How To Use a Multi-Meter

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First, what is a multi-meter?  The simple definition is "an instrument for measuring electrical resistance". So without getting all complicated and with electrical terms and such, basically it is a little hand-held meter that you can use to test things like batteries, light bulbs, and electrical currents.

Yesterday I showed you how my dad and I replaced my back porch light with a new light fixture. Normally you will probably know which breaker goes to each of the lights in your house… that's easy to determine by just switching off the breaker and if the light goes out then you've got the correct breaker.

However, in my situation the breaker wasn't marked and the light wasn't working so I couldn't easily find the correct breaker.

Today I want to show you one method for figuring this out. You can test the wiring after you've removed the old light or just the light bulb with a multi-meter. 

How to use a multi-meter

Here is that offensive (in so many ways) light again.

To get started turn the multi-meter to AC. This stands for Alternating Current which is what the wiring in your house is. Set the dial for the next higher setting than what you are testing for. Most house wiring is 120 volt (240 volt is used on things like dryers and ranges) so on my multi-meter the next higher setting is 250. You will notice that the AC settings near the dial are in red so the readings I will read on the analog display will also be in red.

So, with your multi-meter set to the proper settings for testing AC voltage, remove the light bulb from the socket of your light fixture and touch the test probes from the multi-meter to the metal parts where the light bulb would have been.  If the pointer on the dial doesn't move then the electricity is not live. If it moves at all then there is some voltage running through the wires in your house to the fixture.

Note that this is how it should work... again... my light was difficult and it wasn't as easy as just unscrewing a light bulb. We couldn't get the cover off the light to get to the bulb so we opted to remove the entire light fixture and test the bare wires.

A word of caution if you choose to do it the way we did... Safety first!! When you are unsure if the wiring is live do NOT touch the white and black wires together and do NOT touch the wiring with your hands or any metal items like screwdrivers, etc.(the metal probes ends are fine because the parts you hang onto are plastic) until you are sure it is not live (no electricity running to it)!

So in my case, once my dad touched the probes to the wires then I started flipping breakers until the pointer on the dial went down to zero, then I knew which breaker controlled that light and I marked it!

To test light bulbs turn the dial on the multi-meter to "Ohm" which is a unit used in the international system of measurements to measure resistance... whatever right?! Just turn it to Ohm :o)

Red probe goes on the side of the light bulb where the threads are and the black goes on the end of the light bulb. If the meter has a reading then the light bulb is good!

And this one is especially helpful... testing batteries! No more trying 50 batteries and none of them work!!

To test batteries, turn the multi-meter to DC. This stands for Direct Current which is what batteries are.

Put the black probe on the bottom of the battery and the red probe on the end with the raised tip.

If the meter has a reading the battery is good!

So that my friends is how to use a multi-meter. There are many different kinds and brands of multi-meters and each one may be a little different so be sure to read the directions before you begin, but this is the basic idea behind them, I hope you found this informative and maybe you'll want to give it a try!

Here are some that you can purchase on Amazon.

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  1. Very thorough and understandable explanation. I think i understand that confounded little contraption a bit better now!

  2. I love technical articles like this :D Looks like a useful devise to have around, I honestly hadn't heard of it until this post.

    1. Thanks Vanessa, I'm glad you liked the post :o) I feel like so many women think they can't do some things without a man... like replacing light fixtures... I wanted to share how easy it really is!



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