OSP Expert: Don McCarty

The unknowns that make fault locating in sections of buried telephone plant difficult.


Most bad sections of buried copper plant are a slam dunk to fix, especially when the well-equipped and well-trained technicians are given time to find and repair the root cause of section failure. These buried sections are usually in the distribution plant, and they are usually 25-pair or 50-pair PIC cables. They have failed because of sheath damage, splice or encapsulation failure. It is usually fresh trouble if there are no prior complaints from the customer. First, when trouble-shooting a bad cable pair, the skilled technician using a multifunction test set that includes a resistance fault locator (RFL), an open…

Electric Fence Interference


I received a question from a field technician about electric fence interference. He shared that he had a case of trouble that included noise on the telephone circuit emanating from an electric fence in the area. He said that the line is free of DC type faults. He was wondering if it could be a grounding issue? In some 50+ years in the telephone business, I have dealt with the effect of electric fences on voice grade circuits, bandwidth circuits, and even rarely, circuits where the customer is fiber fed. Once the cause of disrupted service is proven to be…

A Hitch in the IoT


In 2019 I see the IoT expanding at an alarming rate, and I project that the infrastructure will fail to keep up with the demand. More things are communicating with more things over the wired infrastructure, the wireless infrastructure, fiber infrastructure, and, yes, the coaxial cable infrastructure. If there is a disruption of any of the infrastructures, then the IoT is affected. Any down time on any of the 4 structures will have both immediate and long-term effects on the IoT.  Concerns Network reliability is all important. My concerns are many.  My first concern is the oldest copper infrastructure which…

Using the earth-gradient test set when fault locating in buried plant


Around 1976, a fine gentleman by the name of Tom Lathrop, then with Bell Labs, invented the earth-gradient method of fault locating. Using a transmitter, an earth contact frame, and a receiver, transmitted voltage differences are detected and shield-to-earth or conductor-to-earth faults are exactly pinpointed in buried plant. Two test sets were manufactured by Western Electric, one for cables, one for drops. And finally, the difficult world of buried fault-locating was made simple. Several manufacturers build similar devices, and they all use the same principle as Tom’s sets. Today’s earth-gradient test sets work on any cable or drop that is…

Troubleshooting the Copper Network


When Test Sets Do Not Perform to Expectations — Field technicians have a multitude of test equipment that is used to identify and locate faults in the copper network. Many of the test sets have multi-function features. If the fault or faults in the cable are resistive in nature, such as unwanted shorted and grounded cable pairs or crossed battery from other cable pairs in the same compliment, the test set has a resistive fault locate function (RFL) and a Time Domain Reflectometer (TDR) function to help you locate these problems. If the fault or faults in the cable are…

Repair of Your Wounded Copper Infrastructure


In an earlier column we discussed the proactive process of finding single pair faults in the copper infrastructure rather than moving the customer to another cable pair to restore service. This proactive approach of finding and fixing single pair faults will resolve problems in 95% or more of your copper infrastructure customers, and quickly gets them back in service. Additionally, adhering to this process can support identifying other potential pedestal and terminal problems that can be repaired before customer service is affected. The other 5% of service interruptions occur in bad sections of cable, both aerial and buried, in the copper…

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