You're right to be suspicious. Those results are highly irregular and suggest a problem with the test, the setup, or potentially even fabricated data. Here's a breakdown of why, and what you should consider

Why the Results Are Dubious:
Lack of a Characteristic Curve

A proper fall-of-potential test should exhibit a distinct curve. Near the ground rod under test, the soil resistance is high. As you move further away with the test probe, the resistance decreases rapidly until you reach a point where the probe is effectively outside the influence of the ground rod. Beyond that point, the resistance should plateau. The 61.8% or 62% distance method helps find that plateau. Your results, with almost identical readings between 20ft and 80ft, completely lack this characteristic curve.

Extremely Low Resistance

A ground resistance of 1 ohm is generally considered excellent, even in ideal conditions. To have that reading, and consistently for 60 feet, suggests very low soil resistivity and a very effective grounding system. While possible, it's statistically unlikely unless the soil is saturated with conductive salts or you're testing in a highly conductive environment (like a salt marsh). Furthermore, the very slight decline at the end (0.90 ohms) suggests that 1 ohm isn't the true resistance of the grounding electrode, but is rather resistance introduced by the test equipment.

Unrealistic Consistency

Soil is rarely homogeneous. Variations in moisture content, soil composition, and buried objects (like rocks or utilities) will usually cause fluctuations in resistance readings at different distances. The extremely consistent 1.00 ohm readings are highly unlikely.

Implausible Drop-off

The drop from 1.10 ohms to 1.00 ohms at 20 feet is also questionable. You'd expect a more significant drop initially and then a gradual flattening.

Possible Explanations for the Strange Readings (assuming no deliberate fraud)



Bad Connections

Loose, corroded, or improperly made connections in the test circuit can introduce resistance that masks the actual ground resistance.

Insufficient Test Current

A weak test current might not be able to overcome the resistance of the soil, leading to inaccurate readings.

Probe Too Close

The auxiliary current probe might be too close to the ground rod under test or the auxiliary potential probe. The 61.8% method is important!

Probes Aligned

The auxiliary probes may not have been arranged in a straight line with the ground rod.

Incorrect Meter Settings

The meter may have been set to the wrong range or have a faulty auto-ranging function.

Nearby Underground Conductors

Buried metallic objects like pipes, fences, or utility lines can create a parallel path for the test current, skewing the results. This is particularly likely if the probes were placed near these objects.

High Soil Moisture

Very high soil moisture (after heavy rain, for example) can lower soil resistivity, but it wouldn't explain the consistent readings.

Faulty Meter

The meter itself could be malfunctioning.

Improper Probe Depth

Probes should be driven deep enough to make good contact with the soil but not so deep that they contact buried objects.

Unusually Low Soil Resistivity

While unlikely, the soil at the test location could have unusually low resistivity. Investigate the soil composition and moisture content.

What You Should Do

1.

Question the Contractor Directly

Start by asking the contractor about the specific test setup, procedures, and equipment they used. Ask for detailed explanations of any deviations from standard testing practices. Ask them to show you their field notes and calibration records for the test equipment.2.

Witness a Retest

The best approach is to require the contractor to re-perform the test while you (or a qualified representative) are present to observe and verify the procedure. Pay close attention to:

Probe Placement

Ensure proper spacing (use the 61.8% method) and linear alignment.

Connection Quality

Verify that all connections are clean, tight, and properly made.

Meter Settings

Confirm that the meter is set to the correct range and function.

Test Current

Ensure that sufficient test current is being injected into the ground.*

Probe Depth

Observe that the probes are properly inserted into the ground.3.

Independent Verification

If you have persistent doubts, consider hiring a different contractor to perform an independent ground resistance test.4.

Check for Buried Utilities

Before any testing, perform a "one-call" locate to identify any buried utilities in the area. This will help avoid damaging them and can also help explain unusual readings if utilities are near the test area.5.

Examine Soil Conditions

While not always definitive, try to get a sense of the soil composition and moisture content in the area. Is it sandy, clayey, rocky, or saturated?6.

Review Project Specifications

Review the original project specifications to ensure that the test results meet the required ground resistance values.

In Conclusion:

Your skepticism is justified. The reported results are highly unusual and warrant a thorough investigation. A retest, properly witnessed and documented, is the best way to determine the actual ground resistance and the validity of the contractor's claims. Don't accept these results at face value. Flag for review