General Tools and Instruments CA10 - Manual (Page 10)

The table below the figure shows the normal measurement result for each of
the four parameters. It also lists possible causes of, and remedies for, abnormal
results.
10
Parameter
Impedance of
live and neutral
conductors
(Z-L and Z-N)
Impedance of
ground
conductor (Z-E)
Normal
Measurement
Result
<0.15
Ω/m for
14AWG conductor
<0.1
Ω/m for
12AWG conductor
<0.03
Ω/m for
10AWG line
<1
Ω for personnel
safety
<0.25
Ω for
equipment safety
Actual Result
Impedance is too
high
Impedance is
too high
Possible Cause
of Abnormal
Result
Circuit is overloaded
Conductor is too thin
for circuit length
and/or circuit’s
current rating
High impedance
point(s) in circuit or
breaker box
Conductor is too thin
for circuit length
and/or circuit’s
current rating
High impedance
point(s) in circuit or
breaker box
Remedy
Redistribute circuit load
Replace wiring with
heavier-gauge conductors
suitable for circuit’s rating
Visually inspect all
connection points to detect
or rule out loose
connections and defective
outlets. If none are
apparent, locate points of
high impedance using an
infrared thermometer (IRT)
to detect their heat, or a
voltmeter to detect
excessive voltage drops
across parts. Repair or
replace defective
wiring/parts.
Replace wiring with
heavier-gauge conductors
suitable for circuit’s
rating
Visually inspect all
connection points to detect
or rule out loose
connections and defective
outlets. If none are
apparent, locate points of
high impedance using an
infrared thermometer (IRT)
to detect their heat, or a
voltmeter to detect
excessive voltage drops
across parts. Alternatively,
run the Z-L and Z-N
impedance tests on the
hot and neutral conductors;
if one conductor produces
a much higher reading
than the other, it is
defective. Repair or
replace defective
wiring/parts.