Extech Instruments 411 User manual

User's Guide
True RMS Multimeter
Extech 411

V4.0 5/072
Introduction
Congratulations on your purchase of the Extech 411 (part number
EX411) True RMS Multimeter. This meter measures AC/DC
Voltage, AC/DC Current, Resistance, Diode Test, and Continuity
plus Thermocouple Temperature. Proper use and care of this
meter will provide many years of reliable service.
Safety
This symbol adjacent to another symbol,
terminal or operating device indicates that the
operator must refer to an explanation in the
Operating Instructions to avoid personal injury
or damage to the meter.
This WARNING symbol indicates a potentially
hazardous situation, which if not avoided,
could result in death or serious injury.
This CAUTION symbol indicates a potentially
hazardous situation, which if not avoided, may
result damage to the product.
This symbol advises the user that the
terminal(s) so marked must not be connected
to a circuit point at which the voltage with
respect to earth ground exceeds (in this case)
1000 VAC or VDC.
This symbol adjacent to one or more terminals
identifies them as being associated with
ranges that may, in normal use, be subjected
to particularly hazardous voltages. For
maximum safety, the meter and its test leads
should not be handled when these terminals
are energized.
This symbol indicates that a device is
protected throughout by double insulation or
reinforced insulation.
WARNING
CAUTION
MAX
1000V

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OVERVOLTAGE CATEGORY III
This meter meets the IEC 610-1-95 standard for
OVERVOLTAGE CATEGORY III. Cat III meters are protected
against overvoltage transients in fixed installation at the
distribution level. Examples include switches in the fixed
installation and some equipment for industrial use with
permanent connection to the fixed installation.
SAFETY INSTRUCTIONS
This meter has been designed for safe use, but must be
operated with caution. The rules listed below must be carefully
followed for safe operation.
1. NEVER apply voltage or current to the meter that exceeds the
specified maximum:
Input Protection Limits
Function Maximum Input
VAC 750V DC/AC
V DC or V AC 1000V DC/AC, 200Vrms on 200mV range
mA DC 200mA 250V fast acting fuse
A DC 20A 250V fast acting fuse(30 seconds max
every 15 minutes)
Ohms, Continuity 250Vrms for 15sec max
2. USE EXTREME CAUTION when working with high voltages.
3. DO NOT measure voltage if the voltage on the "COM" input
jack exceeds 1000V above earth ground.
4. NEVER connect the meter leads across a voltage source
while the function switch is in the current, resistance, or diode
mode. Doing so can damage the meter.
5. ALWAYS discharge filter capacitors in power supplies and
disconnect the power when making resistance or diode tests.
6. ALWAYS turn off the power and disconnect the test leads
before opening the covers to replace the fuse or battery.
7. NEVER operate the meter unless the back cover and the
battery cover is in place and fastened securely.

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Controls and Jacks
1. Rubber holster
2. 2000 count LCD display
3. Degrees F button
4. Degrees C button
5. Function switch
6. mA, uA and A input jacks
7. COM input jack
8. Positive input jack
9. Battery check button
10. Hold button
11. Backlight button
Note: Tilt stand and battery compartment are on rear of unit.
Symbols and Annunciators
•))) Continuity
Diode test
Battery status
Test lead connection
error
µ micro (10-6) (amps)
m milli (10-3) (volts, amps)
k kilo (103) (ohms)
M mega (106) (ohms) Ω Ohms
A Amps V Volts
AC Alternating current AUTO Autoranging
DC Direct current HOLD Display hold
ºF Degrees Fahrenheit ºC Degrees Centigrade

V4.0 5/075
Specifications
Function Range
Resolution Accuracy
200mV 0.1mV ±(0.3% reading + 2 digits)
2V 0.001V
200V 0.1V ±(0.5% reading + 2 digits)
DC Voltage
(V DC)
1000V 1V ±(0.8% reading + 2 digits)
50 to 400Hz 400Hz to 1kHz
2V 0.001V
±(1.0% reading
+6 digits
±(2.0% reading
+ 8 digits
200V 0.1V ±(1.5% reading
+6 digits
±(2.5% reading
+8 digits
AC Voltage
(V AC)
(True rms)
750V 1V ±(2.0% reading
+6 digits
±(3.0% reading
+8 digits
200µA 0.1µA
200mA 0.1mA ±(1.5% reading + 3 digits)
DC Current
(A DC)
20A 0.01A
±(2.5% reading + 3 digits)
50 to 400Hz 400Hz to 1kHz
200mA 0.1mA ±(1.8% reading
+8 digits
±(2.5% reading
+10 digits)
AC Current
(A AC)
(True rms)
20A 0.01A
±(3.0% reading
+8 digits)
±(3.5% reading
+10 digits)
200Ω0.1Ω±(0.8% reading +4 digits)
2000Ω1Ω±(0.8% reading +2 digits)
20kΩ0.01kΩ
200kΩ0.1kΩ±(1.0% reading +2 digits)
Resistance
20MΩ0.01MΩ±(2.0% reading +5 digits)
-4 to
1382ºF
1ºFTemperature
-20 to
750ºC
1ºC
±(3.0% reading +3 digits)
(meter only, probe accuracy not
included)
NOTE: Accuracy specifications consist of two elements:
•(% reading) – This is the accuracy of the measurement circuit.
•(+ digits) – This is the accuracy of the analog to digital converter.
NOTE: Accuracy is stated at 65oF to 83oF (18oC to 28oC) and less
than 75% RH.

V4.0 5/076
Specifications
Diode Test Test current of 1mA maximum, open
circuit voltage 2.8V DC typical
Continuity Check Audible signal will sound if the
resistance is less than approximately
150Ω
Input Impedance 10MΩ
AC Response True rms
ACV Bandwidth 50Hz to 1kHz
DCA voltage drop 200mV
Display 3 ½ digit, 2000 count LCD, 0.9” digits
Auto-Power Off 15 minutes (approximately)
Overrange indication “1” is displayed
Polarity Automatic (no indication for positive
polarity); Minus (-) sign for negative
polarity.
Measurement Rate 2 times per second, nominal
Low Battery Indication “ ” is displayed if battery voltage
drops below operating voltage
Battery One 9 volt (NEDA 1604) battery
Fuses mA, µA ranges; 0.2A/250V fast blow
A range; 20A/250V ceramic fast blow
Operating Temperature 41ºF to 104ºF (5ºC to 40ºC)
Storage Temperature -4oF to 140oF (-20oC to 60oC)
Operating Humidity Max 80% up to 87ºF (31ºC)
decreasing linearly to 50% at
104ºF(40ºC)
Storage Humidity <80%
Operating Altitude 7000ft. (2000meters) maximum.
Weight 0.753lb (342g) (includes holster).
Size 7.36” x 3.2” x 2.0” (187 x 81 x 50mm)
(includes holster)
Safety For indoor use and in accordance with
the requirements for double insulation to
IEC1010-1 (1995): EN61010-1 (1995)
Overvoltage Category III 600V and
Category II 1000V, Pollution Degree 2.

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Operating Instructions
WARNING: Risk of electrocution. High-voltage circuits, both AC
and DC, are very dangerous and should be measured with great
care.
1. ALWAYS turn the function switch to the OFF position when the
meter is not in use.
2. If “1 ” appears in the display during a measurement, the value
exceeds the range you have selected. Change to a higher range.
NOTE: On some low AC and DC voltage ranges, with the test
leads not connected to a device, the display may show a random,
changing reading. This is normal and is caused by the high-input
sensitivity. The reading will stabilize and give a proper
measurement when connected to a circuit.
DC VOLTAGE MEASUREMENTS
CAUTION: Do not measure DC 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
highest V DC ( ) position.
2. Insert the black test lead banana
plug into the negative COM jack.
Insert the red test lead banana
plug into the positive Vjack.
3. Touch the black test probe tip to
the negative side of the circuit.
Touch the red test probe tip to the
positive side of the circuit.
4. Read the voltage in the display.
Reset the function switch to
successively lower V DC
positions to obtain a higher
resolution reading. If the polarity
is reversed, the display will show
(-) minus before the value.

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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 highest
V AC ( ) position.
2. Insert the black test lead banana
plug into the negative COM jack.
Insert red test lead banana plug into
the positive Vjack.
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.
Reset the function switch to
successively lower V AC positions to
obtain a higher resolution reading.

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DC CURRENT MEASUREMENTS
CAUTION: Do not make current measurements on the 20A
scale for longer than 30 seconds. Exceeding 30 seconds may
cause damage to the meter and/or the test leads.
1. Insert the black test lead banana plug into the negative COM
jack.
2. For current measurements up to 200µA DC, set the function
switch to the 200µA DC ( )position and insert the red test
lead banana plug into the uA/mA jack.
3. For current measurements up to 200mA DC, set the function
switch to the 200mA DC position and insert the red test lead
banana plug into the uA/(mA jack.
4. For current measurements up
to 20A DC, set the function
switch to the 20A DC range
and insert the red test lead
banana plug into the 20A jack.
5. Remove power from the
circuit under test, then open
up the circuit at the point
where you wish to measure
current.
6. Touch the black test probe tip
to the negative side of the
circuit.
Touch the red test probe tip to
the positive side of the circuit.
7. Apply power to the circuit.
8. Read the current in the
display.

V4.0 5/0710
AC CURRENT MEASUREMENTS
CAUTION: Do not make current measurements on the 20A
scale for longer than 30 seconds. Exceeding 30 seconds may
cause damage to the meter and/or the test leads.
1. Insert the black test lead banana plug into the negative COM
jack.
2. For current measurements up to 200mA AC, set the function
switch to the highest 200mA AC ( ) position and insert the
red test lead banana plug into the mA jack.
3. For current measurements up to 20A AC, set the function
switch to the 20A AC range
and insert the red test lead
banana plug into the 20A
jack.
4. Remove power from the
circuit under test, then open
up the circuit at the point
where you wish to measure
current.
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. Apply power to the circuit.
7. Read the current in the
display.