How Do I Safely Dig Near an Overhead Power Line on My Property?

Digging near overhead power lines is one of the most hazardous tasks a homeowner or contractor can undertake. In New Zealand, strict rules govern how close you can work to live lines — and getting it wrong can be fatal. Before you pick up a shovel or call in an excavator, here's what you need to know.

Understand the Risks First

Overhead power lines are almost always live and uninsulated. Contact between an excavator boom, a raised truck tray, or even a long-handled tool and a power line can cause electrocution, arc flash, or fire. The danger zone extends further than most people realise — electricity can arc through the air before physical contact is made.

WorkSafe NZ treats electrical incidents near power lines as a leading cause of serious harm on worksites, and the same risks apply to residential properties.

Know the Safe Approach Distances

In New Zealand, safe approach distances (also called exclusion zones) are set out in the Electricity (Safety) Regulations and relevant standards. As a general guide:

Important: These are minimum distances for trained workers with appropriate controls in place. For untrained homeowners, the practical advice is simple — do not work within these zones at all without first contacting your local lines company.

If you are unsure what voltage the lines on or near your property carry, assume the worst and contact your network operator (e.g. Vector, Powerco, Orion, WEL Networks, or your regional lines company).

Step-by-Step: Before You Dig

1. Identify All Lines and Services

Before any excavation, identify both overhead and underground services. Overhead lines are visible, but underground cables may run from the street pole to your house beneath the ground. Use Dial Before You Dig (0800 248 344) or contact your local council and lines company to get service plans for your property. or contact your local council and lines company to get service plans for your property.

2. Contact Your Lines Company

Phone your local electricity network operator well in advance — ideally at least five working days before work begins. They can:

• Confirm the voltage of the lines
• Advise on exclusion zones specific to your situation
• Arrange a temporary disconnection or line cover (insulated line guards) if required
• Send a lines worker to supervise high-risk work

Note that temporary disconnections or line guarding may incur a fee and take time to arrange, so plan ahead.

3. Assess Whether a Building Consent Is Needed

If your excavation is part of a larger building project, check with your local council whether a building consent is required. Some earthworks are exempt under Schedule 1 of the Building Act, but this depends on the scale and nature of the work. Always confirm with your council — do not assume an exemption applies. See MBIE Building Performance for general guidance.

4. Brief Everyone on Site

If you're hiring an excavator operator or other contractors, make sure everyone on site is briefed on the location of overhead lines and the agreed exclusion zones before work starts. A spotter — a dedicated person watching for line proximity — should be used whenever machinery operates near lines.

Safe Working Practices During Excavation

• Never assume a line is dead. Treat every overhead line as live at all times.
• Keep all plant, equipment, and materials (including spoil piles) outside the exclusion zone.
• If using an excavator or crane, the boom, bucket, and any load must all stay within safe distances — not just the machine body.
• Avoid working in wet or windy conditions near lines, as these increase risk.
• If a line is accidentally struck or brought down, do not approach it. Call 111 immediately and keep bystanders well clear. Stay in your vehicle if you are inside it — do not jump out.
• Wear appropriate PPE, though note that standard PPE does not protect against electrical arc flash at these voltages.

Restricted and Licensed Work

Any work that involves physically moving, connecting to, or altering an overhead power line is restricted electrical work under the Electricity (Safety) Regulations. This must only be carried out by a registered electrician or lines company worker. Homeowners cannot legally perform this work themselves.

For guidance on what is and isn't restricted electrical work, visit the Electrical Workers Registration Board (EWRB).

Safety note: If you are ever in doubt about whether it is safe to proceed, stop work immediately and seek professional advice. No project timeline is worth a life.

When to Call a Professional

You should engage a qualified professional in the following situations:

• The excavation will bring any machinery or equipment within the safe approach distances listed above
• You need lines temporarily de-energised or covered — your lines company must arrange this
• The project involves significant earthworks close to the property boundary where lines enter the site
• You are hiring an excavator and the operator is unfamiliar with the site hazards

A qualified excavator operator experienced in working near services is your best asset. You can find licensed local excavation contractors on tradedirectory.co.nz who understand NZ regulations and safe working practices.

Sources & Further Reading

• WorkSafe NZ – Working Safely Near Power Lines
• MBIE Building Performance – Building Consents and Exemptions
• Electrical Workers Registration Board – Restricted Electrical Work
• BRANZ – Site Safety and Services
• Standards NZ – Electrical Safety Standards