12
Common AC Voltage Measurements
6.1 Wall Receptacles
If the receptacle is controlled by a switch, make sure the
switch is ON. Set the function/range switch to 250 ACV.
Touch the test leads to the “hot” and “neutral” slots of the
receptacle (see fig. 5.) The needle indicator should read 120
VAC on the 0-250 scale. To test for proper grounding of the
receptacle, touch one test lead to the “hot” (narrow) side of
the receptacle, and the other test lead to the ground slot.
The tester should read 120 VAC as before. To test for proper
grounding of non- polarized receptacles (fig.6), alternately
touch the test leads between the receptacle slots and the
wall plate screw. The tester should indicate 120 VAC when
one test lead contacts the “hot” side of the receptacle. If
ground contact cannot be made on the wall plate screw,
remove the wall plate and touch the electrical box with the
test lead in the same manner as before. The tester should
read 120 VAC with one test lead touching the electrical box
and the other touching the live side of the receptacle. If not,
the receptacle is not properly grounded.
11
1 ) Fully seat the test leads in the correct input jacks.
2) Set the function/range switch to the appropriate AC
voltage range. If the voltage is unknown, use the highest
range. If the voltage applied falls within the range of a
lower setting, reset the function/range switch to the
appropriate setting for greatest accuracy of reading.
3) Touch the test leads to the circuit under test. With AC
voltage, the polarity of the test leads is not a factor.
Use the following chart below as a guide to reading AC
voltage measurements:
ACV
Read
and
Range
Following
Multiply
Setting
Scale
Reading By:
10
0-10
1
50
0-50
1
250
0-250
1
1000
0-10
100
6.0 AC Voltage Measurement
GMT-19A
OHMS ADJUST
1000V DC/A
C
500mA DC
MAX
O
H
M
S
1000
250
50
10
2.5
500m
50m
5m
1000
250
50
10
1.5V
AA
9V
X1K
X10
X1
DC10A
A
C
V
D
C
V
D
C
A
+
–
DC10A
V.
Ω
.A.
COM
20K
Ω
/V DC
8K
Ω
/V AC
1K
100
200
50
500
2K
0
0
0
AC
DC
50
100
150
200
250
10
20
30
40
2
4
6
8
50
10
AC
dB
DC
dB
BA
T
20
10
0
Ω
Ω
BA
T
G O O D
?
-8
0
+6
+12
+16 +18
+20
+22
∞
R E
P L
A C E
5K
10 K
+14
OH
MS
OHMS
GMT-19A
OHMS ADJU
ST
1000V DC/A
C
500mA DC
MAX
O
H
M
S
1000
250
50
10
2.5
500m
50m
5m
1000
250
50
10
1.5V
AA
9V
X1K
X10
X1
DC10A
A
C
V
D
C
V
D
C
A
+
–
DC10A
V.
Ω
.A.
COM
20K
Ω
/V DC
8K
Ω
/V AC
1K
100
200
50
500
2K
0
0
0
AC
DC
50
100
150
200
250
10
20
30
40
2
4
6
8
50
10
AC
dB
DC
dB
BAT
20
10
0
Ω
Ω
BA
T
G O O D
?
-8
0
+6
+12
+16 +18
+20
+22
∞
R E
P L
A C E
5K
10 K
+14
OH
MS
OHMS
5A
5B
Figure 5
Figure 6
AC Scale
in Red
(Use black
numbers on
top for scale.)
AC Voltage
Settings
Red
Black
Neutral
Hot
Ground
10 Amp
Scale
Black
Red
