Amprobe GROUND PROBE GP-1 Manual del usuario - Página 10

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Electrode or Grid System

Resistance:Test C & D

Warning: The power must be turned OFF, the electrode

must be isolated from the utility ground, building steel, or any

other ground, in order for the GP-1 to correctly measure the

resistance value of an earth ground electrode (Test C).

Before isolating the electrode under test, verify that power is

OFF by:

• Measuring the voltage from the grounding conductor to a

reliable earth ground. Use the voltmeter measurement

feature on the GP-1 (see page 14).

• Measuring the leakage current through the electrode using

an AMPROBE Model DLC-100, or equivalent, Digital

Leakage Current Clamp.

Warning: If more than 50ma of current is flowing through

the electrode, do not isolate the ground electrode until the

source of current is located and turned OFF.

The following instructions outline the typical approach to perform a test using the "fall of

potential" or 62% method.

1) Switch the GP-1 to Test C "Earth Resistance"

2) Noting color codes, connect the four test cables to the input jacks of the instrument.

3) Connect the BLACK (C1) and GREEN (P1) test cables to the isolated electrode under

test.

4) To determine the distances from the electrode in which to drive the tet rods, use the

formula on Page 11.

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