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Why should trees be trimmed?

Are your trees too close to powerlines?

Trees or branches touching powerlines are one of the main causes of power interruptions. They may also cause fires and/or other serious accidents. Horizon Power encourages the planting of the right tree in the right place. Unfortunately, many trees are planted, or have naturally grown, too close to powerlines and need to be trimmed. Failing to trim your trees can cause power failures, bush fires and serious accidents. In unusual circumstances, trees may even become ‘live’ when they come into contact with powerlines, posing a serious safety risk.

When do trees need to be trimmed?

Trees must be trimmed if they are too close to powerlines. In the north of Western Australia, trees should also be trimmed before the summer cyclone season (NovemberApril). Trees in the Mid West and southern parts of the State should be trimmed before winter. Horizon Power regularly conducts inspections of powerlines to identify where vegetation is growing too close. The following diagram shows the minimum clearance zone. As a general rule, trees should be no closer than three metres to powerlines.


Which trees am I responsible for?

It is the resident’s responsibility to trim trees on private property, even if they are not the home owner. You may want to check if this is covered in your rental agreement. Horizon Power works with local councils to carry out vegetation management programs on urban street verges and road reserves. As a guide, the trees coloured orange in the diagram below are the responsibility of the occupier of Property A; those coloured green are the responsibility of the occupier of Property B. The tree planted on the verge (blue coloured tree) is the responsibility of the local council.

Who should trim trees?

If the trees at your home need to be trimmed, Horizon Power strongly recommends you hire a professional tree contractor as they have the correct training and experience to carry out the work. Check the Yellow Pages for local tree trimming contractors or visit