What is a Network Cable Tester?

Jennifer Voight

When connected to an Ethernet cable, a network cable tester tells if the cable is capable of carrying an Ethernet signal. If the cable carries the signal, this indicates that all the circuits are closed, meaning that electric current can move unimpeded through the wires, and that there are no short circuits, or unwanted connections, in the wire. Network cable testers vary in complexity and price, but a basic tester consists of a source of electrical current, a measuring device that shows if the cable is good, and a connection between the two, usually the cable itself.

Network cable testers are used to tell if an Ethernet cable is capable of carrying a signal.
Network cable testers are used to tell if an Ethernet cable is capable of carrying a signal.

Computer networks use Ethernet cables to allow computers in the network to “talk” to each other. An Ethernet cable has eight wires that are arranged in four pairs. For current to flow correctly, the wire pairs must be connected in the proper order.

Network cable testers are frequently used to tell whether a patch cable will work before it is connected.
Network cable testers are frequently used to tell whether a patch cable will work before it is connected.

A network cable tester can identify if the wires are paired correctly. It can also show if there is a break in the insulation, a situation which allows crosstalk between two wires that should not be connected. The tester can also tell whether the cable has the proper level of resistance.

Computer use Ethernet cables to network and communicate with one another.
Computer use Ethernet cables to network and communicate with one another.

If a network isn’t working correctly, the problem is frequently user error or other problems. It will rarely be a faulty cable. A network cable tester is more frequently used to tell whether a patch cable will work before it is connected. The cabling should first be examined visually to identify any obvious problems. If everything looks correct, a network cable testing device may then be used.

A network cable tester can be a simple apparatus that merely identifies whether current flows through the cable, or it may be a professional-level, complex device that gives additional information that helps identify the problem. Professional-level network cable testers may not only tell if an open circuit exists, but may identify where the break is located. Some also identify the gauge of wire used and can generate their own signal to test for interference.

Basic network cable testers can test for simple connectivity issues but may not identify other problems that cause the cable to malfunction. Cabling may not work when it is near a source of interference or if the cable is too long. Intermittent faults may develop that do not show up when the cable is tested. Sometimes the problem is not sustained long enough to show up on the tester.

Ethernet cables are usually used to establish physical connections to routers.
Ethernet cables are usually used to establish physical connections to routers.

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Discussion Comments


I use cable prowler made by T3innovations. It works great when checking your cables.


Even though I don't make ethernet network cable connections very often, I do have to do it sometimes for my house and for my business. Because of this need I have found that the low and of network cable testers are actually very effective for my use. You can purchase one of these on the Internet at a relatively cheap amount. I recommend this for anyone who is planning on doing network cable installation even if it is on a small scale.

I recently had the opportunity to try a higher into network cable tester and honestly, I was not impressed. The device that costs several hundred dollars did the exact same job that I needed for a device that I paid a mere $40 for. Not only did my device cost significantly less than the expensive professional grade device, it actually came with its creepers and connection heads for RJ-45 ethernet connections. For anyone who's ever purchased these additional accessories they will realize that actually is not a cheap purchase in the long run. The best way to buy these kind of accessories in bulk that many people will never use that many RJ-45 ethernet connections. Because it was included, I was able to save valuable money that I need to help run my household and business.


Often people miss the fact that there are many different types of network cable testers available on the market technicians and installers. One of the less common, but more important, kind of network cable tester is a fiber optic cable tester. These highly advanced and a very expensive testers must be absolutely accurate when making these expensive connections. Hours of special training in months of education must go into a technician that is performing fiber optic network connections. One of the highest paying jobs in network cable installation is actually the person who polishes the end of fiber optic cables. Because the glass that transmits the light signals and fiber optics must be absolutely perfect, it is extremely important that the tests performed on these kind of connections are accurate.

For this reason you will not find fiber optic network cable testers available to most consumers. These devices cost thousands of dollars and are only usually owned by large communication companies or companies that specifically contract in fiber-optic network communication installations.


@MrPolitic99, You are correct in your statement that these kinds of network cable testers are absolute time savers for installers and technicians. If you have ever tried crimping the end of a category five or another type of ethernet connection, specifically RJ-45 or RJ 11 then you will understand the frustration that can come along with making these types of connections. Inside of category five ethernet cabling are four twisted pairs of wires. This means that the wires inside of them are very small. Because of their size it is very difficult to align the proper cable pairs into the connecting head and Karen Bates with a secure connection. Often for the amateur that doesn't do this very often, it can take several attempts to make sure that the connection is done properly.

If the amateur does not have a network cable tester this means that they must manually test the connection by using the computer which can take much longer than simple continuity tests on the cable. These devices are truly timesavers as any technician can tell you and I recommend for any amateur that they look into the cheaper models of network testers if it is something that they do more than a few times a year.


People who were not in the information technology industry might not truly appreciate what it is that a cable tester is actually capable of. It is not that the type of device a network cable tester is so complicated to understand. But the time-saving ability that these testers have is comparable to none.

By allowing for network cable connections to be tested via a device, technicians and installers that develop and implement very complicated network systems are able to save a great deal of time and effort. Ensuring that these connections are completely stable and properly connected means that they will spend less time troubleshooting issues later in the future. This type of sure fire installations mean that you as a consumer will have less downtime on your end.

As the author mentions, there are many different types of cable testers for network administrators and installers. The most common of these network cable testers are ethernet-based. These ethernet cable testers will often have several modes of testing the cables and connections. Because Ethernet is the most commonly used type of communication system for computers, ethernet network cable testers are the most common type of testers you will find inside of the technicians toolkit.

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