
The Sky
Understanding Vegetation Clearance Above Powerlines
In both rural and some urban areas of Victoria, the Code requires that the space above powerlines be clear of any vegetation, a policy known as “Clear to the Sky.” This clearance involves two specific requirements: the “applicable distance” and the “sway clearance.”
The applicable distance is set at 2 metres. This has been a part of the Code since its inception, and all vegetation within 2 metres of a line drawn vertically from the conductor must be removed, along with an additional allowance for regrowth.
The sway clearance is added to account for wind-induced movement of the powerlines. Distribution companies have calculated how much sway various types of conductors experience, and this distance is added to the applicable distance, sometimes resulting in a sway clearance of up to 10 metres.
Before 2015, the “Clear to the Sky” requirement was based solely on the applicable distance. However, it was changed to include sway clearance, despite the fact that conductors do not sway above horizontal. Therefore, removing vegetation directly above the lines does not reduce the risk of contact.

This diagram illustrates the impact of this change.
Impact of Sway Clearance on Tree Trimming Requirements
The photos below show a tree that does not require trimming under the Minimum Clearance Space (MCS), but would need significant cutting under the current sway clearance rule. This work, which requires either a climber or an Elevated Work Platform (EWP), removes all the branches on one side of the tree, as shown in the middle photo to demonstrate scale.



Common Questions About "Clear to the Sky" Regulations
Is working in or around trees a safety risk?
Yes, working off the ground increases the risk of injury, especially in tree climbing.Will removing fewer branches improve worker safety?
Yes, reducing the number of cuts makes the job safer.Is the tree more or less likely to drop a branch in adverse weather before or after trimming?
Slightly less likely before trimming. Recent research shows that trees with full canopies are more resistant to wind stress, and removing branches can increase the load on remaining ones (see Dr James’ study).Does removing branches reduce the risk of a tree starting a fire?
No. Research by Dr Blackmore (Energex, Queensland) and Dr Coder (USA) shows that strong winds can cause branches to travel over 10 metres well in excess of the sway requirements. In the Black Saturday fires, no fires were attributed to clearance issues.Will fewer branches increase maintenance costs?
No, trimming fewer branches will not drive up costs and should reduce costs over the longer term.Is this good for the environment?
Yes, as more canopy is preserved, reducing the risk of disease entering through cuts and promoting healthier tree growth.