. . . And why is it relevant in today’s high speed world?
“Open wire,” as opposed to “cable,” is defined as a system of bare or insulated conductor (line wire) attached to insulators of glass or porcelain by means of a tie wire, the dielectric screwed onto wooden or steel pins, which are then attached to crossarms (or brackets) configured in standardized spacing designs, with the assembly bolted to poles, braced accordingly and poles placed in the ground or anchored to a reinforced surface. The conductors (lines) are then suspended between poles to make up a complete circuit between consumer and central offices or an intermediate switching point.
But aerial “open wire” was not merely the feat of stringing endless miles of strung wire pole after pole after pole without meaning; it also incorporated all the electronics, all the electrical protection and terminals which made it function properly. H-fixtures and special structures were not placed for decoration, but to protect its vital messages transmitted through it from the worst that weather might throw at it.
Open wire was also a mindset of the people who worked with it; designed and engineered the promise of long distance communications for over a century. It incorporated the safety practices, the wire center administration, the crafts of those who constructed and maintained it, as well as the subscribers who called upon this technology to cement communities into one vast net of communications intimacy.
Aerial wire for electrical communications was used as early as 1838 in Germany, with Britain having demonstrated its use for telegraph experimentation in 1840. In the United States, Samuel F. B. Morse, contracted the construction of an experimental aerial circuit between Washington, D. C. and Baltimore, Maryland in 1844. This was the first practical demonstration of the telegraph technology. Earlier attempts at burying lines was not successful and these pioneers resourcefully adapted aerial wire as the first applicable medium of communications.
The practice today of leasing “dark fiber” with optical fiber transmission systems (FOTS) began with the leasing of open wire pairs to various companies by AT&T as well as railway transportation companies. Typically, the lower arm pairs were leased to Western Union, Postal Telegraph, Overland Telegraph and other similar carriers.
Today’s OW or “Order Wire” plug-in for Optical Line Repeater and Optical Line Terminating Multiplex equipment harkened back to the old traditional open wire days when an “order wire” was just that: a party line connected to open wire test stations along the transcontinental and other major toll leads of open wire to “order” facility checks, equipment installations and removals.
There are many other traditions which have deep significance to the open wire era which today have been lost, but remain today in our modern symbology.
Open wire is repleate with establishing conventions which have exceeded their aerial wire yesteryear traditions. Today, I wonder how many telecom techs know about how these lingering terms came to be?
When American telephone pioneers began to expand their systems after the practical demonstration of the device in 1876, open wire was the accepted and tried medium. Aerial multi-pair cable was also attempted initially, but the proper theory vs. actual practice, delayed its use until later. Many unresolved, technical problems prevented multi-pair aerial, buried and underground cable until years after the first open wire lines were an established (and successful) medium.
So . . . you see? Open wire still has relevance today!