Extech Instruments EX623 User manual

User's Guide
400Amp True RMS AC/DC Clamp Meter
with IR Thermometer
Model EX623

EX623-en-GB_v3.0 4/15
2
Introduction
Congratulations on your purchase of this Extech EX623 True RMS Clamp Meter. This meter measures
AC Current, DC Current, AC/DC Voltage, Resistance, Capacitance, Frequency, Diode Test, Duty
Cycle and Continuity. Special features include Dual Input Thermocouple Temperature, Non-Contact IR
Temperature and Non-Contact Voltage detector. The double molded case is designed for heavy duty
use. This meter is shipped fully tested and calibrated and, with proper use, will provide years of
reliable service.
Safety
International Safety Symbols
This symbol, adjacent to another symbol or terminal, indicates the user must refer
to the manual for further information.
This symbol, adjacent to a terminal, indicates that, under normal use, hazardous
voltages may be present
Double insulation
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.
PER IEC1010 OVERVOLTAGE INSTALLATION CATEGORY
OVERVOLTAGE CATEGORY I
Equipment of OVERVOLTAGE CATEGORY I is equipment for connection to circuits in which
measures are taken to limit the transient overvoltages to an appropriate low level.
Note – Examples include protected electronic circuits.
OVERVOLTAGE CATEGORY II
Equipment of OVERVOLTAGE CATEGORY II is energy-consuming equipment to be supplied from
the fixed installation.
Note – Examples include household, office, and laboratory appliances.
OVERVOLTAGE CATEGORY III
Equipment of OVERVOLTAGE CATEGORY III is equipment in fixed installations.
Note – Examples include switches in the fixed installation and some equipment for industrial use with
permanent connection to the fixed installation.
OVERVOLTAGE CATEGORY IV
Equipment of OVERVOLTAGE CATEGORY IV is for use at the origin of the installation.
Note – Examples include electricity meters and primary over-current protection equipment
WARNING
CAUTION

EX623-en-GB_v3.0 4/15
3
SAFETY NOTES
Do not exceed the maximum allowable input range of any function.
Do not apply voltage to meter when resistance function is selected.
Set the function switch OFF when the meter is not in use.
Remove the battery if meter is to be stored for longer than 60 days.
WARNINGS
Set function switch to the appropriate position before measuring.
When measuring volts do not switch to current/resistance modes.
Do not measure current on a circuit whose voltage exceeds 600V.
When changing ranges always disconnect the test leads from the circuit under test.
CAUTIONS
Improper use of this meter can cause damage, shock, injury or death. Read and understand
this user manual before operating the meter.
Always remove the test leads before replacing the battery or fuses.
Inspect the condition of the test leads and the meter itself for any damage before operating the
meter. Repair or replace any damage before use.
Use great care when making measurements if the voltages are greater than 25VAC rms or
35VDC. These voltages are considered a shock hazard.
Always discharge capacitors and remove power from the device under test before performing
Diode, Resistance or Continuity tests.
Voltage checks on electrical outlets can be difficult and misleading because of the uncertainty
of connection to the recessed electrical contacts. Other means should be used to ensure that
the terminals are not "live".
If the equipment is used in a manner not specified by the manufacturer, the protection provided
by the equipment may be impaired.
This device is not a toy and must not reach children’s hands. It contains hazardous objects as
well as small parts that the children could swallow. In case a child swallows any of them,
please contact a physician immediately
Do not leave batteries and packing material lying around unattended; they can be dangerous
for children if they use them as toys
In case the device is going to be unused for an extended period of time, remove the batteries
to prevent them from draining
Expired or damaged batteries can cause cauterization on contact with the skin. Always,
therefore, use suitable hand gloves in such cases
See that the batteries are not short-circuited. Do not throw batteries into the fire.
Do not directly view or direct the laser pointer at an eye. Low power visible lasers do not
normally present a hazard, but may present some potential for hazard if viewed directly for
extended periods of time
Function Maximum Input
A AC, 400A DC/AC
A DC 400A DC/AC
V DC, V AC 600V DC/AC
Resistance, Capacitance, Frequency, Diode Test 250V DC/AC
A 4000 A
Type K Temperature 30V DC, 24V AC

EX623-en-GB_v3.0 4/15
4
Description
Meter Description
1. Current clamp
2. Clamp opening trigger
3. IR thermometer and Laser Button
4. HOLD/BACKLIGHT button
5. MODE / ZERO button
6. Backlit LCD Display
7. Type K input jacks
8. Multimeter input jacks
9. IR thermometer sensor and Laser pointer (rear)
10. Function switch
11. PEAK button
12. MAX/MIN button
13. Range button
14. Thermocouple display button
15. Battery compartment (rear)
16. Non-Contact Voltage Detector
17. NCV LED indicator
18. Input shutter
Display icons Description
HOLD Data Hold
APO Auto Power Off
AUTO Autoranging
PPeak Hold
DC Direct Current
AC Alternating Current
MAX Max reading
MIN Min reading
Low battery
ZERO DCA or CAP zero
mV or V Milli-volts or Volts (Voltage)
Ohms (Resistance)
A Amperes (Current)
F Farad (Capacitance)
Hz Hertz (Frequency)
% Duty Ratio
oF and oC Fahrenheit and Celsius units (Temperature)
T1, T2, T1-T2Therocouple 1, Thermocouple 2, Thermocouple difference
n, m, , M, k Unit of measure prefixes: nano, milli, micro, mega, and kilo
))) Continuity test
Diode test
Laser pointer

EX623-en-GB_v3.0 4/15
5
Operation
NOTES: Read and understand all Warning and Caution statements in this operation manual prior
to using this meter. Set the function select switch to the OFF position when the meter is not in use.
Input Shutter
The Input Shutter inhibits simultaneous connection to the thermocouple jacks and the DMM input
jacks. This is a safety feature which prevents a potentially hazardous condition from existing during
high voltage measurements. Slide the shutter up for test lead measurements or slide it down for
thermocouple temperature measurements.
Non-Contact Voltage Detector
WARNING: Risk of Electrocution. Before use, always test the Voltage Detector on a known live
circuit to verify proper operation.
1. Rotate the Function switch to any measurement position.
2. Place the detector probe tip on the conductor to be tested.
3. If AC voltage is present, the NCV detector light will turn on
with a steady red light.
NOTE: The conductors in electrical cord sets are often twisted. For
best results, move the probe tip along a length of the cord
to assure placing the tip in close proximity to the live
conductor.
NOTE: The detector is designed with high sensitivity. Static
electricity or other sources of energy may randomly trip the sensor. This is normal operation.

EX623-en-GB_v3.0 4/15
6
AC/DC Current Measurements
WARNING: Disconnect the test leads before making clamp measurements.
1. Rotate the Function switch to the 400AAC/DC
position
2. Press the MODE button to select AC or DC.
3. Press the trigger to open jaw. Fully enclose
only one conductor.
4. Read the current value in the display.
5. If the value is less than 40A, rotate the
function switch to the 40AAC/DC position to
improve resolution.
Polarity
When measuring from front to back of the
EX623 the meter will display a minus (-) sign before the measurement. If the user requires a
positive (+) sign displayed, the meter must be tested from back to front.
DCA Zero
The Zero feature removes offset values and improves accuracy for DC current
measurements. To perform a zero, select ADC and, with no conductor in the jaw, press and hold
the MODE ZERO button for two beeps. The display will zero. The offset value is now stored and
removed from all measurements.
Frequency
When ACV is selected, the measured frequency can be viewed in the lower display.
AC/DC Voltage Measurements
CAUTION: Do not measure voltages if a motor on the circuit is being switched ON or OFF. Large
voltage surges may occur that can damage the meter.
1. Slide the input shutter to the up position.
2. Rotate the function switch to the V position.
3. Press the MODE button to select AC or DC Voltage.
4. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive Vjack.
5. 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.
6. Read the voltage value in the display.
Frequency
When ACA is selected, the measured frequency can be viewed in the
lower display.

EX623-en-GB_v3.0 4/15
7
Resistance Measurements
Note: Remove power from the device under test before making resistance measurements
1. Slide the input shutter to the up position.
2. Set the function switch to the position.
3. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive Vjack.
4. Touch the black test probe tip to one side of the device.
Touch the red test probe tip to the other side of the device.
5. Read the resistance value in the display.
Continuity Test
1. Connect as described for resistance measurements.
2. Press the MODE button to select continuity))).
3. Touch the test probe tips across the circuit or component under test.
4. If the resistance is < 50, a tone will sound.
Diode Test
1. Connect as described for resistance measurements
2. Press the MODE button to select diode test .
3. Touch the test probe tips to the diode or semiconductor junction under test. Note the meter
reading.
4. Reverse the test lead polarity by reversing the red and black leads. Note this reading.
5. The diode or junction can be evaluated as follows:
If one reading displays a value (typically 0.400V to 01.800V) and the other reading
displays OL, the diode is good.
If both readings display OL the device is open.
If both readings are very small or ‘0’, the device is shorted.

EX623-en-GB_v3.0 4/15
8
Capacitance Measurements
WARNING: To avoid electric shock, discharge the capacitor before measuring.
1. Slide the input shutter to the up position.
2. Rotate the function switch to the capacitance position.
3. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive jack.
4. Touch the black test probe tip to one side of the device.
Touch the red test probe tip to the other side of the device.
5. Read the capacitance value in the display.
Note: For very large values of capacitance measurement time can be several
seconds before the final reading stabilizes.
Note: The Zero feature removes stray test lead capacitance to improve the
accuracy of low value capacitance measurements. To perform a zero, Press
and hold the MODE ZERO button for two beeps. The display will zero. The
offset value is now stored and is removed from all measurements.
.
Frequency and Duty Ratio Measurements
1. Slide the input shutter to the up position.
2. Rotate the function switch to the Hz % Position.
3. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive Hz jack.
4. Touch the black test probe tip to one side of the device.
Touch the red test probe tip to the other side of the device.
5. Read the Frequency value on the upper large display.
Read the Duty Ratio on the lower small display.
6. Press the MODE button to display the Duty Ratio on the large
display.

EX623-en-GB_v3.0 4/15
9
A DC/AC Current Measurements
1. Slide the input shutter to the up position.
2. Rotate the function switch to the A position.
3. Press the MODE button to select AC or DC.
4. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive Ajack.
5. Turn power to the circuit under test off and make a break in the circuit.
6. Insert the meter in series with the circuit;
Touch the black test probe tip to the negative side of the break.
Touch the red test probe tip to the positive side of the break.
7. Turn circuit power on.
8. Read the current value in the display.
Type K Temperature Measurements
1. Slide the input shutter to the down position.
2. Rotate the function switch to the TYPE K temperature position.
3. Press the MODE button to select °F or °C.
4. Insert the Temperature Probe(s) into the T1 and/or T2 type k sockets.
5. Place the temperature probe tip(s) where needed.
6. Read the temperature on the display.
7. Press the T1-T2 button to step through the display combinations:
Upper display Lower display
a. T1 T2
b. T2 T1
c. T1-T2 T1
d. T1- T2 T2
Note: In case of an open input or a temperature overrange, the meter will display “- - - -” .

EX623-en-GB_v3.0 4/15
10
Non-Contact InfraRed Temperature Measurements
1. Rotate the function switch to the IR position.
2. Press the MODE button to select °F or °C.
3. Aim the infrared sensor (rear of the meter) at the surface
to be measured.
4. Press the IRT button to turn on the IR thermometer
and laser pointer. The laser pointer identifies the surface
spot to be measured.
5. The area of the surface to be measured must be larger
than the spot size as determined by the distance to spot
size specification.
6. Read the temperature in the large upper display. When
the IRT button is released the displayed temperature will be held for approx. 10 seconds.
7. Read the MAX temperature in the lower display.
Press the MAX/MIN button to toggle the lower display between the maximum and minimum
measured values.
WARNING: Do not directly view or direct the laser pointer at an eye.
Low power visible lasers do not normally present a hazard, but may
present some potential for hazard if viewed directly for extended periods
of time.
IR Spot to Distance Diagram
The 8:1 spot to distance ratio determines the size of
the measured surface area with respect to the
distance the meter is held away from the surface.
IR Measurement Notes
1. The object under test should be larger than the
spot (target) size calculated by the field of view diagram.
2. If the surface of the object under test is covered with frost, oil, grime, etc., clean before taking
measurements.
3. If an object's surface is highly reflective, apply masking tape or flat black paint to the surface
before measuring.
4. The meter may not make accurate measurements through transparent surfaces such as glass.
5. Steam, dust, smoke, etc. can obscure measurements.
6. To find a hot spot, aim the meter outside the area of interest then scan across (in an up and
down motion) until the hot spot is located.