How To Use A Multimeter





Learning how to use a multimeter can be very confusing when you are trying to understand resistance,ohms,continuity and infinity.

The purpose of this page is to teach you (in a non technical way) to use a analog multimeter to test circuits or voltage in or around your home and to check water heater elements and thermostats.

Electrical meters can range in prices from ten dollars to hundreds of dollars. For home users I recommend a fuse protected meter. If you make a mistake the fuse will protect the meter.
Analog meters are easy to read and understand and they are more affordable.



What is an analog multimeter?

An analog meter uses a needle to measure voltage and continuity.

The analog meter in the pic is very inexpensive and can be used to check AC or DC voltage and continuity.





What is continuity?

Simply put, continuity means uninterrupted or no resistance.

Suppose we test a light switch for continuity. With our meter dial set on RX1 the needle would sweep across the face of the meter and stop on zero . This tells us that we have zero resistance. The circuit on this switch is uninterrupted, 120 volts can flow through this switch.
The switch is good.

Now suppose the needle stops half way across the face and does not go to zero. This means that we have resistance or an interruption in the circuit. It could be corrosion or rust or a worn circuit. 120 volts cannot flow through this circuit. The switch should be replaced.

A continuity test is used to check wires,circuits, switches and parts.

If an electrical device has stopped working, the flow of electric has
been interrupted. A continuity test can be used to find the interruption.



Setting up your meter to check continuity or resistance.

Set the dial on your multimeter
to RX1.




Touch the two meter probes together (see pic).
The needle should moved all the way across the face of the meter and stop on zero.

The thumb wheel on the side of the meter is used to adjust the needle if it does not stop on zero.
While touching the two probes together move the thumb wheel until the needle is on zero.



How to test a light switch

All continuity test should be done with the power off. Any wires that may interfere with the test should be removed.

Multimeter's have a black
and red probe.
When doing a continuity test
it does not matter which probe
goes where.

To test a light switch, place a probe on each of the terminal screws.

With the switch off, you should not get a reading.

With the switch on, the needle should sweep over to zero.




How to use a multimeter to check a wall outlet

To check ac voltage set
your multimeter dial to the
proper ac value.

The ac value on this meter
jumps from 50 to 250 volts.
We know the standard wall
outlet is 120 volts so this meter
must be set on 250 volts ac.

Always set the value higher than the voltage you're testing.



To check a wall outlet set your meter at a value above 120 volts.

Insert both probes into the
outlet as shown.

This outlet is reading 120 volts.

Always check your multimeter on
an outlet that you know is working
before you trust it to check something else.



How to read a multimeter when checking DC voltage

To check dc voltage set your dial to dc at a voltage higher than what your checking.

We're going to check a car battery and we know its 12 volts so we'll have to set the valve at 50 volts on this meter.



When checking dc voltage you must use the red probe for positive (+) and the black probe for negative (-)

This car battery is reading
13 volts dc which is correct.




How to use a multimeter - how to read a multimeter

Safety and buying tips for an analog multimeter

Always buy a meter that is fuse protected. If you check something with the meter on the wrong setting the fuse will blow instead of burning up the meter.

Always check your meter before every test to be sure its working
properly

Never trust a multimeter 100 percent when checking ac voltage.
Always hold an ac wire by the plastic insulation and use tools with
insulated handles.

Never touch the metal tips of the multimeter probes when testing.

Set the multimeter value higher than the device you're checking

All continuity test are done with the power off.

Please learn how to use a multimeter safely before checking anything with exposed wires and the power on.



Related pages

How to check the power coming into your water heater, click here.

Test an electric water heater thermostat, click here.

How to check a water heater element, click here.







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