How to Test a Switch With an Ohm Meter

by Contributor

This article discusses how to test a switch with an ohm meter. Photos show how to connect the ohm meter to the switch for testing.

Familiarize Ohm Meter Functions
1

Verify ohm meter operation. Turn on the multimeter. Select the ohm meter function. Set the resistance range to 'x1.' Skip this step if the ohm meter has 'autorange' capability.

2

Insert the leads into the meter Touch the probe tips together to verify that ohm meter is functioning. With the probes touching, the meter should display 1 ohm or less. A high reading or no reading means that is something wrong with the meter. Go back and check the setup or get another meter.

Connect Ohm Meter to Switch
3

Connect the red lead to one of the terminals on the switch. Connect the black lead to the other terminal on the switch. Put the switch into the ON position. The meter should display 1 ohm or less, meaning the switch is 'ON.'

Ohm Meter with Switch in OFF Position
4

Put the switch into the 'OFF' position. The meter should display 'OL' or a very high resistance, meaning the switch is 'OFF.'

Operate Switch to Verify Function
5

Operate the switch on and off for a few more times.

If the meter display changes from 'ON' condition to 'OFF" condition, the switch operates normally. If the display does not change from 'ON' to 'OFF' condition, then the switch is defective. Purchase a new switch to replace the defective switch, then throw the defective switch away.

Tip

  • check When removing wires from the switch, use masking tape to label which wire connects to which terminal of the switch. This is especially important when the switch has more than 2 terminals.

Warnings

  • close Avoid possible electric shock by turning off the circuit breaker feeding electrical power to the switch.
  • close Replace the defective switch with the same type and size.

Items you will need

About the Author

This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us.

Photo Credits

  • photo_camera Mary K. Lynch