Opinion: How to reduce pole top fires in Australia

Opinion: How to reduce pole top fires in Australia

Several pole top fires incidents have been recorded in Australia. ABC news reported on 4 February, 2020 that Perth power outages affect almost 50,000 properties due to electrical sparking and pole top fires.

Thousands faced blackouts for the same reason on 3 January, 2019. The Black Saturday fires in 2009 were also caused by poles and power asset failures.

Power outages are a major issue that affect power utilities, and customer and malfunctioned power poles are a major reason of such outages.

Wooden poles are substantially engaged in Australia for power distribution and transmission network reason being their low cost, high durability and environmentally friendly nature.

Moreover, insulators are used to provide support and insulation to energised high voltage current-carrying conductors. Ceramic insulators on various voltage levels have been significantly used in Australia and worldwide.

Malfunctioning could be either because of timber decay by biological attacks and/or pole top fires. Electrical insulators’ failure is a leading source of ignition of wooden poles from the top.

Pole top fires occur due to the presence of pollution, salt particles and dust on the surface of insulators. Under humid and rainy conditions, the pollution layer becomes electrically conductive and starts a high amount of fault current and arcing.

This activity starts fire at the junction of wood and metallic section on the cross arm. On a serious note, it can drag down the energized conductor on ground and trigger spark in the dry vegetation present on the ground.

This may also one of the major causes of bushfire’s ignition.

How can we mitigate pole top fires and power outages?

A report entitled “In depth Exploration into the State of Victoria’s Power Assets” suggested that poles fire incidents are definitely increasing due to old style insulators. The continuous build up dirt on old insulators specially in summer caused power outages. Low pace of condition monitoring and replacement of insulators is another prime reason.

Power utilities should carry out a regular condition monitoring of the power lines in high risk areas. Insulators conduct high amount of leakage current in the presence of wet pollution.

Therefore, insulators should be cleansed with water on a serious level in order to avoid build of huge leakage current. Insulators with large leakage current path will also maintain the resistance to flow current. Replacing pin type insulators with post or low leakage current polymeric insulators could be a potential solution.

Moreover, ceramic or glass insulators should be coated with highly hydrophobic RTV silicone rubber coatings. This will reduce the negative impact of pollution and assist in stopping electrical sparking.

The timber cross arms where insulators sit should be replaced with steel or some highly flame retardant and electrically insulating composite materials.

The above recommendations will significantly reduce the chances of pole top fires and further research is also necessary to develop a cost-effective solution of this electrical failure of power lines.

Muhammad Tariq Nazir has a PhD in high-voltage outdoor power line insulation and works as a Research Fellow at UNSW on CRC-Projects of Flame Security International. You can follow Tariq on LinkedIn, Facebook and Twitter.