July 9, 2025
Your load cell cable isn’t just some wire connecting Point A to Point B. It’s part of your measurement system and treating it like any old extension cord is a sure way to mess up your readings. Get the cable wrong and your scale might as well be throwing darts at a board.
Most folks don’t think much about load cell cables until something goes wrong. Then they’re scratching their heads wondering why their readings are off, or why changing cable length suddenly made their calibration worthless.
But the truth is, that cable carries signals so small they make a whisper look loud. Meaning the effect the cable has on your load cells’ outputs is huge. So picking the right one for your application’s needs is actually incredibly important.
What is a Load Cell Cable?
A load cell cable isn’t just a regular wire. It’s designed to handle the tiny electrical signals load cells produce, measured in millivolts, not the volts your household appliances use.
The red and black wires send power to the load cell, the green and white wires bring the signal from the load cell to the indicator.
These cables have shielding to protect against electrical noise, twisted pairs to reduce noise and wire gauges chosen for their resistance properties.
Insulation is important too. If moisture gets in, it can mess with your signal faster than you can say “recalibration”.
Most load cell cables use standard color-coding: red and black for power, green and white for the signal. Some manufacturers may mix it up, but the function is the same: power in, signal out.
What is the Difference Between a 4-wire and a 6-wire Load Cell?
Standard 4-wire load cell cable works fine for most applications but has limitations that’ll bite you if you’re not careful. 4-wire load cells are calibrated to the cable length and cutting the cable will negatively affect the accuracy of the load cell. Change the length and you’ve changed the resistance. Change the resistance and your readings go sideways.
The 4-wire setup uses two wires for excitation and two for signal. Simple, straightforward and cheap. But it’s also sensitive to cable length, temperature changes and anything else that affects wire resistance. A major drawback of 4-wire load cells is their sensitivity to cable length. Changes in cable length can alter the resistance leading to inaccurate measurements.
6-wire cables add two “sense” wires that monitor what’s actually happening at the load cell end. The 6-wire load cells have two extra wires called “reference” (Sense + and Sense –) that are used to measure and adjust the actual voltage reaching the load cells. These sense wires let the system compensate for voltage drops caused by long cables, temperature changes or electrical interference.
The sense wires essentially tell your indicator, “Here’s what the load cell is actually seeing” instead of assuming it’s getting what you sent. This feedback loop allows the system to adjust and maintain accuracy even when conditions aren’t perfect.
How Long Can Load Cell Wires Be?
Cable length limits depend on your setup but there are some general rules. The suggested maximum run of 4 cores is shorter than the 6-wire systems.
6-wire load cells offer enhanced compensation for lead resistance effects and allow for longer cable lengths without causing significant signal degradation. Some installations run hundreds of meters.
The math gets complicated, but here’s the breakdown:
Maximum cable length = Allowable cable resistance ÷ Cable resistance per meter ÷ Number of load cells
Wire gauge matters too. Thicker wire has lower resistance per foot, allowing you to run longer distances.
Temperature affects everything. Hot weather increases resistance, cold weather decreases it. Cable resistance is a function of temperature. A temperature change on a load cell or a series of load cell cables affects the thermal characteristics. What worked fine in winter might read differently come summer if you don’t account for these changes.
When Cable Length Becomes a Problem
You’ll know you’ve got cable length problems when your readings start wandering or when identical loads give different measurements.
The longer your cable, the more voltage gets lost along the way. Your load cell thinks it’s getting 10 volts for excitation but it’s really only seeing 9.8 volts. Since output is proportional to excitation voltage, your readings will be proportionally low.
Temperature makes this worse. It’s important that the cable resistance be the same for all load cells, including load cells in a series. If you’ve got multiple load cells with different cable lengths, temperature changes will affect them differently and throw off your system balance.
Compensating for Cable Issues
The best compensation is using 6-wire cable from the start. To eliminate the errors associated with a 4-wire system requires a 6-wire cable, which is run to the end of the load cell cable or connector and is used with an indicator that has sense lead capability. The sense lines monitor what’s actually happening at the load cell and adjust accordingly.
If you’re stuck with 4-wire cable, keep runs short and use the thickest wire gauge practical for your application. Match cable lengths when using multiple load cells, different lengths mean different resistances which means measurement errors.
Proper installation helps too. Use the shield wire and ground properly and keep load cell cables away from power lines. Electrical interference can make even short cable runs act up.
Temperature compensation in 4-wire systems usually means recalibrating for different seasons or using indicators with built-in temperature correction. It’s not perfect but it’s better than ignoring the problem.
Making the Right Choice For Your Specific Needs
For short runs in controlled environments, 4-wire cable works fine and costs less.
4-Wire Load Cells
Ideal for standard applications with stable environments, short cable lengths and where cost is a key factor. Think bench scales, small platform scales or anything where the cable runs less than 15 feet.
For longer runs, harsh environments or precision applications, 6-wire cable is worth the extra cost.
6-Wire Load Cells
Best suited for high-accuracy applications, environments subject to temperature fluctuations or where long cable lengths are necessary. The sense wires eliminate most cable-related errors.
Don’t cheap out on cable quality. Load cell signals should not be conducted with an ordinary instrument cable. Instead it should be conducted with a dedicated load cell cable. The resistance needs to be as low as possible and the shielding needs to keep interference out. To dive deeper into load cell wiring and configurations, read our blog A Comprehensive Guide to Load Cell Wiring -Massload Technologies Inc.
Choose the Right Load Cell Cable with Help from Massload
Load cell cable is more important than most people think. It’s not just connecting wires, it’s part of your measurement system. Get it wrong and your readings will be wrong. Get it right and your system will give you accurate measurements for years to come.
Respect the limits, match your cable to your application and don’t try to save a few bucks on something that affects every measurement you make. Your future self will thank you when your scales keep working and not driving you nuts with inconsistent readings.
Need help choosing the right cable or load cell? Reach out to the experts at Massload today for guidance and weighing solutions tailored to your needs.
