Amprobe GP-1 Earth-Tester-Ground-Probe - Manual (Page 13)

BLUE
RED
GREEN
BLACK
P1
C1 P2 C2
52% 62% 100% 72%
Electrode Resistance:
Test C & D
(cont’d.)
13)Remove P2 (RED) from the 52% rod and clip to the 72% rod.
14)Press and release the START button.
15)Note the value of Rg, or press the SAVE button.The value of Rg will be saved to the next
available memory location. Note the memory location.
16)The electrode resistance is equal to point P2 @62%. Points P2 @52% and P2 @72%
are used to confirm the accuracy of the measurements.
The rule of 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%).
Page 13
Formula 2
To compute differences use following Formula 2:
(P2 @62%) - (P2 @52%) x 100% < ± 10%
(P2 @62%)
(P2 @72%) - (P2 @62%) x 100% < ± 10%
(P2 @62%)