How to Measure Electrical Resistance
Electrical resistance is the measurement used to determine the flow of electrical current and how much that flow is impeded. This is a common test used in the troubleshooting of various electronic problems. The most important thing to remember when testing for resistance is that the power to the item to be tested should always be OFF. Here is how you can measure electrical resistance. Does this Spark an idea?
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Instructions
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Before you perform the test, be sure to turn the power OFF to whatever you are going to be testing. If you don't you can further damage your equipment and quite possibly your multitester as well.
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It also helps to have an understanding of what the expected resistance should be in the piece of equipment you are planning on testing. If it is a resistor, then the colored rings can give you an idea of what the resistance level should be. You may also want to consult the documentation that came with your equipment.
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Set the multimeter to read ohms. This setting features a figure that resembles an "O" with feet, otherwise known as the Omega sign. If your tester has numerous settings under the ohm section, choose the range that your equipment is rated at. For instance, if the resistor you are testing is rated at 270k ohms, then you will want to set your tester to read within that range on the setting dial.
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With your tester set and the power off, touch one probe tip to one end of the resistor and the other probe tip to the other end, making sure to keep contact on the metal wire elements.
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The tester should now read the resistance of the resistor. You will notice that the readout will change from infinity to whatever the resistance reading is on the resistor. If the resistor is bad, then you will either get no reading or a different resistance reading than what it is rated at.
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Tips & Warnings
Never test for resistance with the power on.
Always make sure you have your tester properly set to read ohms when testing for resistance.
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Comments
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nowayxxx
Jun 23, 2009
if i can't disconnect power as in a no break network how can i measure the resistance of a contact to know if it's damaged or not. -
hvacteacher
Feb 04, 2009
In another article you wrote on using electrical meters you stated that you can not read amperage with an electrical meter with leads. You can use a vom meter to measure amperage, you just have to attach the leads in series with the load.
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hvacteacher
Feb 04, 2009
In another article you wrote on using electrical meters you stated that you can not read amperage with an electrical meter with leads. You can use a vom meter to measure amperage, you just have to attach the leads in series with the load.
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ElectricianDave
Oct 22, 2008
Dave - your article is very well done!
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ElectricianDave
Oct 22, 2008
Dave - your article is very well done!
