How to Test a Light Socket With a Multimeter

How to Test a Light Socket With a Multimeter

You have replaced that old light socket with a brand new one and you want to make sure that it’s functional? You want to test your light socket to make sure that it’s in good order for bulbs? 

If your answer to any of those questions is affirmative, or if you are just curious and love to work with multimeters, you came to the right place.

I will give you advice on how to test a light socket with a multimeter. This will work on all light sockets, from the one on the wall, to the one on the lamp.

Just make sure that you take precautions, like turning the power off, before working on them and testing them.

How to Test a Light Socket With a Digital Multimeter

light socket

Initial preparations and basic concepts

It goes without saying that you need to unscrew the bulb that you want to test from the socket and now is the time to do so.

Once again, make sure that you have turned off the power in the entire household grid if you plan to test the wall sockets, or make sure that you have unplugged the lamp in case that you wish to test the lamp.

In order to conduct the test on the lamp, you will need a power source. You can buy one at your local DIY store. Such a source is necessary for you to test precisely, because it is safe that way and because you can manually set power levels while doing this.

Make sure that you use a multimeter of high quality. If you have to use entry level multimeters, at least make sure that you buy quality fuses. Don’t save any money on the fuses, because the fuses could save your life.

Prepare your multimeter

which fluke multimeter should you buy
  • If you are doing this on the lamp, prepare the power source and plug the lamp in.  If you are working on the light socket in the ceiling it would be best and safer if you would remove it from the ceiling and use your own power source.
  • Take your multimeter and prepare the multimeter standard test leads. If you want a free hand, you can replace the negative black standard probe with an alligator one.
  • Prepare your multimeter and set it to volts -- alternate current setting.
  • Place the red (positive) probe in the volt socket and the black (negative) probe in the common ground socket (on the multimeter).

Connect the black probe to the inner side of the socket

  • Take your black gator probe and connect it to the metal casing that envelops the inside area of the socket. This is possible to do on most sockets because a manufacturer usually leaves a tiny amount of space between the casing and the body.
  • If your gator is too wide or if you do not have enough space between the casing and the socket’s outer body, it will be impossible for you to use the gator clip and you will need to use standard test leads in both multimeter probe sockets.
  • Anyhow, the black test lead needs to touch the inner metallic layer of the socket. Just to avoid confusion, this part of work refers to the metallic ribbed part in which you screw the lightbulb in.

Connect the red probe to the socket central bottom point

Take the red probe and touch the central contact point in the socket.

Central contact point is the point located at the bottom of the light socket. When you screw the bulb in, the bulb tip touches that point and recieves current through it.

Note the results

Multimeter should show you a result of around one hundred and twenty volts.

Results from one hundred and ten to one hundred and thirty volts are considered to be standard values, but anything past them, in either direction, is considered to be too high or too low.


  • Just to be extra sure, wear rubber gloves that can protect you from electricity.
  • If you are not sure what you are doing, it’s best to call in an electrician. You don’t want to short circuit the neighborhood, nor you want to injure yourself or put others in harm’s way.
  • You can find valuable information about socket’s properties on the sockets side. Use it if you want to make sure that your multimeter is set to correct range, or if you want to go online and explore plans of the socket before you begin testing it.

I gave advice to my friend on how to test a light socket in the ceiling when he first moved to his newly bought house.

He had a couple of questions, but he more or less understood what he needed to do and he completed the testing with great success.

All of his sockets were in good order and I hope that the same will apply to your home lighting too when you start using this guide.

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