Record Keeping of Open Wire Facilities

Open Wire Exchange and Toll Facilities’ Record Keeping



Complicated circuit arrangements as shown above in the Nevada Transcontinental Toll Lead required accurate and up-to-date records.

Occasionally, I have been asked how the various telephone companies and cooperatives maintained proper records of completed open wire exchange and toll circuit leads.  Once the design perameters were determined and the best physical designs physically constructed, the finished product stood for years as a substantial investment allowing telephone traffic to traverse the multitude of channels available.


Naturally–and essentially--proper records were demanded of these facilities so continued maintenance, storm-damage repair, and rehabilitation of facilities might continue through their expected life-expectancy.  It was expected over the years, various circuits might be added and removed; drops and extra exchange arms mounted, equipment terminals, protectors, filters and other items installed or de-installed as owners required.


Continued maintenance of proper records made successful operation of an open wire lead were essential.  These records were kept at the Wire Chief’s wire center offices.  Here, readily accessed by engineering, maintenance and accounting personnel, they provided a revealing look at the grand investment which was open wire plant construction.


Telephone Company and transportation company records were called various things.  The Bell Companies and GTE Organizations called them MPLRs, or literally Mechanized Pole Line Records.  These MPLRs were large graphics displayed on 24″ x 24″ or of similar sized paper, detailing maps of various locales, cities, rural sections and other sites where the open wire exchange and toll leads lay.  Their symbolic portrayal often followed major and minor highways between towns; the most accessible routing possible for maintenance forces’ access.  When the telephone industry moved into aerial cable and later, underground and buried facilities, these MPLRs did not change name, but simply incorporated the multi-pair cables, their associated loading coils, repeaters and terminals, along with whatever working open wire yet existed to form part of the owner’s general investment in outside plant.  As these aerial cable and buried cable assets grew, and open wire retired, the old MPLR term remained.  Thus demonstrating the importance of how  the telephone industry’s historical heritage of open wire might leave in its wake.


In order for facilities to be improved, it was essential that these records be consistently updated so local loop and transmission engineering personnel could turn to them to rely on an accurate portrayal of existing plant.  Then, a future appraisal could be accurately done as rebuilds and rehabs were necessitated.


Let’s Look at the Open Wire Circuit Diagrams as Toll Facilities

In the early days, large black leather “bank accounting-style” binders formed the top and bottom covers of these massively continuous record volumes.  These approximately 8 1/2 x 17″ sized pages recorded pole-by-pole placement of a toll lead between towns (we’ll cover “in-town” facilities later).  Around 75 to 100 pages would fill an average route between those two covers.  On each page, from the beginning of the route to the end, topography of parallel highways, intersecting roads and farm driveways, creeks, bridges, trees, and other objects were noted. 


The field notes from which the earlier designers of the line compiled in order to plan the lead were converted into hand-drawn drafting sheets by the clerks in the telephone transmission engineering department, then recorded for formal inclusion into the MPLRs after they had been approved by superiors.


Cable diagrams were based solely on the pair-assignment of each “Quad” of the cable, whether aerial, buried or underground.  Open wire was based on crossarm pin placement and physical location of each carrier, phantomed or non-phantomed pair.  Doubtless, carrier system assignments on open wire leads demanded very accurate records of each pole line.


A synthesization of a toll aerial wire record based upon various companies’ formats. Note the early days–prior to computers–pencil strike-throughs meant pair assignment revisions.

Let’s look at some possible examples how open wire was recorded.  In the days prior to computer posting and easy correction, all record keeping was done on paper.  Typewriters and pencil markings were made to a “copy” of the original drawing laid across the permanent geographic setting.  A formal and accepted pole line diagram was drawn on the master and then a lightweight carbon copy vellum applied to each page on top.  This could offer the opportunity to make possible changes to various circuits as they were modified over time.


The toll central office in one town initiated the line’s route.  At the final page of the volume was the terminal structure or terminal/junction pole where the lead ended at the next town.  From there, an aerial or buried cable extended to the central office there.  While the frame was not noted in the C. O., the entering and exiting toll entrance cable[s] with each quad identified pairs were noted.  The length and guages (if differed within a single sheath–and earlier cable did have this older characteristic) was noted.  If repeaters and loading coils were required to be placed as the cable wound around town blocks as it drew closer to the open wire terminal structure and central office, these were noted.  The distances and spacing between terminals marked.  Bores, conduit, streets, driveways, creeks and other landmarks were also accurately drawn in along its winding path.


Once the buried or aerial cable had reached the open wire toll terminal structure at the edge of town from the central office, the diagrams took on a decidedly different portrayal than had the earlier cable facilities.   This conversion of cable to open wire was a significant physical change for which specialized equipment had to be installed to make the transition possible.   Hence, below I’ve listed many of the important features which characterized the open wire lead’s new incarnation shown on the MPLR plats which followed:


Pin positions

Crossarms showing both occupied and unoccupied pins (1st to last arm)

Pin spacing (if they were irregular, say beyond or within 24″ clearances)

Wire type: copper, copper coated steel, aluminum covered steel, etc.

Type of insulators used

Transposition bracket types applied to the system

Circuit frequency

Filters and carrier transfer sets

Special protection equipment sites

Junctions of open wire and other cables

All toll stations and their junctions

All changes in the line needed to be dated and recorded at location

All poles needed to be identified with numbers or alphabetical combinations

Changes in the size, kind and position of wires

Entrance cable terminals

Political boundaries and tax districts

Repeater stations


Geographic aspects rarely changed along a lead’s route.  However, there were highway projects which might add lanes and require bar ditches to be moved and property lines modified.  This in turn, required the line to be moved physically or rebuilt as either another open wire lead or designers took the opportunity to convert open wire to aerial or buried cable.  However, most information was permanently applied to the MPLRs’ master sheets.  When a lead did change composition, here are some of the changes expected during the life of the line:


Voice frequency assignments

Telegraph and alarm assignments

Carrier system assignments

Junction connections

Circuit order number and date of install


Without exception, telephone utilities with whom I worked, required the time (date) and work order number.  This identified the time when changes had last been made to the equipment or line placement.  These accounted for placement changes, removals or transfers of poles, the lead’s modification or reconductoring.  Foreign circuits and pole lines (other telephone companies, railway communications leads and electric power facility lines) were also noted on each plat.  Each sheet usually carried a note (sometimes on a separate page) incorporating features of newly installed specialized equipment.  This inset was included so Installation and Maintenance (I&M) people could access the needed technical bulletins and wiring diagrams of foreign equipment.


Let’s say there was, on a railway circuit, a Lynch Filter or Lenkurt Choke or Short Circuit Relay Protector applied to a particular location.  Naturally, if a serial number was noted on the sheet, one might find the contents of the major components inside the cases, and a schematic drawing enlisted so repair could comprehend interior arrangements of wiring.

Here we see how pole equipment was identified in a case similar to the Tyndall-Mitchell/Tyndall-Wagner, South Dakota lead and junction/terminal pole. I’ve amalgamated various formats to portray typical companies’ record styles.

Keeping Track of Transpositions in the Lead

When it came to transposition systems’ records, telehone and railway company needs were demanding in this respect as well.  A small error by omitting one drop or phantom bracket could wreck havoc on the satisfactory operation of the entire system, so both voice and carrier frequency lines demanded a high degree of record accuracy.


Not only was this information important for engineering, but if storm-related damages occurred, the I&M personnel could have a complete design knowledge of the system.  Furthermore, the Testboard Manager necessitated good records so that he (usually in the early days it was male dominated) could target the location of trouble.


Recording transpositions along a toll line on a paper trail could be very complex.    Indeed, the amount of information and the paper trail of paper to maintain these records depended upon the number of circuits and arms involved in the length of the line.  On a sixty wire line–four ten-pins of toll and two of exchange circuits–32 intervals would be drawn on the master drawings.


The permanent records of the transpositions, like the other details previously noted, were part of the master drawing set.  Laying on top of these pages were the opaque vellum sheets where pole numbers, section and sheet numbers could be noted.  Since poles might be replaced or removed, this nomenclature was omitted from the master design drawing. 

Charting of how transpositions inserted in a typical lead were recorded. Note the “P” brackets or Phantom Groups transposed. “D” stood for Drop Bracket configuration.

I hope this brief review gives the reader a better understanding of how records were kept on open wire facilities.  By converging these various record formats of numerous companies in our examples above, clearly most forms were very similar in nature.


Most interesting in my work was the significant degree of pictorial and geographic illustration in order to establish and maintain these vital records.  Buried cable placement was even more exacting, than open wire, where records were concerned.  Open wire danced along the landscape, dodged this obstacle, then the next tree, climbed a hill, then jumped a long-span creek occasionally.  However, when buried cable spurted below the ground and across the landscape (and later buried fiber), the need for record keeping and advanced computer-drafted third-generation versions of MPLRs was paramount.  Here, boring, pushing pipe, placing conduit, manholes and handholes, running buried drops, or fighting for space in congested ductwork, complicated matters acutely.  Costs mounted in such intricate construction processes.  Indeed, when trouble occurred on open wire–as it occasionally did where storms and auto accidents impacted it–trouble was easy to spot and generally promptly accessed by service personnel and successfully restored.  Buried cable . . . opened up a new can of worms . . . where trouble was less likely to be located quickly and whose costly repairs were done with significant complications.

Here, repairs on buried cable commands the attention of telephone personnel. Photo credit: Tri-County Telephone Association.