Post And Telegraph Technicians Go Underground For Big Gable Job

Chronicle (Levin), 11 January 1949, Page 4

Post And Telegraph Technicians Go Underground For Big Gable Job

What really goes 011 under that eanopy just outside the Levin Post Office? Those strange subterranean activities of P. and T. workmen, who have been in occupation of that canopycovered manhole for sonle months now, has fascinated many passers-by. / They also fascinated a "Chronicle" reporter— so much so ' that yesterday he sought enlightenment from Mr. C. J. Warn, of Palmerston North, who is in charge of the operations. He learned that the workmen v/ere engaged in testing, replacing and adding to the cables which serve the district's telephone subscribers. Some of the cables, he was told, had been there for 20; years.

The biggest task; however, is the laying of additional cable to link with Levin's greatly expanded exchange. Mr. Warn said that the number of wires laid would be 'double that at present housed in the manhole, and he envisaged 12 months' work on the project. The distance to which the cables will be laid has also been increased, the intention now being to carry them to very near Ohau, instead of Kimberley Road as previously. Mr. Warn is foreman and instructor and he has four local men working for him. • To'be housed in that manhole in Oxford Street will be a cable made up of 2000 wires, or 1000 pairs, as the $ires are linked in pairs ,each pair representing one telephone. From the manhole, or, to give it a technical name, jointing chamber, will go a 600-pair cable to the railway station, a 200-pair cable to Weraroa Road and a '200-pair cable to North Oxford Street, all being branched from the main 1000-pair cable. Previously the distribution was smaller, and from a 600-pair cable In Queen Street East,. another jointing chamber, which previously housed a 200-pair cable to service that end of the borough, will now have a 400-pair cable. From the jointing chambers the cables are carried underground to certain points and are then brought out in 25-pair lots to overhead terminal boxes, which in turn lead ofi to the various houSes. It was the policy, said Mr. Warn, to take cables underground as much as possible. both from an economic point of view, as maintenance costs were accordingly lessened, and from a service viewpoint, as the subscriber was then less likely to suffer inconvenience through damage to the wires. A 1000-pair cable incidentally measures three inches in diame^er The other side of the story is to be found in a room off thtf post office exchange, where the cables are connected to the MD.F. (main distributing frame) in silk and cotton cables, and "jumpered" from there across to. the switch board,

where they are connected to the numbers. To return to the men in the jointing chamber, however .... During the laying, replacing and general inspection of the cables, ieach wire is cleaned, jointed and soldered into nosition, after whichthe joint is insulated. All joints are "plumb-wiped," a term abbreviated from "plumber's wipe" and • meaning assuring water tightness. This is most important apparently, as water penetrating the joints would cause considerable damage. To ensure that there are fio leaks in the finished cable, gas is pumped through. A cylinder with a clock, which registers the pressure, is used. When the clock registers 20 lbs of pressure, the cables are left from 24 to 28 hours. Just before Christmas, passersby might have observed an appliance, which looked uncommonly like a very lengthy pull-through, being used between manholes in Oxford Street. Mr. Wafn says that that was precisely what it was— a long rope with a chain or "Mandrill" . attachment, which, when pulled the 1 "duck lines" or Manason pipes, " which carry the ■cables, cleans them out thoroughly, removing any stones and other obstructions which might cut the cables. As the pipes have been , there for 20 years, this measure is necessary. The pull-through also locates places where the ends of pipes have sunk slightly, -and squares off any jagged edges or rusted parts. But what happens when a fault develops underground? Surely it must be a big task to find where the fault lies? Mr. Warn. had an anSwer for this question, tqo. He said that with instruments in use today it was possible to test the lines and discover with ease the exact location of any fault. .And while all this jointing work is going on under Oxford Street, is the subscriber on the line not inconvenienced? Mr.. Warn says no. The whole operation is being carried out without the subscriber be- , ing affected, in any way. The cutouts are of durations of only a sec - ond or two,.