Trees and powerlines are one of the most regulated areas of arboriculture in New Zealand. The rules exist because contact between a tree (or even a tool) and a live powerline can kill, and because trees on lines are a leading cause of network outages and bushfires.
The Electricity (Hazards from Trees) Regulations 2003
This is the core regulation. It defines "growth limit zones" around overhead electricity lines: a notice zone (further out) and a closer growth limit zone where vegetation simply isn't allowed.
For most overhead distribution lines (the lines feeding your street), the growth limit zone is about 1.5–2.0 metres from the line. The notice zone extends further, typically 3–4 metres. Specifics vary with voltage.
Who is responsible
If a tree on your property is growing into a powerline:
- First cut to clear: usually paid by the lines company (Vector, Wellington Electricity, Powerco, Aurora etc. depending on region). They'll send a contractor to clear the tree back to a safe distance, often more aggressively than you'd prefer.
- Subsequent cuts to keep clear: usually the tree owner's responsibility (you).
- If the tree is between the line and the road and the lines company has maintenance access: they'll keep doing it. If not, they'll require you to.
Close-approach work
Any tree work within 4 metres of a live line, even if the line is fully insulated, requires a Close Approach Consent from the network operator. The work must be done by an approved close-approach contractor following an approved plan.
"I'll just trim the top with my saw" is how people die. The rules exist for very good reason.
What to do about a tree you're worried about near a line
- Call your lines company. Most have free vegetation-around-lines hotlines and will assess your tree at no cost.
- Get an arborist to assess. If the tree is otherwise healthy, options include reduction pruning (under the lines company's notice) or removal.
- If it's an emergency: tree visibly lifting into a line, line down across the tree, call your lines company first. They de-energise the line before any tree work happens.
If a tree has brought a line down
- Don't touch the tree. Don't go near the tree. Lines can re-energise without warning.
- Stay at least 10m away.
- Keep others (especially children, pets) away.
- Call the lines company emergency number (on your power bill).
- Don't move vehicles parked under the line.
- Call us second, we'll dispatch as soon as the lines company has the section de-energised.
Planting near lines
Don't plant trees that will grow into lines. Lines companies publish planting guides for their regions, generally:
- Within 4m of the line: only shrubs growing under 3m mature height.
- Within 8m of the line: trees growing under 6m.
- Beyond 8m: any height.
"Within 4m" includes horizontal distance, measure from the line, not the pole.