How to Measure Resistance With an Ohm Meter

According to AllAboutCircuits.com, electrical resistance, measured in Ohms, is essentially electrical friction encountered by electrons as they move through a conductor. Ohms are typically symbolized by the Greek letter omega. The easiest way to measure resistance in a circuit is to use an ohmmeter or a multimeter. Most electricians will use a multimeter as it allows them to measure different things with the same instrument. If you are planning on doing any electrical work in your house it's a good idea to have solid grasp on using an ohmmeter.

Things You'll Need

  • An ohmmeter or multimeter

  • Red and black electrical leads

Instructions

Step 1

Select the ohms setting on your multimeter and set it to the highest resistance range available. Some models will auto-set the range for you. If you are using an ohmmeter, set it to the highest resistance range.

Step 2

Plug the black lead into the socket labeled "Com" on your meter. Plug the red lead into the socket marked by the Greek letter omega.

Step 3

Touch the ends of the two leads together. If your meter is properly functioning the display should read 0.0. It may read a slight bit higher, as the leads themselves have resistance, but if it reads over 0.3, you may have a defective meter.

Step 4

Touch each the end of each lead to the end of the wire you wish to measure. Touch the leads to the wire at the same time to complete a circuit. The meter should display a reading of the resistance in ohms of the wire.

Step 5

Make a note of the reading and adjust power as necessary to ensure proper functionality of the circuit.

Tip

Resistance is not usually measured across a complete circuit, rather it should be measured across each potential component of the circuit.

Warning

Never measure resistance across a live, powered circuit. Doing so may damage your meter and even cause personal injury.

References & Resources