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Measurement Precautions and Tips
Inuence of earth voltage
Due to the presence of leakage current from electrical equipment
connected to the earthing body or of earth current, a voltage may
exist at the earthing body.
If the voltage is less than about 10 V, it will normally not affect the
earth resistance measurement; however, if the earth voltage is
distorted, it may cause measurement errors even at lower voltage
levels below 10 V. For this reason, if an earth voltage of more than
about 5 V is detected, another electrical equipment should be
turned off or the equipment should be disconnected to eliminate the
inuence of earth voltage on the measurement.
During simplied measurement, harmonic leakage current in the
ground line can cause the galvanometer to uctuate. In such a
case, switch the Hz selector from 575 to 600, allowing stable
measurement.
If earth voltage is high, the insulation of the electrical path or
electrical equipment may have deteriorated. Check the insulation
and perform a leakage current test.
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