Amprobe GP-1 Software - Manual (Page 6)

3.7. GP-1 Calculator
The Gp-1 Calculator is a very handy tool to compute distances in between the test rods for Tests A and C-
D. It also checks the accuracy of the measurement for test C-D.
TEST A
To compute the distances between the test rods for test A – Soil Resistivity, click on
Test A.
The screen such as shown on [fig.5] will appear. Follow the instructions on the screen.
•
Select Feet (Inches) or Metric system
• Select the depth you want to drive test rods.
Note: The GP-1 comes with standard 9" test rods and in this case you need to select distances 15’
between the rods. Setup the GP-1 instrument under DIST to 15 feet (refer to the GP-1 user manual)
TEST C-D
To compute the distances between the test rods, or to check the accuracy of the measurement for test C-D
•
Electrode Resistance click on Test C , D.
The screen such as shown on [fig.6] will appear. Follow the instructions on the screen.
The upper part is used to compute the distances between the test rods. Input a depth of the existing
ground rod or diagonal of the grid system in feet and click on Calculate. Setup the ground rods as it is
shown on the drawing.
The lower part of the screen is used to check if the measurement was accurate. The rule of the thumb is
that in order to perform an accurate measurement, the difference in resistances between points marked as
P(62%) and P(52%) as well as between points P(72%) and P(62%) should be less than 10%. Input the
results of the measurement into the respective fields marked as P(52%), P(62%), P(72%). Click on Check
button.
If the difference is lower than 10%, then the resistance of the electrode is equal to resistance of Point
P(62%).
If the difference is higher than 10%, then it is necessary to proportionally increase the distances between
the test rods and retest
4. Technical Support
4.1. Technical support.
For software updates: Web: www.amprobe.com
For Technical assistance, please contact:
1-800-327-5060