Powerlines: a problem that should be buried

Powerlines: a problem that should be buried

12 June 2013

published by www.whatech.com

Australia –Above ground power lines are a menace, and they’re ugly. They are the cause of many bushfires and the poles that hold them up have a nasty habit of leaping out and attacking unsuspecting motor vehicles, with often tragic consequences. There have been many calls for mass burial, but unfortunately the cost has proved prohibitive.

And did I mention that the poles have a limited life span and must be replaced regularly, at considerable expense? The Canberra Times reported recently that: “Spending millions of dollars a year replacing timber power poles [in the ACT] appears likely to continue because it would cost … $15,000 to $20,000 per property to put existing power and telecommunications wires underground.” It added that: “Running all of the ACT’s power underground would mean converting overhead power at about 100,000 properties at a cost of $1.5 billion to $2 billion.”

Meanwhile, The Canberra Times said, local energy company ActewAGL is spending around $5 million per year replacing old power poles with new ones, at about $10,000 a pop. The paper said that ActewAGL was looking at conducting a pilot undergrounding project and it quoted a company executive saying that the project would go ahead only if home owners were willing to contribute to the costs (many power poles in the ACT are at the bottom of people’s gardens).

However the problem of powerline ugliness pales against the potential fire hazard. According to a presentation made to a 2012 forum on bushfires in Victoria, powerlines contribute to more than 200 bushfires in the state every year and were a significant contributor the 1983 “Ash Wednesday” bushfires and the 2009 “Black Saturday” bushfires.

The Royal Commission held in the wake of that catastrophe recommended that all single wire earth return (SWER) overhead powerlines in the highest bushfire risk areas be replaced with either underground or bundled overhead cable within 10 years.

(With SWER cables the circuit is completed via the earth so there is always the potential for sparking between the cable and the ground. Bundled cable contains all the wires needed to complete a circuit, bound tightly together and insulated, greatly reducing the risk of a short circuit.)

According to the presentation, the Victorian Labor Government of the day rejected the Royal Commission’s recommendation on the grounds of cost, estimated at $60 billion.

Less headline-making but also extremely damaging is the contribution of power poles to the road toll. The NSW Government, according to the presentation, has estimated the cost to the state of car/power pole collisions at $178 million annually. And it is not just motor vehicles that fall foul of powerlines. The Civil Aviation Authority has estimated that they contribute to 25 percent of all low-flying aeroplane accidents. Hot air balloons have also fallen foul of powerlines on a number of occasions, with sometimes fatal consequences.

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