How
to Use Electrical Circuit Testers in Home Electrical Wiring
By Mark J. Donovan
When working with electricity,
particularly high voltage AC electricity in your home, it is always
important to employ a high level of safety precautions. Part of that safety
begins with shutting off power off at the main circuit panel to the circuits
that you plan on working on. The other part of the safety equation is
confirming that the power is indeed off at the electrical box or appliance
you plan on working on. To do this requires the use of an electrical circuit
tester.
There are variety a of electrical
circuit testers available on the market today, however there are two that
are most commonly used.
High Voltage AC Circuit Tester
(a.k.a. - Neon Bulb Tester)
One common electrical circuit
tester is the High Voltage AC Circuit tester, or Neon bulb tester. It is
inexpensive, requires no batteries, and is easy to store due to the fact
that it is so small. Most models will support an AC voltage up to 250V.
Photo By Mark Donovan
To use a High Voltage Circuit tester,
just plug the two terminals into the wall outlet, or switch box you plan on
working on, making sure that you are holding onto the insulated handles and are
not touching the metal probes. If you touch the metal probes while plugging them
into a powered outlet or circuit you may be exposed to a life threatening shock.
If the outlet or switch is powered
on, the bulb will light up. If it is not, the bulb will remain unlit.
You can also use this type of tester
to check if power is flowing through a switch, or on bare wire ends, or even on
a circuit breaker. Again, extreme caution should be given while performing any
of these types of tests.
Digital Multimeter
Another electrical circuit tester is
a digital multimeter. It can be used for a number of electrical circuit testing
applications.
First, it can be used to measure
High Voltage AC at a circuit breaker, outlet, or switch, using the two
probes that come with it. To use it for this type of test, plug the black
lead into the common socket, and the red lead into the Voltage/Ohm socket.
Then set the dial for 125AC or higher, depending upon the digital multimeter
model that you have. Next plug the leads into the outlet or across the
switch and read the digital display on the digital multimeter. You should
observe a reading of somewhere between 110 and 120V if power is on at the
outlet, switch or circuit breaker.
You can also use a digital multimeter for checking
connectivity between two points in a circuit. To do this, again plug the
black lead into the common socket, and the red lead into the Voltage/Ohm
socket. Now set the dial to Ohms, for a resistive load. Now touch the
two probes together.
Photo By Mark Donovan
You will notice that the reading goes to a value of Zero, indicating that
there is direct connectivity, or a short between the two probes. You can
extend this function for testing the connectivity between a length of wire
or un-powered circuit. For, example you can use a digital multimeter to
“buzz out” the Romex cables between two electrical boxes.
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This situation frequently arises
when you are in the process of doing the finished wiring in a room and are
not sure which Romex cable end coming out of one box corresponds with
another Romex cable end in another box. By twisting, for example, the black
and white wires together coming from the same Romex cable end, you can then
check for connectivity between the two wires at the far end, or other
electrical box. When you find the Romex cable at the far end box that has a
short between the black and white wires (because you tied them together at
the other box) you can then label the Romex bundle at both ends.
Digital multimeters can also be
used for measuring resistance and current.
Though digital multimeters are
more expensive and cannot be as easily stored in a pant or shirt pocket they
do offer some significant advantages over High Voltage AC Circuit Testers
and are thus well worth the extra investment.
So before working with
electricity in your home, make sure you have a High Voltage AC Circuit
tester or a Digital multimeter, and always exercise extreme caution by first
turning power off at the main circuit panel, and then checking that power is
indeed off at the particular electrical box.
Warning: When working with electricity use extreme
caution to avoid the risk of electrical shock. Make sure to first shut off
power at the main circuit panel and then confirm all
power to the electrical fixtures and boxes are off prior to beginning any
electrical work.
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Additional Home Electrical Wiring Resources
for Wiring Ceiling Fans
Electrical Circuit Testers from Amazon.com
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