Greenlee CM-1050 User manual

999 3257.1 © 1999 Greenlee Textron IM 1401 9/99
CM-1050
CLAMP-ON
AMMETER
AMPERÍMETRO
CON PINZA
PINCE
AMPEREMETRIQUE
INSTRUCTION MANUAL
MANUAL DE INSTRUCCIONES
MANUEL D’INSTRUCTIONS
Read and understand all of the instructions and safety
information in this manual before operating or servicing this tool.
Lea y entienda todas las instrucciones y la información sobre
seguridad que aparecen en este manual, antes de manejar estas
herramientas o darles mantenimiento.
Lire attentivement et bien comprendre toutes les instructions et
les informations sur la sécurité de ce manuel avant d’utiliser ou de
procéder à l’entretien de cet outil.

2
Description
The Greenlee CM-1050 Clamp-on Ammeter is a true RMS-reading meter intended to measure
AC current, resistance, AC/DC voltage and to verify continuity. The large, easy-to-read
3-3/4–digit LCD display has a maximum reading of 3999.
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
This instruction manual is intended to familiarize all personnel with the safe operation and
maintenance procedures for the Greenlee CM-1050 Clamp-on Ammeter.
Keep this manual available to all personnel.
Replacement manuals are available upon request at no charge.
and are registered trademarks of Greenlee Textron.
KEEP THIS MANUAL

CM-1050
3
Important Safety Information
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.
SAFETY ALERT SYMBOL
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 can result in an accident causing serious injury or death.

4
Important Safety Information
Electric shock hazard:
• Do not apply more than the rated voltage between any two input terminals, or
between any input terminal and earth ground.
• Do not contact the test lead tips or any uninsulated portion of the accessory.
Failure to observe these warnings can result in severe injury or death.
Electric shock hazard:
• Do not use the unit if it is wet or damaged.
• Use test leads or accessories that are appropriate for the application. See the
category and voltage rating of the test lead or accessory.
• Inspect the test leads or accessory before use. The item(s) must be clean and dry,
and the insulation must be in good condition.
Failure to observe these warnings can result in severe injury or death.
Electric shock hazard:
Contact with live circuits can result in severe injury or death.
Electric shock and fire hazard:
• Do not expose this unit to rain or moisture.
• 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 can result in severe injury or death.

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5
Important Safety Information
• 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 can result in severe injury or death.
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.
• Do not attempt to repair this unit. It contains no user-serviceable parts.
• Do not expose unit to extremes in temperature or high humidity. See Specifications.
Failure to observe these precautions can result in injury and can damage the instrument.
Do not change the measurement function while the test leads are connected to a
component or circuit.
Failure to observe this precaution can result in injury and can damage the instrument.

6
Identification
1. VΩTerminal
2. COM Terminal
3. Lever
4. Jaw
5. Selector
6. Hold Button
7. Display
HOLD
12
3
4
5
6
7

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Display Icons
8. Low Battery
9. – Polarity
10. DC measurement is selected.
11. AC measurement is selected.
12. Hold function is enabled.
13. K Kilo (103)
14. ΩOhms
15. V Volts
16. A Amps
17. OL or -OL Overload
11
10
9
8
12 15–1613–14
17
Symbols on the Unit
Read the instruction manual.
Double Insulation
Battery
Risk of electric shock

8
AC Measurement
AC measurements are usually displayed as RMS (root mean squared) values. Two methods of
AC measurement are average-responding RMS calibrated and true RMS-reading .
The average-responding RMS calibrated method takes the average value of the input signal,
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, a square wave, sawtooth wave, half wave or signal with harmonics. The ability to read
true RMS provides much more measurement versatility. The Greenlee CM-1050 is a true RMS
meter.
Waveforms and Crest Factors
*The crest factor is the ratio of the peak value to the RMS value; it is represented by the
Greek letter ξ.
mrofevaW
eulaVSMR 001001001001
eulaVegarevA 090017846
*rotcaFtserC
(ξ)
414.1137.12

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Electric shock hazard:
Contact with live circuits can result in severe injury or death.
Operation
1. Set the selector according to the Settings Table.
Settings Table
To measure set the selector connect the and connect the
this value … to this symbol … red lead to … black lead to …
Continuity* ΩVΩCOM
Current (AC) A N/A N/A
Resistance ΩVΩCOM
Voltage (AC) V VΩCOM
Voltage (DC) V VΩCOM
*Tone indicates a circuit resistance is less than 100 Ω.
2. See Typical Measurements for illustrations of typical uses.
3. 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, send the unit to Greenlee for repair.
4. Take the reading from the circuit to be tested.
Note: Press HOLD to hold the present value on the display.

10
Typical Measurements
Clamp Around Wire
Notes:
• Clamp the jaw around one conductor only.
• Close the jaw completely.
• 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.
• Center the line splitter in the jaw for
highest accuracy.