Number 8 wire is a 0.16"-diameter gauge of wire on the British Standard Wire Gauge that has entered into the cultural lexicon of New Zealand.
Number 8 wire was the preferred wire gauge for sheep fencing, so remote farms often had rolls of it on hand, and the wire would often be used inventively to solve mechanical or structural problems. Accordingly, the term "number 8 wire" came to represent the ingenuity and resourcefulness of New Zealanders, and the phrase "a number 8 wire mentality" evolved to denote an ability to create or repair machinery using whatever scrap materials are available to hand.
Since 1976 when New Zealand adopted the metric system, number 8 wire is officially referred to as 4.0 mm gauge wire, although the older term 'Number 8 wire' continues to be commonly applied. Fencing now predominantly uses 2.5 mm high-tensile wire.
The Waikato Museum runs an art award named after the wire.cf.