How to Test a Telephone Wire with a Multimeter

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Telephone wires are normally installed by telephone department staff members skilled in installation work. Installation of telephone cable up to the outer walls of buildings is typically treated as the telephone network of the telephone department. In this post, we shall look at what a telephone wire is and how you can test it with a digital multimeter. 

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What is a telephone wire? How does the telephone work? 

Telephone wiring refers to the structured network of cables that connects your office or home telephone to centralized telephone switching centers worldwide. More and more people are utilizing mobile phones for their telephone needs. However, it is still essential for the efficient communication needs of the world. 

Telephone wirings in a standard home have four different wires: red, green, black, and yellow. They are utilized in pairs for every phone line you have. Repairmen and electricians refer to these wires in terms of pairs. Hence, a standard four-wire telephone line features two pairs. 

The first line utilizes a red-green pair, while the second line uses the yellow-black pair. The cables are relatively tiny, as are the wires inside, and must not be misinterpreted with electrical wires that are much bigger. Take note that the wires are nearly hair-like compared to electrical wires that are bulky and hard to bend. 

Telephone company practices may differ substantially from one locality to another locality. However, the basic principle underlying the way they work stays unchanged. Each telephone is composed of three separate sub-assemblies, each capable of independent operation.

Such assemblies are the ringer or bell, the dialing mechanism, and the speech network. Together, such parts and other devices like dialers, modems, and answering machines are connected to the phone line. 

Common problems with telephone wiring jacks that you need to know

Here is the list of the common problems that many people learned how to fix. 

  • Telephone not working 

There is no dial tone, and the phone is dead and doesn’t work.

  • Issues connected with telephone jack wiring

Remember that telephone wires are extremely small things. So, ensure the wire of different colors isn’t touching one another. Or else that could source the phone service to be obstructed. Further, the junction boxes with phone wires and cables might also have other wires that aren’t connected and could cause different issues. 

You will find simple ways to fix some of your phone jack wiring concerns. Here are some tips for you to consider.

  1. Determine the main phone service cable within the box for your phone jack. Remove any other unused phone wires or cables. 
  2. Check the wiring connections of your phone jack. 
  3. These telephone wires are extremely small. One of the things you need to ensure is that the various colors of wires don’t touch one another. If so, it will result in numerous problems. 

How do you test telephone wire with a multimeter? 

Would you like your phone to work properly? Then it must be an independent circuit that doesn’t touch any other phone lines. If one phone line comes in contact with other lines, both of those lines will stop working accordingly.

What can you do to understand if your phone lines are touching? One way you can do that is by performing a continuity test with the help of your digital multimeter. Below are the steps you need to follow when testing a digital multimeter. Make sure you follow them properly, so you get the proper readings.

  • Remove any wires or cables that are connected to your telephone jack. For you to test the lines, it must be open as well. Always keep that in mind.  Find the NID for your phone service. Oftentimes, you can find it by locating the Telephone Network Interface print on the device. That box is where the phone lines link to the wiring loop of the telephone company. 

Feel free to get in touch with your telephone service provider in case you can’t locate it. They will give you the exact location of it. 

  • Remove the screws specified with “Customer Access” on your NID. You can use a screwdriver during this process. 
  • For the next step, remove the phone lines you like to test from its NID test jacks. Keep in mind that your phone lines will be totally open and ready for some testing after it’s completely disconnected.

Wait for a few minutes with the phone lines disconnected before you start proceeding. Doing this step will enable any electricity in the lines to evaporate. 

  • This is where things get really exciting. Grab your multimeter or DMM and set it to continuity mode, which is often marked by a symbol that looks like a sound wave. If you’re still in doubt, you can refer to your multimeter manual. 
  • Connect the tips of the lead of your multimeter together. If your meter is working correctly, a reading will pop up on display and will produce a beeping sound. 
  • For the next step, attach one of the leads of your multimeter to one phone wire and place the second lead to another phone wire. Bear in mind that your phone lines aren’t touching if your DMM doesn’t find any continuity. If it really doesn’t, your phone lines are touching somewhere and won’t work appropriately. 
  • Do the same time for each pair of phone wires. You will understand later which phone lines work and which wires do not after every pair has been tested with a digital multimeter. 

Final Thoughts

There’s no doubt that using telephone wires guarantees safety. Those are very simple to spread whenever necessary without the danger and risk of current shocks. On top of that, they are extremely durable and flexible and do not get damaged easily if entangled or twisted.

It’s worth mentioning as well that telephone wires are waterproof and so a safe alternative against other wires. We hope you find this post educational and enlightening at the same time.

So, the next time you encounter any problems with your telephone wires, feel free to check out this article again and learn how you can test it with a digital multimeter. 

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