PGT-61-164 SureTest Circuit Analyzer
6
Voltage Measurements
The line voltage measurement should be 120 VAC +/-10% fluctuation at 60 Hz. The peak
voltage should be 1.414 times the rms line voltage reading for a clean sine waveform. Ground-
to-neutral voltage should be less than 2 VAC. In a single-phase circuit, a higher ground-neutral
voltage indicates excessive current leakage between the neutral and ground conductors. In a 3-
phase circuit with a shared neutral, a high ground-neutral voltage could indicate an unbalanced
load between the three phases or harmonic distortion on the shared neutral. Excessive ground-
neutral voltage may result in inconsistent or intermittent equipment performance.
Troubleshooting Tips for Voltage Issues
Measurement
Expected
Result
Problem Possible
Causes
Possible
Solutions
Too much load on
the load on circuit
Redistribute loads
on the circuit
High Resistance
connection within the
circuit or at the panel
Locate high
resistance
connection/ device
and repair/replace
Line Voltage
120 VAC
220 VAC
108-132 VAC
198-242 VAC
High/low
Supply voltage too
high/low
Consult Power
company
Current leaking from
neutral to ground
Idenify source of
leakage; multiple
bonding points,
equipment or
devices
Unbalanced 3-phase
system
Check load
balance and
redistribute load
Neutral-Ground
Voltage
< 2 VAC
Voltage
High G-N
>2 VAC
Triplen harmonics
returning on neutral
in 3-phase system
Oversize neutral to
impedance.
Reduce harmonic
effect via filter or
other methods
Supply voltage
Too high/low
Consult power
company
Peak Voltage
120 VAC
220 VAC
153-185 VAC
280-342 VAC
High/Low
Peak voltage
High Peak Loads on
line caused by
electronic equipment
on line
Evaluate number
of electronic
devices on circuit
and redistribute if
necessary
Frequency 60
HZ High/Low
Frequency
Supply frequency
Too high/low
Consult power
Company
WARNING!
Do not exceed the unit’s maximum voltage rating of 250VAC!