GREENLEE CM-450 Digital Clamp Meter Instruction Manual

: June 11, 2024
: GREENLEE

GREENLEE CM-450 Digital Clamp Meter

Description

Read and understand all of the instructions and safety information in this manual before operating or servicing this tool.

The Greenlee CM-450 Digital Clamp-on Meter is a hand-held testing device capable of measuring up to 600 amps of alternating current, in addition to measuring AC or DC voltage, frequency, and resistance. It also checks diodes and verifies continuity. The CM-450 is a true RMS-reading meter.

Safety

Safety is essential in the use and maintenance of Greenlee tools and equipment. This instruction manual and any markings on the tool provide information for avoiding hazards and unsafe practices related to the use of this tool. Observe all of the safety information provided.

Purpose of This Manual

This instruction manual is intended to familiarize all personnel with the safe operation and maintenance procedures for the Greenlee CM-450 Digital Clamp-on Meter.
Keep this manual available to all personnel.
Replacement manuals are available upon request at no charge at www.greenlee.com.

Do not discard this product or throw away!
For recycling information, go to www.greenlee.com.

Lifetime Limited Warranty

Greenlee Tools, Inc. warrants to the original purchaser of these goods for use that these products will be free from defects in workmanship and material for their useful life, excepting normal wear and abuse. This warranty is subject to the same terms and conditions contained in Greenlee Tools, Inc.’s standard one-year limited warranty.
For all Test Instrument repairs, contact Customer Service at 800-435-0786 and request a Return Authorization.
For items not covered under warranty (such as items dropped, abused, etc.), a repair cost quote is available upon request.
Note : Prior to returning any test instrument, please check replaceable batteries or make sure the battery is at full charge.

All specifications are nominal and may change as design improvements occur.
Greenlee Tools, Inc. shall not be liable for damages resulting from misapplication or misuse of its products.
® Registered: The color green for electrical test instruments is a registered trademark of Greenlee Tools, Inc.

Important Safety Information

SAFETY ALERT SYMBOL

This symbol is used to call your attention to hazards or unsafe practices which could result in an injury or property damage. The signal word, defined below, indicates the severity of the hazard. The message after the signal word provides information for preventing or avoiding the hazard.

Immediate hazards which, if not avoided, WILL result in severe injury or death.

Hazards which, if not avoided, COULD result in severe injury or death.

Hazards or unsafe practices which, if not avoided, MAY result in injury or property damage.

Read and understand this material before operating or servicing this equipment. Failure to understand how to safely operate this tool could result in an accident causing serious injury or death.

Electric shock hazard:
Contact with live circuits could result in severe injury or death.

Electric shock and fire hazard:

Do not expose this unit to rain or moisture.
Do not use the unit if it is wet or damaged.
Only use the test leads provided with the equipment or UL Listed Probe Assembly with same rating or better.
Inspect the test leads or accessory before use. They must be clean and dry, and the insulation must be in good condition. Do not use the test lead if the contrasting inner layer of insulation is visible.
Use this unit for the manufacturer’s intended purpose only, as described in this manual. Any other use can impair the protection provided by the unit. Failure to observe these warnings could result in severe injury or death.

Electric shock hazard:

Do not operate with the case open.
Before opening the case, remove the test leads (or jaw) from the circuit and shut off the unit.

Failure to observe these warnings could result in severe injury or death.

Electric shock hazard:

Using this unit near equipment that generates electromagnetic interference can result in unstable or inaccurate readings.
Unless measuring voltage or current, shut off and lock out power. Make sure that all capacitors are discharged. Voltage must not be present.
Failure to observe these warnings could result in severe injury or death.

Electric shock hazard:

Do not attempt to repair this unit. It contains no user-serviceable parts.
Do not expose the unit to extremes in temperature or high humidity. Refer to “Specifications.”

Failure to observe these precautions may result in injury and can damage the unit.

Electric shock hazard:

Do not change the measurement function while the test leads are connected to a component or circuit.
Failure to observe this precaution may result in injury and can damage the unit.

Statement of Conformity

Greenlee Tools, Inc. is certified in accordance with ISO 9001:2008 for our Quality Management Systems.
The instrument enclosed has been checked and/or calibrated using equipment that is traceable to the National Institute for Standards and Technology (NIST).

Identification

Jaw
Position error marks
Jaw center marks
Lever
Hold button
Relative measurement button
Display
Select button
Frequency button
Selector switch
Negative, common (COM), or ground input terminal
Volts or resistance (VΩ) input terminal

Display Icons

Auto ranging is enabled.
Diode test
Continuity mode
Hold function is enabled.
Low battery indicator
Relative measurement is enabled.
M Mega (106 )
Ω Ohms
Hz Hertz
k kilo (103)
A Amps
V Volts
m milli (10-3)
O.L. Overload indicator
– Negative polarity indicator
AC measurement is selected.
DC measurement is selected.

Symbols on the Unit

Warning—Read the instruction manual
Application around or removal from hazardous live conductors is permitted.
Double insulation

Using the Features

Selector Switch

Slide switch to desired mode of operation:
AC voltage
DC voltage
AC current
ohms/continuity/diode
Return switch to OFF position when not in use.

Select Button (SELECT)

Momentarily press to select resistance, continuity, or diode test when the Selector switch is set to .

Frequency Button (Hz)

Press to measure frequency.

Note : The sensitivity of the frequency measurement function varies with the measurement range. To automatically select a sensitivity level, measure the voltage level first, and then press Hz. Pressing Hz before making a measurement may give higher sensitivity. Reading may be zero when sensitivity is too low.
Electrical noise may cause unstable readings.

Hold Button (HOLD )

Press momentarily to hold the present value on the display. will appear on the display.
Press again to return to normal mode.

Relative Measurement Button ( )

This feature finds the difference between two measurements.

While taking a measurement, press to set the display to zero. will appear on the display.
Take the second measurement. The value on the display will be the difference between the two measurements.
Press again to exit this mode.

Auto Power Off

To extend battery life, the meter will shut itself off after approximately 30 minutes of inactivity. To restore power, press any button.

AC Measurement

AC measurements are usually displayed as RMS (root mean square) values. The RMS value is equal to the value of a DC waveform, which would deliver the same power if it replaced the time-varying waveform. Two AC measurement methods are average-responding RMS calibrated and true RMS-reading.
The average-responding RMS calibrated method takes the average value of the input signal after full wave rectification, multiplies it by 1.11, and displays the result. This method is accurate if the input signal is a pure sine wave.
The true RMS-reading method uses internal circuitry to read the true RMS value. This method is accurate, within the specified crest factor limitations, whether the input signal is a pure sine wave, square wave, triangle wave, half wave, or signal with harmonics. The ability to read true RMS provides much more measurement versatility. The Greenlee CM-450 is a true RMS meter.
The Waveforms and Crest Factors table shows some typical AC signals and their RMS values.

Waveforms and Crest Factors

Waveform| | | |
---|---|---|---|---
RMS Value| 100| 100| 100| 100
Average Value| 90| 100| 87| 64
**Crest Factor* ( )**| 1.414| 1| 1.73| 2

The crest factor is the ratio of the peak value to the RMS value; it is represented by the Greek letter .

Operation

Electric shock hazard:
Contact with live circuits could result in severe injury or death.

Set the Selector switch according to the Settings Table. Momentarily press the SELECT button to select mode.
Refer to “Typical Measurements” for specific measurement instructions.
Test the unit on a known functioning circuit or component.
• If the unit does not function as expected on a known functioning circuit, replace the battery.
• If the unit still does not function as expected, call Greenlee for technical assistance at 800-435-0786.
Take the reading from the circuit or component to be tested.

Settings Table

To measure this value . ..| Set the Selector switch to this symbol .. .| This icon will appear on the display. ..| Connect red lead to .. .| Connect black lead to .. .
---|---|---|---|---
AC Current* (600A max.)| | and A| N/A| N/A
Frequency of a current (600A max.)|

and press Hz

| Hz| N/A| N/A
Voltage (600 V max.)| | and V| +| COM
| and V
Frequency of a voltage signal|

or and press Hz

| Hz| +| COM
Resistance| | MΩ| +| COM
Continuity**|

and press SELECT

| Ω| +| COM
Diode|

and press SELECT 2 times

| and V| +| COM

Typical Measurements

AC Amps

Clamp Around Wire
Notes:

Clamp the jaw around one conductor only.
Close the jaw completely to ensure accurate measurement.
Center the wire in the jaw for highest accuracy

Clamp Around Line Splitter

Notes:

The Greenlee 93-30 Line Splitter is divided.
One section renders amps; the other renders amps multiplied by 10.
Close the jaw completely to ensure accurate measurement.
Center the line splitter in the jaw for highest accuracy.

Voltage

Resistance

Continuity

Diode Test

Accuracy

Refer to “Specifications” for operating conditions and temperature coefficient. Accuracy is specified as follows: ± (a percentage of the reading

a fixed amount) at 23 °C ± 5 °C (73.4 °F ± 9 °F), 0% to 75% relative humidity.
True RMS readings: Voltage is specified from 5% to 100% of the range, and AC current is specified from 10% to 100% of the range, unless otherwise specified.
Frequency must be within the specified bandwidth for non-sinusoidal waveforms. Crest factors are as follows:
- Crest Factor < 1.75 at full scale
- Crest Factor < 3.5 at half scale

AC Current

Measurement Range	Accuracy	Frequency Range
0.40 to 40.00 A	± (1.5% + 0.08 A)	50 to 60 Hz
40.0 to 400.0 A	± (1.5% + 0.8 A)
400 to 600 A	± (1.5% + 8 A)

Adjacent conductor influence < 0.05 A/A
Add 2% if the conductor is beyond the position error marks.
Multiply the fixed error amount times 2 below 10% of range.

AC Voltage

Measurement Range| Accuracy| Frequency Range| Input Impedance
---|---|---|---
4.000 V| ± (1.5% + 0.005 V)| 50 to 500 Hz| 10 MΩ // 30 pF nom.
40.00 V| ± (1.5% + 0.05 V)
400.0 V| ± (1.5% + 0.5 V)
600 V| ± (2.0% + 5 V)

DC Voltage

Measurement Range	Accuracy	Input Impedance
400.0 mV	± (0.3% + 0.4 mV)	1000 MΩ*
4.000 V	± (0.5% + 0.003 V)	10 MΩ
40.00 V	± (0.5% + 0.03 V)
400.0 V	± (0.5% + 0.3 V)
600 V	± (1.0% + 4 V)

The high impedance on this range will produce significant non-zero readings when the test leads are disconnected from a circuit.

Resistance

Measurement Range	Accuracy
400.0 Ω	± (0.8% + 0.8 Ω)
4.000 kΩ	± (0.6% + 0.004 kΩ)
40.00 kΩ	± (0.6% + 0.04 kΩ)
400.0 kΩ	± (0.6% + 0.4 kΩ)
4.000 MΩ	± (1.0% + 0.004 MΩ)
40.00 MΩ	± (2.0% + 0.04 MΩ)

Diode Tester

Test Current	Open Circuit Voltage
0.25 mA typical	1.6 VDC maximum

Frequency

Function	Sensitivity (Sine RMS)	Range
400.0 mV	350 mV	10 Hz to 2 kHz
4.000 V	1 V	10 Hz to 5 kHz
40.00 V	32 V	10 Hz to 100 kHz
400.0 V	100 V	10 Hz to 10 kHz
600 V	500 V	10 Hz to 5 kHz
400.0 A	60 A	40 Hz to 400 Hz

Accuracy of Frequency Ranges

Display Range	Accuracy
5.000 Hz	± (0.5% + 0.004 Hz)
50.00 Hz	± (0.5% + 0.04 Hz)
500.0 Hz	± (0.5% + 0.4 Hz)
5.000 kHz	± (0.5% + 0.004 kHz)
50.00 kHz	± (0.5% + 0.04 kHz)
500.0 kHz	± (0.5% + 0.4 kHz)

Specifications

Display : 3-3/4-digit LCD (4000 maximum reading)
Sampling Rate : 3 per second
Overrange Indication : “OL” appears on the display
Maximum Conductor Diameter : 26 mm (1.02″)
Measurement Category : Category III, 600 V
Temperature Coefficient : 0.15 x (specified accuracy) per °C below 18 °C or above 28 °C
Operating Conditions : At 0% ≤ 80% RH: 5 °C to 31 °C (41 °F to 86 °F) Decreasing linearly to 50% RH at 40 °C (104 °F)
Altitude : 2000 m (6500′) maximum Indoor use only
Storage Conditions : -20 °C to 60 °C (-4 °F to 140° F), 0% to 80% relative humidity with battery removed
Pollution Degree : 2
Battery : 3 V standard button battery (IEC-CR2032; ANSI-NEDA-54004LC)
CENELEC Directives : The instruments conform to CENELEC Low-voltage directive 2006/95/EC and Electromagnetic compatibility directive 2004/108/EC
Safety : Double insulation to IEC/UL/EN61010-1 Ed. 3.0, IEC/EN61010-2-032 Ed.
3.0, IEC/EN61010-2-033 Ed. 1.0, IEC/UL/EN61010-031 Ed. 1.1 and CAN/CSAC22.2 No. 61010-1-12 Ed. 3.0
All Terminals : CAT III 600 V AC/DC

Measurement Categories

These definitions were derived from the international safety standard for insulation coordination as it applies to measurement, control, and laboratory equipment.
These measurement categories are explained in more detail by the International Electrotechnical Commission; refer to either of their publications: IEC 61010-1 or IEC 60664.
Measurement Category I : Signal level. Electronic and telecommunication equipment, or parts thereof. Some examples include transient-protected electronic circuits inside photocopiers and modems.
Measurement Category II : Local level. Appliances, portable equipment, and the circuits they are plugged into. Some examples include light fixtures, televisions, and long branch circuits.
Measurement Category III : Distribution level. Permanently installed machines and the circuits they are hard-wired to. Some examples include conveyor systems and the main circuit breaker panels of a building’s electrical system.
Measurement Category IV : Primary supply level. Overhead lines and other cable systems. Some examples include cables, meters, transformers, and other exterior equipment owned by the power utility.

Maintenance

Electric shock hazard:

Do not attempt to repair this unit. It contains no user-serviceable parts.
Do not expose the unit to extremes in temperature or high humidity. Refer to “Specifications.”

Failure to observe these precautions may result in injury and can damage the unit.