OSP Expert: Don McCarty

High Voltage Transmission Lines Over a CO/Hut

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I recently received an email from Aaron, a manager of an independent telephone company, discussing the effect of high voltage lines on telephone equipment. He stated that a power transmission company is proposing to build a transmission line adjacent to one of his existing telephone buildings. From the proposal drawings it appears the lines will be within 100’ of the building, and could possibly go directly over the building. It is an unmanned building, but they have copper and fiber equipment and distribution at this location. He asked me if I foresee problems from electromagnetic interference and, if so, is…

Moisture Diffusion in Underground Pulp Cable Networks

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During a phone call, a cable maintenance supervisor from a large metropolitan area described a cable maintenance problem he had been recently encountering when qualifying pulp cable pairs for power pairs. When testing any cable pairs for potential power pairs, the pair must test less than 10VAC tip to ring, tip to ground, and less than 3VDC tip to ring, tip to ground, and ring to ground. The insulation resistance must test greater than 100 megohms tip to ring when applying 500VDC to the pair with an electrical insulation test set, and greater than tip and ring to ground when…

More on the Resistance Bridge

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In last month’s column, Tim, a skilled field tech, stated: Maybe I missed it, but I’ve never seen a good column on the resistance bridge feature. It is the best time-saver there is when used properly, especially when using it in the field by yourself. It can help you get a good idea where the trouble is as opposed to having to be dead wrong when digging up a street or someone’s front yard. Any tricks and tips would be appreciated. Thank you, Tim Segada In the June column I explained the basics of electronic reference, and Tim stated that…

Fault Locating the Copper Infrastructure With a Multi-Function Test Set

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I recently received an email from a quality cable maintenance technician. He stated the following: Maybe I missed it, but I’ve never seen a good column on the resistance bridge feature. It is the best time saver there is when used properly, especially when using it in the field by yourself. It can help you get a good idea where the trouble is as opposed to having to be dead wrong when digging up a street or someone’s front yard. Any tricks and tips would be appreciated. Thank you, Tim Segada The resistance fault locating feature (RFL) in the multi-function…

Finding Cable Trouble With a Multi-Function Test Set

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We constantly hear in the field that a test set is not performing its advertised task. “My resistance bridge missed that trouble by 75 feet.” “This open meter measured short or long.” “The TDR indicated the fault at the wrong footage.” These test sets measure footage based on the test set design engineer’s input when he built the test set, and the field technician’s input when he is using the test set. Garbage in, garbage out, folks. When trouble is isolated to a section, and the technician decides to go after it, a conceptual picture must be built to analyze…

Even Badly Neglected Copper Has Life Left!

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The following opening paragraphs are contributed by Chuck Blume, someone who’s been in the industry for a very long time, starting as a cable repairman and moving into selling and training on more types of equipment than we can name. Sometimes I feel I’m alone at the pulpit so I appreciate hearing my oft-preached messages coming from someone else! From Chuck: If you had told me in 1972 that by the mid-1980s I would be working in an electrically lit, air-conditioned/heated, and water-proof manhole (Controlled Environmental Vault), I would have thought you escaped from Area 51 in Nevada! And I…

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