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Note: This information is intended as general advice only and may not account for your unique circumstances such as usage habits, home and power provider. Please talk to your lines company for specific information.

Unexpected power cuts always seem to happen at the worst possible time. Whether you’re cooking, heating the home, watching TV or working, a power outage puts the daily routine out the window. But why do these impromptu outages happen?

In this guide you’ll learn things like:

  • The common reasons the power has gone out.
  • How to tell if it’s a problem with your whole street or just your home.
  • When it might be time to get an electrician around to check the wiring.

Lights out, and everyone’s home

The first thing you’ll notice when a power cut hits out of the blue are the lights going off, the TV going black and the ‘hum’ of the always-on appliances going quiet. Some household equipment may start beeping as part of their built-in alarm that power has disappeared. It might pay to check at this point if everyone at home is okay, and whether they’d been using any high-power-demand equipment leading up to the outage. While modern appliances must pass certain safety standards, any large equipment or old appliances may cause surges and fry the equipment - so check the safety of everyone and if there has been an issue like this, check for damage or fire near the surrounding area. If you’re at all concerned, give your emergency services a call (fire or ambulance) on a mobile phone with battery.

Have you checked for scheduled maintenance?

It’s not uncommon for unexpected power cuts to actually be part of scheduled maintenance. While we can’t speak for all the lines companies across New Zealand, we’ve certainly come across instances where emails and letterbox drops have been missed, or the date forgotten. If you have the means to get online from a mobile device with data, you can call the lines company and clarify what the outage is from. They’ll advise if it’s scheduled maintenance in which case it’ll be easier for them to provide you with a timeframe.

Stormy weather

Really rough weather is a regular contributor towards power cuts, especially high winds and heavy rain. Windy weather can play havoc with power lines, dislodging transformers and cables. When it comes to power lines and stormy weather, trees can be a real problem too. When lines are within proximity of damaged trees, swinging or broken branches can come into contact with the lines and poles damaging the lines, which becomes a fire risk.

For this reason, part of lines company and council preventative maintenance is a matter of cutting trees back and away from power lines. ENA’s Cut Safely website provides links to specific region’s lines company tree maintenance processes, so check out their website if you’re concerned about a tree in your community that presents a risk during a storm.

In other situations, flooding can cause power outages with water damage to underground lines or local infrastructure. Flooding, while less common an issue, makes maintenance hard and sometimes impossible in severe cases.

Damage to lines

Damage to a powerline can be caused by more than just the weather. In the situation of a serious car or truck crash into a powerline, the electricity for an entire street or suburb can be affected. As emergency services and then maintenance is conducted, the outage can last some time. Damage can also be caused by animals climbing, chewing and breaking components on a power pole - not a great idea for the animal but this can happen. The design of modern power poles are intentionally robust, built to withstand a considerable level of destruction, but there are occasions when damage can cause an issue.

There are also issues like flying a drone into the lines, or unintentional damage done during routine maintenance. While such instances are rare, they do happen.


Power station fault

Faults are part of any electrical equipment - and the power station is no exception. The number of components and complexity of a power station means that when something fails or shorts, it can take a while to first diagnose and then fix the issue. Luckily, it’s part of all power lines companies’ process to conduct regular maintenance and diagnostics on their infrastructure to get ahead of such issues as much as possible.


There’s also back up plans when things go wrong, so if there’s a power cut from a fault, it’s likely to be something a bit more complicated.

Circuit breaker or switch issue in your mains box

With homes in New Zealand spanning many decades, it’s not unusual for the mains to have an issue that triggers a power cut. The mains box will be around the side of your property and is made up of a number of switches/circuit breakers that prevent excess power from entering your home - each of the switches control different areas of the home’s power, and ideally will be labelled accordingly (e.g. “lights” or “kitchen”). There will also be a mains switch which controls the entire home’s access to power (on or off). This mains switch can be ‘tripped’ when a sudden surge of power or fault occurs in the home. Once you’ve checked there is no risk or danger within the home (e.g. a fried appliance), you can switch the mains back on.

However, any visible signs in the fuse box of damage, burns or loose componentry means one thing: call a professional electrician. It’s simply not worth risking your personal safety.

Wiring problem in the home

Older homes in particular can experience wiring issues, from loose fittings, exposed wires, wear and even the odd nibble from rodents or insects. Old wiring materials aren’t as hard wearing as modern electrical wiring materials so they’re commonly more susceptible to problems. The most important thing to get checked however is whether the wiring is safe for the household and fully functional. You won’t immediately need to replace slightly older wiring if everything is intact. But an electrician will be able to access and review the state of your wiring for you, providing recommendations as to what parts may need replacing (or indeed if the whole home needs a re-wiring).

As a full rewire is certainly a noticeable cost, many homeowners will combine the rewiring with upgrades like installation of new lighting, ventilation, security or audio - tackling this job with a full rewire so the no-power downtime is concentrated inside a day or two at most.

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Find out how much you could save on power. Upload a bill and get a free  estimate:

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