Checking continuity in a long wire

Content

What is continuity?
Using a multimeter
Steps to Test Continuity in a Long Wire
Notes and other reminders

Trying to fix faulty electronics but can't figure out what's wrong?

The problem may just be in plain sight. People tend to overlook the condition of long wires when repairing electronics. Electrical wires are designed to last for years, but other factors such as rough handling and exposure to the elements can cause them to break. Checking wires for continuity is the only way to ensure your wire is still working.

Speed up repairs by learning how to test a long wire for continuity.

What is continuity?

Continuity exists when two objects are electronically linked.

Wires conduct electricity, so you established continuity by connecting a simple switch to a light bulb. Likewise, a material that does not conduct electricity, such as wood, does not provide continuity. This is because the material does not electronically connect two objects.

At a deeper level, continuity exists when the conductive path of an electric current is not interrupted.

Electrical wires are conductors and resistors. It controls the flow of electrons and ions to and from each end. Continuity indicates how well electricity flows through a wire. A good continuity reading means that all wire strands are good.

The continuity test checks the integrity of the electronics and electrical components. This is done using a tester circuit to measure the resistance value.

Lack of continuity causes many problems with electronics and components, such as:

Blown fuse
Switches not working
Blocked chain paths
Shorted conductors
Faulty wiring

Using a multimeter

A multimeter is an essential tester circuit for any electronics related projects.

This handheld instrument measures electrical parameters such as voltage, capacitance and resistance. It comes in analog and digital versions, but the basic purpose and details remain the same. It comes with two lead probes, a positive red wire and a black negative wire, which measure electrical values when in contact with electronics.

A cheaper analog multimeter works well as a continuity tester, but you may also want to invest in digital multimeters for their extra features and more accurate readings. DMMs sometimes have a special continuity test feature.

Steps to Test Continuity in a Long Wire

Now that you understand the basics of continuity, it's time to learn how to test a long wire for continuity.

The only tool you will need to test for continuity is a simple multimeter. But remember to stay safe by wearing basic protective gear while doing this test.

Step 1 - Turn off the power supply and disconnect the wire

Never test the integrity of a live wire.

Turn off the main circuit that supplies electricity to the wire. Make sure that no electricity is running through the wire, as a live wire can cause undesirable consequences.

Disconnect the wire from any connected components and the circuit itself.

Safely discharge any capacitors present in the circuit before touching other components. If the wire is connected to components such as switches or lamp sockets, then carefully disconnect the wire from them.

Then remove the wire from the circuit. Do this by carefully pulling the wire out of its connection. Be careful not to damage the wire during this process. Take the completely removed wire to a free working place.

Step 2 - Set up your multimeter

First, turn the dial of the multimeter to ohms.

The display should show "1" or "OL". "OL" stands for "Open Loop"; this is the maximum possible value on the measurement scale. These values mean that zero continuity has been measured.

Connect the test leads to the appropriate sockets on the multimeter.

Connect the black test lead to the COM jack (meaning common). Connect the red test lead to the VΩ connector. Depending on the model of your multimeter, it may have contact points instead of a COM connector. Always refer to the manual if you are not sure about the correct connection of the sensors.

Do not allow the multimeter probes to come into contact with anything before checking for continuity. This may change the readings received. Also pay attention to the order of connecting the wires. This information will be needed later when the multimeter is packed after use.

Set the multimeter's range set to the correct value.

The span value you set determines the resistance of the component. Lower ranges are used for low impedance components. Higher ranges are used to test higher resistances. Setting the multimeter to 200 ohms is enough to check the integrity of long wires.

Step 3 - Connect the multimeter leads to the wire

Continuity is non-directional - no need to worry about connecting sensors to the wrong end. Changing the position of the probes does not affect the resistance measurement.

It is important to connect the probe leads to the metal of the wire. Place one probe on each end of the wire. Make sure the probe is making proper contact with the wire to get an accurate reading.

The measurement taken from this continuity tester should be displayed on the multimeter. You need to look for two dimensions: "1" and other values close to 0.

Values close to zero are interpreted as continuity within the sensors and wire. This means that the circuit is closed or completed. Electricity can flow freely through the wire without any problems.

The value "1" is interpreted as null continuity. This value indicates that the wire circuit is open. This could mean three possible things:

Zero continuity
There is endless resistance
High voltage present

You can delve into the root of the problem, but zero continuity means the wire is not working properly in the first place and needs to be replaced.

Step 4 - Remove and Disassemble the Multimeter

Remove the multimeter after checking for continuity.

The correct way to remove the probes from the multimeter is in the reverse order of assembly. If the red probe was installed last, remove it first, and vice versa. It may seem tedious, but properly disassembling your multimeter will prolong its life.

Turn off the multimeter and put it in a proper storage location. (1)

Notes and other reminders

Before testing continuity, always check that no more electricity is flowing through the wires.

Accidental contact with high voltage often results in electric shock and burns. In some cases, this can result in serious injury or death. Prevent this by ensuring that no current flows through the circuit and its components.

Wearing protective gear is an excellent precaution against electric shock. Although protective equipment is generally not used for simple continuity tests, it is highly recommended. The new multimeters are equipped with overload protection up to a certain nominal voltage. This gives the user some degree of electrical protection. (2)

Always check your multimeter manual for instructions on how to measure resistance.

There are many models of multimeters available on the market, most of which have different functions. Some multimeters come with a continuity button that must be pressed to test for continuity. Newer models even beep when continuity is detected. This makes it easier to check for continuity without having to check the value.

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