DANGEROUS CALLING

Manawatu Standard, Volume LIV, Issue 295, 10 November 1934, Page 12

DANGEROUS CALLING

HIGH VOLTAGE LINES. _

REPAIRING LIVE WIRES

Work done by the Public Works Department, particularly that bn the Mangahao system, with reference briefly to its history, personnel and training, equipment and methods, Was discussed by Mr F. M. Doig, assistant electrical engineer for the department at Napier, in an address on live-wire maintenance of high tension transmission lines to the conference at Palmerston North yesterday of the North Wellington branch of the New Zealand Society of Civil Engineers. “Live-wire work in New Zealand,” he stated, “started in 1926, when an engineer who had been trained in the United States was loaned to the Public Works Department by the Tasmanian Government to 'instruct New Zealand linesmen in buzz-stick testing and live work generally. He trained a few men in both islands and further men were then instructed at Mangahao. Insulator testing was made a routine work, and annual tests have been made of all 110-kilowatt insulators in the system. Maintenance work was relaxed, but three years ago it was found impossible to do all the maintenance necessary during short shut-downs especially on the single 110 lc.v. lines to Wanganui and Masterton, so that line work was revived, and a fully equipped maintenance gang was organised and trained. “Live line workers should be good aloft, have great patience, a certain amount of ingenuity, an inherently careful nature and be essentially trustworthy. The man who is continuously, though subconsciously, nervous of the work, is better away from it. All liveline workers are trained as testers. The original men were trained experimentally for six weeks in replacing poles on live lines. Resuscitation practice is carried out once a month. Since dryness and cleanliness are essential to safety, great care is taken of testing sticks and ropes, and ground sheets are provided for any gear that rests on the ground. Sticks and ropes under test stood 75 k.v. per foot for five minutes and oil samples 21 inches long flashed over at about 114 k.v. per foot. “Feeling out a stick is done by presenting the stick to a live wire, end on, and by running one hand along the stick towards the line, with the palm very close to, but not touching, the stick. If the stick is in poor condition a peculiar fuzziness or vibration is felt, somewhat similar to that felt if the fingers are lightly placed on an electric iron when it is heated up. If the stick is in perfect condition and the weather is good—that is, when the atmosphere is dry—fuzziness should not be noticeable within three feet of a 110 k.v. line. Knowing the stick to be good, the state of the atmosphere, as regards safety, may be gauged by the distance down the stick that the fuzziness extends, and this is used as a standard test when working. The sticks used to test insulators are made of Southland-beech. “During the last 14 months, on the single spur lino from Woodville to Masterton, 852 suspension strings were replaced with tested units, and 242 strain strings were renewed. Fifty-one poles below the required factor ot safety were renewed. Thirty-two unsafe cross-arms were replaced and 270 poles were either lowered or recut. lo do this work, all of which was necessary to bring the lines to a condition expected after a major overhaul would have meant, by dead work, shutdowns totalling at least 250 hours, even if the number of men had been doubled. The two areas served by this line have therefore been saved a long series of very annoying interruptions to supply, apart from accidental interruptions due to breakdowns.