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
WARNING
CAUTION
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
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.
WARNING: Disconnect the test leads before making clamp measurements.
1. Rotate the Function switch to the 400A
AC/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 40A
AC/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 V jack.
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
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
3. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive
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.
.
capacitance position.
jack.
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.
4. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive A jack.
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 “- - - -” .
3. Aim the infrared sensor (rear of the meter) at the surface
to be measured.
4. Press the IRT
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.
button to turn on the IR thermometer
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.
To freeze the LCD reading, press the HOLD button. While data hold is active, the HOLD icon
appears on the LCD. Press the HOLD button again to return to normal operation.
MAX/MIN
1. Press the MAX/MIN button to activate the MAX/MIN recording mode. The display icon "MAX"
will appear. The meter will begins recording and displaying the maximum value measured.
2. Press the MAX/MIN button and “MIN” will appear. The meter will display the minimum value
measured during the recording session.
3. Press the MAX/MIN button and “MAX MIN” will appear. The meter will display the present
reading, but will continue to update and store the max and min readings.
4. To exit MAX/MIN mode press and hold the MAX/MIN button for 2 seconds.
Peak Hold
When ACA or ACV is selected, pressing the PEAK button enables the peak capture circuit. The
meter will now capture and display the maximum and minimum peaks of the waveform.
RANGE
In the Voltage, Resistance, Capacitance, Frequency or uA function the meter automatically selects
the best range for the measurements being made. For measurement situations requiring that a
range be manually selected, perform the following:
1. Press the RANGE button. The “AUTO” display icon will turn off.
2. Press the RANGE key to step through the available ranges. Observe the decimal point and
units displayed until the preferred range is located.
3. To exit the Manual Ranging mode and return to Autoranging, press and hold the RANGE key
for 2 seconds.
LCD Backlight
The LCD is equipped with backlighting for easier viewing, especially in dimly lit areas. Press and
hold the HOLD/
off after 30 seconds.
button for 2 seconds to turn the backlight on. The backlight will automatically turn
Automatic Power OFF with Disable
In order to conserve battery life, the meter will automatically turn off after approximately 30 minutes.
To turn the meter on again, turn the function switch to the OFF position and then to the desired
function position.
To disable APO:
1. From the OFF position, hold the MODE button and rotate the FUNCTION switch to a
measurement function.
2.
3. Release the MODE button
4. APO is now disabled (APO icon is off) and will be reset when the Function switch is returned to
will appear in the display
the OFF position.
Low battery indication
When the icon appears in the display, the battery should be replaced. Refer to the battery
replacement procedure in the maintenance section.
WARNING: To avoid electrical shock, disconnect the meter from any circuit, remove the test leads
from the input terminals, and turn OFF the meter before opening the case. Do not operate the meter
with an open case.
Cleaning and Storage
Periodically wipe the case with a damp cloth and mild detergent; do not use abrasives or
solvents. If the meter is not to be used for 60 days or more, remove the battery and store it
separately.
Battery Replacement
1. Remove the Phillips head screw that secures the rear battery door
2. Open the battery compartment
3. Replace the 9V battery
4. Secure the battery compartment door
5.
Never dispose of used batteries or rechargeable batteries in household waste.
As consumers, users are legally required to take used batteries to appropriate
collection sites, the retail store where the batteries were purchased, or wherever
batteries are sold.
Disposal: Do not dispose of this instrument in household waste. The user is obligated to take end-oflife devices to a designated collection point for the disposal of electrical and electronic equipment.
Other Battery Safety Reminders
o Never dispose of batteries in a fire. Batteries may explode or leak.
o Never mix battery types. Always install new batteries of the same type.
Fuse Replacement
1. Remove the battery
2. Remove the Phillips head screws (2) that secure the rear cover.
3. Replace the fuse with one of equal rating. (200mA, 660V ceramic fast blow, 5x20mm
[SIBA 70-180-40]
Clamp jaw opening 32mm (1.25") approx.
Display Dual 40,000/4,000 count backlit LCD
Non-Contact Voltage 100 to 600VAC
Continuity check Threshold 50; Test current < 0.5mA
Diode test Test current of 0.3mA typical;
Open circuit voltage 2.8VDC typical
Low Battery indication Battery symbol is displayed
Over-range indication ‘OL’ display
Measurement rate 2 readings per second, nominal
Peak detector >1ms
Thermocouple sensor Type K thermocouple required
Fuse 200mA/660V, ceramic, 5x20mm
IR Spectral response 6 to 16µm
IR Emissivity 0.95 fixed
IR distance ratio 8:1
Laser pointer Class 2 laser < 1mW power; Wavelength is 630 to 670nm
Input Impedance 10M (VDC and VAC)
AC bandwidth 50 to 400Hz (AAC and VAC)
AC response True rms (AAC and VAC)
Crest Factor 3.0 in 40A and 400A ranges, 1.4 in 1000A range (50/60Hz and 5% to
Operating Temperature 5C to 40C (41F to 104F)
Storage Temperature -20C to 60C (-4F to 140F)
Operating Humidity Max 80% up to 31C (87F) decreasing linearly to 50% at 40C
Storage Humidity <80%
Operating Altitude 2000meters (7000ft) maximum.
Battery One (1) 9V Battery (NEDA 1604)
Auto power OFF After approx. 30 minutes, with disable
Dimensions & Weight 241x96x44.5mm (9.5x3.8x1.75”); 386g (13.6 oz)
Safety For indoor use and in accordance with the requirements for double
Approvals CE
Patent notice U.S. Patent 7163336
100% of range)
(104F)
insulation to IEC1010-1 (2001): EN61010-1 (2001) Overvoltage
Category III 600V and Category II 1000V, Pollution Degree 2.