Bad Situation #1
The local conductivity will show as a good ground but there is actually
poor ground between the rods and the material being pumped.
Bad Situation #2
The clamps are connected to the pipes, but the pipes may be insulated
(coated) from the ground, through the ground. The PosiGround signal is
not forced to go as it should be to verify ground conductivity.
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672-H Manual