11
3.9 Interference (Phantom) Voltage
It is possible for wiring that is ‘dead’ to
indicate the apparent presence of voltage at
power frequency.
If wiring that is live is running in close
proximity to the ‘dead’ wiring being tested,
there can be capacitive or inductive
coupling between the two, thereby causing
interference (phantom) voltage.
Refer to section 1.3 for safety advice
relevant to interference voltage.
3.10 Single Pole Phase Test
Warning
Single pole phase testing is not suitable to
determine if a circuit is not hazardous live.
A double pole voltage test should always be
used for that purpose.
While taking all required safety precautions
connect the positive test probe
2
to the
UUT (Unit or location under test).
The phase indicator LED
9
will illuminate
and the buzzer will sound if the presence of
AC voltage >100V is detected.
3.11 Phase Rotation Test
While taking all required safety precautions
connect the test probes L1 and L2 to the
phases to be tested.
The phase to phase voltage will be indicated
by the voltage threshold LED’s
12
or for the
VT28 also by the LCD
4
.
The direction of the phase rotation will be
indicated by one of the green phase rotation
LED’s
11
marked L (left rotation) and R
(right rotation).
Note: The method of phase sequence
detection relies on capacitive coupling to
earth through the user. If the insulation/
grounding conditions of the installation under
test or user are not satisfactory then the test
results may be impaired.
3.12 Testing for Continuity
While taking all required safety precautions
firmly connect both test prods to the UUT
(Unit or location under test).
