load cell wiring

A 4-wire circuit carries excitation voltage to the bridge and brings back the signal, but it can’t compensate for resistance in the cable itself. On long runs that resistance drops a bit of the excitation, shifting the sensitivity. A 6-wire cable adds two sense wires that measure the voltage right at the load cell. The readout then adjusts the supply to keep the excitation stable, so you get more accurate readings regardless of cable length or temperature swings. For most geotechnical installations with cables over 30 meters, we recommend six-wire connections.

Noise often sneaks in from variable-frequency drives, radios, or nearby power lines. The built-in braided shield inside Kingmach cables does most of the work if you handle it properly. Connect the shield to the data logger’s ground terminal at one end only—usually the instrument end—and leave the other end floating. Avoid routing signal cables in the same conduit as AC power. If noise persists, a ferrite bead clamped around the cable near the logger can help. For extreme cases, we can supply sensors with additional internal filtering.

Yes, cables can be extended, but it changes the bridge resistance and sensitivity slightly. For a simple splice, use a shielded junction box and solder connections to keep signal integrity. Then recalibrate the system as a whole—hang known weights or apply a reference force at the sensor to check the output. Kingmach often provides factory-fitted longer cables or field connectors that don’t require recalibration, since we match the impedance during production. If you’re unsure, send us the cable specs and we’ll calculate the expected shift.

Drift can come from moisture in connectors, a compromised shield, or even a damaged strain gauge. First, inspect all wiring junctions for corrosion or loose crimps. Measure the excitation voltage at the load cell end: if it’s unstable, check the power supply and cable continuity. For our sensors, typical zero drift is below 0.1% FS per year under normal field conditions, so a sudden drift usually points to a physical fault in the wiring or water ingress. We have a troubleshooting guide that steps through insulation resistance checks and signal isolation tests.

Every sensor we ship includes a printed wiring sheet with color codes and pinouts, and you can download the latest versions from our website. For custom configurations—like dual-bridge setups, built-in amplifiers, or mixed RS485/analog output—our engineers prepare a project-specific wiring document. Just tell us the sensor model and the readout equipment you’re using, and we’ll send a connection drawing. If field support is needed, our regional distributors often have experienced techs who can visit your site and verify the setup.