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
The analog meter in the
pic is very inexpensive and can be
used to check AC or DC voltage
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
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
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
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
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
Never trust a multimeter 100 percent when checking ac voltage.
Always hold an ac wire by the plastic insulation and use tools with
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.
How to check the power coming into your water heater,
Test an electric water heater thermostat, click here.
How to check a water heater element, click here.
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