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How to Test an Ohm Meter

An ohm meter measures the amount of resistance present in an electrical circuit; ohms are the unit of measurement. According to the Nondestructive Testing Resource Center, too much resistance in a circuit can cause wires to overheat and can cause a fire; too little resistance can result in the circuit not being able to get the electrical energy where it needs to go. There are two types of ohm meters: analog meters, which display the resistance using a needle and a scale; and digital meters, which display the resistance on an LCD screen.


Analog Meter


Step 1

Plug the two test leads into the meter.  The polarity of the input jacks will be denoted by a plus or minus symbol.

Plug the black lead into the negative (-) input jack, and the red lead into the positive (+) input jack. 


Step 2

Turn the meter’s function/range selector (the large dial in the center of the meter) so that it points to the meter’s lowest range.  This is typically one click to the left of the “off” position.


Step 3

Short the test leads together by touching the metal ends of the leads together. 


Step 4

Wait for the needle on the display to stabilize.  This should take 2 to 3 seconds.


Step 5

Observe which value the needle is pointing toward on the display.  This value is referred to as the “reading” If the reading is 0 ohms then you are finished and your meter is ready for use.

If the reading is between 0 and 10 ohms, proceed to Step 7.  If the reading is greater than 10 ohms, continue to the next step.


Step 6

Obtain a different pair of leads and repeat Steps 1 through 4.  If the reading is now under 10 ohms then the leads you previously used are bad and should be discarded.

If the meter continues to display a high reading, then the fault is with the meter and it needs to be adjusted. 


Step 7

Adjust the meter by turning the ohms adjustment knob until the needle on the display points to 0 ohms.  Your meter is now ready for use.


Digital Meter


Step 1

Plug the two test leads (“leads”) into the meter.  The polarity of the input jacks will be denoted by a plus or minus symbol.

Plug the black lead into the negative (-) input jack, and the red lead into the positive (+) input jack. 


Step 2

Turn the meter on. 


Step 3

Short the test leads together by touching the metal ends of the leads together. 


Step 4

Wait for the numeric value shown on the display to stabilize.  This should take 2 to 3 seconds.

This value is referred to as the “reading” If the reading is 0 ohms then you are finished and your meter is ready for use.  If the reading is greater than 5 ohms, continue to the next step.

If the reading is between 0 and 5 ohms, then subtract this number from all of the readings you obtain from the meter during this use.  This amount of resistance is likely caused by the individual leads.

If you will be taking a large number of readings, and want to zero the meter for these particular leads, then proceed to Step 6. 


Step 5

Obtain a different pair of leads and repeat Steps 1 through 4.  If the reading is now under 5 ohms, then the leads you previously used are bad and should be discarded.

If the meter continues to display a high reading, then the fault is with the meter and it needs to be adjusted. 


Step 6

Adjust the meter by shorting the leads together and inserting a blunt non-magnetic object, such as the tip of a ball point pen, into the calibration pinhole.  This will zero the meter.

Things You Will Need

  • Ohm meter
  • 2 test leads

About the Author

Morgan Owens has a Bachelor of Science in criminal justice, and minors in biology and psychology. She attended Boston University and is currently applying to law school for matriculation in 2014. Her articles have been published on numerous informational websites.

Photo Credits

  • digital multimeter 3 image by dinostock from Fotolia.com