From www.airnz.co.nz
PC Power Operation

PC Ports are available in Business class on A320 aircraft, and in Business Premier and Pacific Premium Economy on B777 and B747 aircraft. The in-seat outlet unit provides 11OV at 60Hz. The outlet plug accepts most common connector plugs including:

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3-pin New Zealand or Australian plugs
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2-pin European plugs
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2-pin or 3-pin USA plugs

The outlet plug does not accept 3-pin British plugs. For use of devices with this type of plug, an adapter is required. Adapters are not available onboard Air New Zealand services.