Wiring installation and testing skills: bare wire Testing

The number of IP devices running on twisted pair wires is constantly increasing. You may think that two or more load power supplies and/or wires carrying low-speed signals in one sheath are based on bare wires) the simple test device is about to expire. A sample survey on the cabling and installation industry shows that the bare wire installation business may grow when the distributed audio, security, room control, and automatic operating system are used more widely. This article describes some common bare wire tests and tools that can be used for these tests.
Verify peer connectivity
Connectivity testing is one of the most basic test items for bare wires. It is used to search for continuous paths that run through each wire. During Connectivity testing, you can use a resistance-based multimeter to short the end of the wire to ensure the complete loop. When connecting a device like a speaker, you may need to test the resistance coefficient. When connecting to a security device, you may need to test the switch status. Many multimeter, such as fluke multimeter, are used to test switching conditions with closed circuit sound. This basic test can also be completed by many types of inductive audio generators, such as the MicroNetBlink of fluke network.™. This audio generator is equipped with a simple LED display that makes general Connectivity testing easy.
Polarity Test
Similar to connectivity tests, polarity tests are performed. A multimeter is usually used for Polarity testing, but an inductive audio generator with this function can also easily complete this test. The MicroNetBlink of fluke network can clearly display polarity through color LED lights. In general, low voltage polarity tests are mainly used for power supplies or signal lines of telephone cables and security surveillance cameras.
Length Measurement
Distance to short-circuit or open-circuit points is an important information for fault detection, and is also an important information for raw material management and the calculation of fees by the installer. The length can be measured electronically in three ways. The first method is to short the two wires together, then measure the resistance and convert the measured value to the length. Unfortunately, this method requires a transient cable, so it is rarely used.
You can also measure the length by capacitance. Just like a resistor, the capacitance between two wires varies depending on the length. The advantage of measuring the length by capacitance is that you do not have to pin the two wires together. Fluke network's 620 LAN cable tester, NetTool network multimeter, LinkRunner Link Channel, and other products can use capacitors to measure the length of the cable.
The third method is the use of time-domain reflection TDR technology, which is similar to the use of radio wave detectors to test copper wires. Send the radio waves downward to the cable. When an open or short circuit is encountered between the wires, the radio waves will be reflected back. The length of the cable can be obtained by recording the time when the radio waves are sent and returned. The transmission time varies depending on the transmission rate constant of different types of cables. This constant is usually labeled on the cable box, but a reasonable constant can be calculated using the TDR of the cable reference length. Microbench Pro cable tester, DSP-4300 and OMNIscanner 2 digital cable analyzer and other products have TDR function.
Fault Detection and raw material management
The basic management of raw materials is a daily task. At the beginning of each business day, you must check the length of cables in the cable box to be used or on the cable axis. If you use a TDR or capacitive tester, you do not need to short the end of the cable. Write down the value and confirm that it is sufficient for the length of the required cable. At the end of a day's work, check the length of the cable in the wire box or on the wire axis again, and subtract the length from the number measured before the start of work, that is, the length of the cable used on this day.
Another example of Length Testing is to conduct fault detection before the end of the work. If you suddenly find that a short circuit exists within 10 meters when using TDR for wiring connectivity detection, but in your records, the link should be 50 meters long. This may be because the installation staff of the dry wall just happened to pin the nail to a certain point, and you may find that the short-circuit position and repair of its twisted pair cable are different, you need to replace the cable ).
Locate cable faults using audio generators and probes
How can you find the nail point on the cable? Does your TDR show that it is 10 feet away? You can use an inductive audio generator and probe such as a MicroNetBlink Kit of fluke networks for testing. Connect the audio generator to two wires and power them on. The cable sends a signal passing through the dry wall, and then uses the fluke network's MicroProbe audio probe to capture the 1000Hz signal, and convert it into an audio signal to quickly find the fault point.
Capturing such a signal is both beneficial and unfavorable for your work. You can use this signal to detect the wires in the wall, but if you encounter two parallel cables, you may have trouble. One of the unpowered cables may capture the signal of the powered cables, making it difficult for you to identify them. To avoid this problem, you need to leave a certain distance between the two bare wires during cabling. In addition, cables collect the noise from fluorescent lights or running machines. To ensure the speed of inspection, minimize the noise.
The above are some basic tools and testing methods you need to use when installing bare wires. For your work, they not only mean simple connectivity tests, but also help you reduce the time for fault detection and troubleshooting.