible results, or apparent signal curves that do not originate from the sample.

Why is proper grounding important for potentiostats?

An electrochemical cell reacts sensitively to environmental interference. The reference electrode, in particular, can pick up electromagnetic fields. This can distort signals before they are processed by the potentiostat.

Subsequent filtering or oversampling can only compensate for such interference to a limited extent. If the input signal is already disturbed or an amplifier saturates, even a computationally smoothed average will no longer provide reliable information.

Therefore: Interference should be avoided before measurement if possible.

Typical Sources of Interference in the Laboratory

Many disturbances arise from the immediate vicinity of the measurement cell. Electrical lines, high-power devices, and ungrounded metal parts are particularly critical.

Common sources of interference include:

Power lines near the cell
Cable ducts or concealed wiring
Magnetic stirrers
Frequency converters
Melting furnaces
Ballasts
Fluorescent tubes
Converters
Computers and peripheral devices
Metal frames, racks, or steel shelves
Strong radio sources or RF fields

The electrochemical cell should therefore be placed as far as possible from power transformers, power lines, and electrical control panels. The connected computer should also not be placed directly next to the potentiostat, cell, or analog instruments.

What is mains hum?

Mains hum is caused by interference from the power grid. In Europe, the mains frequency is 50 Hz. In electrochemical measurements, this signal can couple into the measurement cell or the lines.
In digital measurement curves, mains hum does not always appear as a fast oscillation. Due to unfavorable sampling, it can appear as a seemingly slow wave. This can act like a drift or a periodic measurement error.

This is problematic because the cause is easily misinterpreted. The disturbance then lies not in the sample or electrode, but in the measurement setup.

How to properly ground an electrochemical cell?

Proper grounding does not mean making as many connections to ground as possible. Crucial is controlled grounding without loops.

It is important to:

Ground metal parts near the cell specifically
Check racks, steel shelves, and metal frames
Keep ground leads as short as possible
Avoid closed ground loops
Ground shields correctly
Do not use reference electrode shielding as grounding

Ground loops, also known as ring grounds, can themselves become sources of interference. They act like antennas and pick up hum interference. Therefore, grounding should be as clear and loop-free as possible.

Particularly important: The shielding of the reference electrode cable must not be used to ground a Faraday cage or other metal parts. This shielding is at virtual ground. An incorrect connection to the measurement ground can lead to potentiostat malfunctions.

When is a Faraday cage useful?

A Faraday cage is not required for every measurement. However, it may be necessary when very sensitive measurement signals are being acquired.

Cell shielding is particularly useful for:

very small currents
poorly conductive electrolytes
long electrolyte bridges
reference electrodes with high internal resistance
strong electrical interference fields in the environment

For small currents in the µA range, even minor interference can affect the measurement result. High-impedance reference electrodes also make the setup more sensitive. In such cases, metallic shielding can improve measurement stability.

The cage or shielding must always be correctly grounded. No ground loops must be created in the process.

What role does cable routing play?

Cable routing is a common cause of interference. Cell cables should be kept as short as possible and not run parallel to power lines. The longer a cable is, the more capacities, inductances, and interference can affect the measurement.

For a stable measurement setup:

Do not extend cell cables if possible
Route working electrode cables and counter electrode cables close together
Shield reference electrode cables
Lay ground leads without loops
Separate power lines from measurement lines
Keep cable paths clear and short

Especially with high-frequency signals or steep-edged square wave signals, long cables can impair the control performance of the potentiostat.

Why is the working electrode critical?

For the working electrode, the current path and potential measurement path are routed separately. Both leads must be brought together as close to the cell as possible. If this is not done, voltage drops can occur in the line.

This can lead to significant measurement errors. The effect is particularly relevant at higher currents. Even a line resistance of a few ohms can falsify the actual electrode potential.

Therefore, it should be checked whether the working electrode is correctly connected and whether current conduction and potential measurement are cleanly separated up to the appropriate connection point.

Practical Check: Proper Grounding in Electrochemical Measurement

Before sensitive measurements, the setup should be briefly checked.

Bad: a ring ground is produced along the dashed line

Good: The external device has an (ungrounded) plastic housing

Good: The grounding bridge is only used on one device.

Important questions are:

Is the cell located away from power lines and transformers?
Are measurement lines routed separately from power cables?
Are metal parts near the cell grounded?
Are there any potential ground loops?
Is the shielding correctly connected?
Is the reference electrode shielding not being misused?
Is the cell cable as short as possible?
Is the working electrode wired correctly?
Are there magnetic stirrers or other sources of interference in direct proximity?
Is additional shielding required for small currents?

Stable measurements through controlled grounding

Proper grounding is an important component of electrochemical measurement quality. Clean grounding, short cable runs, and appropriate shielding help to avoid mains hum, ground loops, and electromagnetic interference.

Especially with small currents, high-impedance reference electrodes, or interference-prone laboratory environments, the measurement setup should be consciously planned. This results in more stable measurement signals and better reproducible results.

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