Connecting a portable generator to your home can keep the lights on during a power cut, but it must be done correctly — both for your safety and to comply with New Zealand electrical law. The short answer is: you can run appliances directly from a generator using extension leads, but any permanent or semi-permanent connection to your home's wiring must be carried out by a licensed electrician.
Why This Is Serious — Backfeed and Electrocution Risk
The biggest danger when connecting a generator to household wiring is backfeed — where electricity generated by your unit travels back along the lines to the street, potentially electrocuting line workers who believe the network is de-energised. This is not a theoretical risk; it has caused deaths. Even a brief, accidental backfeed can be fatal to someone working on the network nearby.
For this reason, WorkSafe NZ and MBIE Building Performance take generator wiring very seriously, and New Zealand's electrical regulations are clear on what is and isn't permitted.
What the Law Says: Restricted Electrical Work
Under the Electricity Act 1992 and associated regulations, any connection of a generator to fixed household wiring is restricted electrical work. This means it must be designed, carried out, and certified by a registered electrician — someone registered with the Electrical Workers Registration Board (EWRB).
Doing this work yourself, or hiring an unregistered person, is illegal and could void your home insurance. Always ask to see your electrician's current practising licence.
The Safe, Legal Options
Option 1: Direct Plug-In with Extension Leads (DIY — Safe and Legal)
The simplest and safest approach is to run appliances directly from the generator using heavy-duty, outdoor-rated extension leads. This requires no connection to your home's wiring at all.
- Plug appliances (fridges, lamps, phone chargers) directly into the generator's outlets
- Use leads rated for the load — check the amperage and wattage ratings on both the lead and the appliance
- Keep the generator outdoors at all times — never run it in a garage, shed, or enclosed space due to carbon monoxide risk
- Position it at least one metre from windows, doors, and vents
- Use a residual current device (RCD) on the lead for added protection
Option 2: Transfer Switch (Requires a Licensed Electrician)
A manual or automatic transfer switch is the correct, legal way to connect a generator to your home's switchboard. The transfer switch physically disconnects your home from the network before connecting the generator, eliminating backfeed risk entirely.
- A manual transfer switch requires you to flip a switch before starting the generator
- An automatic transfer switch (ATS) detects a power outage and switches over automatically
- Your electrician will install the switch at your switchboard and may need to obtain a building consent or notify your lines company — check with your local council and electrician, as requirements vary
- Once installed, your electrician issues a Certificate of Compliance (CoC), which is your legal proof the work was done correctly
Option 3: Interlock Kit (Requires a Licensed Electrician)
A generator interlock is a mechanical device fitted to your switchboard that prevents the main breaker and generator breaker from being on at the same time. It's a lower-cost alternative to a full transfer switch but still requires installation by a registered electrician.
Sizing Your Generator Correctly
Before buying or hiring a generator, work out what you need to power. A rough guide:
| Appliance | Approximate Running Watts |
|---|---|
| Fridge/freezer | 150–400 W |
| LED lighting (per circuit) | 50–200 W |
| Chest freezer | 100–300 W |
| Sump pump | 750–1,500 W |
| Electric kettle | 2,000–3,000 W |
Note that many appliances (especially motors) have a higher starting (surge) wattage than their running wattage — your generator must handle both. A licensed electrician or generator supplier can help you size the unit correctly.
Generator Safety Essentials
- Never run a generator indoors or in an attached garage — carbon monoxide is odourless and can be fatal within minutes
- Store petrol safely in an approved container, away from the generator and your home
- Allow the generator to cool before refuelling
- Check the oil level before each use
- Test your generator before an emergency, not during one
- Keep a working carbon monoxide detector inside your home — available from hardware stores
- Earthing: your electrician will ensure the generator is correctly earthed as part of any fixed installation
Notify Your Lines Company
If you're having a transfer switch installed, your electrician will typically notify your local lines company (e.g. Vector, Orion, Unison, PowerNet). This is standard practice and ensures network operators know a generator connection exists at your property.
When to Call a Professional
Call a registered electrician for any of the following:
- Installing a transfer switch or interlock at your switchboard
- Running a dedicated circuit or outlet for a generator
- Assessing whether your switchboard is suitable for a generator connection
- Any work that involves opening your switchboard or modifying fixed wiring
You can find qualified, local electricians on tradedirectory.co.nz. Always confirm they are registered with the EWRB before work begins.
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