How to Test a Power Cord for Ohms

Ohms (generally represented by the symbol Ω) are a measure of the resistance in an electrical circuit. A multimeter or ohmmeter is the tool that is used to check circuits for ohms. These tools are available at almost any store that sells electronics and electronic components. If you have a power cord that is not working properly, you can check it for an open circuit or other issues using a multimeter or ohmmeter set to check for resistance.

• 1

  Set the multimeter to the lowest possible resistance setting (denoted by a "Ω" for ohms) on its dial. Touch the red and black probe together and ensure that the meter reads zero to show that there is no resistance between the probes. Set an analog meter so that it that it shows zero when the probes are touching if it gives a resistance reading.

• 2

  Unplug both ends of the power cable from the computer or other electronic device it powers.

• 3

  Place the black probe at one end of the cable and the red probe at the other end of the cable. Ensure you are touching the metal; the plastic or rubber parts are insulated and will not provide a good reading. Check that the ohmmeter shows a reading of zero to demonstrate that the power cord is not producing any resistance; if the cord shows a high ohm reading or infinite resistance it is probably defective.

• 4

  Touch the red probe to one prong and the black probe to the other prong on the same end of the cord to check for shorted ends of the cable if the cable itself is not showing resistance. Make sure the probes are touching metal. Check that the ends do not show high ohm readings.

• 5

  Replace the defective power cord if it show a high ohm reading during any of these tests.