New Zealand's Electrical Current - Volts/Hertz
Electrical current is supplied domestically throughout New Zealand at 230/240volts, 50 hertz. Most accommodation providers provide a 110 volt ac sockets (rated at 20 watts) for electric razors only.
Be warned: If you try to use 110-volt appliance like an iron, hairdryer or shaver in a 230/240volt plug the high voltage could overheat and destroy the appliance - a power converter is required to use these appliances, but such a device would be the size and weight of a brick and not practical unless.
Thankfully today most low-power devices like laptop and phone chargers power supplies will work on both 110 and 220 volts. Look for a plate or printing on the device, and it will probably say "110-220 volts" (refer to the below image) and therefore the devices need only a plug adaptor. Most motels/hotels will supply a hairdryer.
How to know whether you need a converter or transformer. Check the manufacturer's label (see image below). If the tag has a single voltage number (110 or 120 volts), you do; if you see a combined low/high number (120/240 volts or 100/240 volts) or digits of 200 or higher, you don't. But not all your appliances need converters or transformers before you can use them.
But seriously folks bringing a converter or transformer is just not worth the hassle. If you just absolutely need those curling tongs then they can be bought cheaply at places like The Warehouse/K Mart.
Converters are meant for electrical appliances, and should only be used for a short period (1 to 2 hours). A 50-watt converter will do for small electrical appliances, like (non rechargeable) shavers or toothbrushes, and non-heating appliances. For heating appliances (such as hair dryers, irons, coffee makers and other high-power electrical appliances) you need a 1600-watt converter. To find out which converter you need, check the label on your electrical appliance for its wattage.
Transformers are to be used with all rechargeable appliances (for instance battery rechargers, cell phones, laptops and rechargeable shavers). Again, you’ll only need a transformer if those appliances are designed for another voltage level than the one in use in New Zealand (230V) and are not dual-voltage.
Dual-voltage: Some appliances are dual-voltage, which means they can be used with more than just one voltage level. To check if that’s the case, look for something like this 100-240 Volt ~ 50/60 Hertz on the nameplate of your appliance. And of course don’t forget to switch the voltage level manually before you plug your device into a New Zealand outlet!
NOTE: Laptops and battery rechargers usually come with switch-mode adapters (which means they can switch an AC input (100-240V for example — check the label!) to a DC output (19V for example). They can be plugged right away into a New Zealand outlet with the right power plug.
And what about the frequency: can I use a 60 Hz appliance into a 50 Hz outlet? No, we wouldn’t recommend doing that. Even if the voltage is the same (or if you use a converter/transformer to adjust the voltage), a 60 HZ appliance may not function properly on 50 Hz current. Fortunately, some appliances can operate on either a 50 Hz or 60 Hz system. This has to be stated on the name plate, like: 110-230 Volt ~ 50/60 Hertz.
Tip: Bring a rechargeable power bank or power pack that extends a device's unplugged life (like a phone or camera) by many hours. These can usually be charged from anything that has a USB outlet.
This manufacturer's label indicates that the device can only run on 120 volts so could not be used in New Zealand...