Extech
Instruments
15 GX900-EU-EN V1.6 4/14
AC
VOLTAGE
MEASUREMENTS
WARNING:
Risk
of
Electrocution.
The
probe
tips
may
not
be
long
enough
to
contact
the
live
parts
inside
some
240V
outlets
for
appliances
because
the
contacts
are
recessed
deep
in
the
outlets.
As
a
result,
the
reading
may
show
0
volts
when
the
outlet
actually
has
voltage
on
it.
Make
sure
the
probe
tips
are
touching
the
metal
contacts
inside
the
outlet
before
assuming
that
no
voltage
is
present.
CAUTION:
Do
not
measure
AC
voltages
if
a
motor
on
the
circuit
is
being
switched
ON
or
OFF.
Large
voltage
surges
may
occur
that
can
damage
the
meter.
1.
Set
the
function
switch
to
the
V~
position.
2.
Insert
the
black
test
lead
banana
plug
into
the
negative
COM
jack.
Insert
red
test
lead
banana
plug
into
the
positive
V
jack.
3.
Touch
the
black
test
probe
tip
to
the
neutral
side
of
the
circuit.
Touch
the
red
test
probe
tip
to
the
“hot”
side
of
the
circuit.
4.
Read
the
voltage
in
the
display.
dBm/dBV
AC
MEASUREMENTS
The
meter
is
capable
of
displaying
AC
voltage
as
a
dB
value;
relative
to
1
milli
‐
watt
(dBm),
relative
to
1V
(dBV),
or
to
a
custom
reference
value.
1.
Set
the
function
switch
to
the
V~
position
2.
Press
the
F1
key
(MENU)
on
the
LCD
and
then
navigate
to
the
dBm/dBV
field
using
the
arrow
keys
and
then
press
OK.
3.
Navigate
to
the
menu
item
labeled
dBm
and
then
press
OK.
4.
Insert
the
black
test
lead
banana
plug
into
the
negative
COM
jack.
Insert
red
test
lead
banana
plug
into
the
positive
V
jack.
5.
Touch
the
black
test
probe
tip
to
the
neutral
side
of
the
circuit.
Touch
the
red
test
probe
tip
to
the
“hot”
side
of
the
circuit.
6.
Read
the
dBm
in
the
primary
display
area
and
read
the
Voltage
in
the
secondary
display
area.
