Strain Relief and Strain Mitigation: Simple Practices That Reduce Lost Data

Portable data loggers are often used with long sensor leads — thermistor probes, thermocouples, RTDs, or transducers — that run across rooms, into chambers, through ducts, or out windows. In these temporary setups, it’s common for cables to be brushed against, shifted slightly, or adjusted during installation.

Those brief, incidental movements may seem harmless, but they are one of the most common reasons wiring connections come loose in portable data logging applications.

Most of the time, nothing looks wrong at the logger itself. The unit continues running — but a disturbed terminal connection can quietly stop data from being recorded on one or more channels.

This article looks at why that happens, and how simple mechanical practices can significantly reduce the risk.

Why Terminal Connections Are Vulnerable

Terminal blocks are designed to make electrical connections — not to act as load-bearing anchors. When a probe wire is pulled, even slightly, the force is transmitted directly to the termination point. Over time, this can lead to:

• loosened screws

• broken conductor strands

• intermittent contact

• or complete disconnection

In many applications, especially portable or temporary setups, probe cables are exposed to handling, vibration, or incidental pulls. With long sensor leads, a small movement far from the logger can translate into a surprisingly large force at the connector. Managing those forces is just as important as making a good electrical connection.

A Simple Tug-of-War Analogy

One way to visualize strain relief is with a tug-of-war, where two sides pull on a rope trying to pull the other side toward them.

No strain relief

In the first case, two teams pull directly against each other with nothing in between.

Result:
All the force is transmitted directly through the rope. There is no protection at the connection point.

(This is analogous to probe wires connected directly to a terminal block with no slack or strain management.)

Full strain relief (anchored)

In the second case, the rope is wrapped around a solid tree in the middle.

Result:
The tree absorbs the force. Little to no tension reaches the far end of the rope.

(This represents true strain relief — the cable is anchored to a fixed structure, and pulling forces are redirected away from the terminal entirely.)

Strain mitigation (partial protection)

In the third case, the rope is bent around a portion of the tree, but not wrapped or anchored.

Result:
Some force is redirected and absorbed by the tree through friction and a change in direction, but the force is not eliminated. A strong pull still carries through.

(This represents strain mitigation — force is reduced and managed, but not fully removed.)

This third case is where many real-world data-logging installations live.

Strain Relief vs. Strain Mitigation

In fixed installations, strain relief typically means anchoring a cable so that pulling forces are transferred to a rigid structure rather than to the electrical connection itself. In these cases, the goal is to eliminate mechanical load at the terminal entirely.

In many real-world data logging applications, however, anchoring a cable to a panel or structure is not practical or even possible. Probes may be portable, reconfigured frequently, or routed to different locations. In these situations, the goal often shifts from absolute strain relief to strain mitigation.

Strain mitigation focuses on reducing how much force reaches the terminal connection by:

• gripping a cable jacket or bundled section rather than individual conductors,

• distributing load over a larger area,

• introducing slack so small movements are absorbed before reaching the terminals, and

• encouraging clean failure modes (such as a connector disengaging) instead of intermittent electrical contact.

Strain mitigation does not guarantee protection under all possible forces. However, it can dramatically reduce the likelihood of lost data caused by everyday handling, vibration, or incidental pulls — which are the most common causes of field failures.

The diagrams above illustrate this distinction: direct pulling transmits all force, anchoring eliminates it, and intermediate techniques reduce and redirect it. Most portable logging applications fall into this intermediate strain-mitigation category, where thoughtful strain mitigation significantly improves reliability even without a fixed anchor point.

Practical Techniques That Help

Leave slack at the terminal

If you are using a strain relief enclosure, a small service loop or bend inside the enclosure prevents the terminal screw from acting as a mechanical stop. Even modest slack can absorb micro-movement and reduce fatigue at the connection point.

Avoid loading individual conductors

Whenever possible, strain-relief devices should act on a jacketed cable or bundled section, not on individual wires. Pulling on single conductors is the fastest way to create intermittent failures.

Bundling and cinching for flexible setups

When multiple probe cables enter a logger and anchoring is not practical, bundling those cables together for the last several inches near the logger can significantly reduce strain. Expandable sleeving, cinching straps, or similar methods can help the probes behave as a group near the entry point while still allowing reconfiguration.

These approaches provide mitigation rather than absolute relief, but they are often appropriate for portable or frequently reconfigured systems.

Good, Better, Best: A Practical Perspective

Good (basic mitigation):

• Wires are not taut at the terminal

• A small slack loop or bend is provided

• Individual conductors are not supporting cable weight

Better (recommended in most portable installations):

• Strain relief or clamps grip a jacketed or bundled section

• Multiple probe leads are bundled for the last 150–250 mm (6–10 in) near the logger

• Slack is maintained between the clamp and the terminal block

Best (high-stress or permanent environments):

• Cable forces are absorbed by an upstream anchor point

• The logger’s strain relief handles only local movement and vibration

The Takeaway

Not every application allows for perfect strain relief, and that’s okay. The key is understanding how forces travel and making intentional choices to manage them.

Whether through anchoring, bundling, slack, or simple awareness, reducing mechanical stress at the terminal block can go a long way toward improving reliability and preventing lost data.

• Strain relief eliminates force.
• Strain mitigation reduces it.

Both have a place — and knowing the difference helps you choose the right approach for your application.

At ACR Systems, we design and support data loggers for real-world use — including portable and temporary installations where wiring reliability matters just as much as measurement accuracy.