Fence Wire Spacings
"I'm about to build a 7 wire fence and don't know what the spacing between the wires should be". It's a common question to which there is more than one correct answer.
Wire spacings vary depending on region, type of stock being grazed, personal preference, or number of wires on the fence (which also varies depending on all the preceding reasons). Historically, fences in the North Island were more substantially built than those in the South Island. Contour and soil types have a lot to do with that - many North Island soils being more erosion prone than the South. Stocking rates were also higher in the North, with more cattle than sheep being run, with a consequent increase in stock pressure on fences.
Boundary fences are covered by the Fencing Act 1978 - which has some definitions of specimen types of fence for rural situations - covering 7-8 wire, 9-10 wire, prefabricated (netting) fences and live fences. The definitions are reasonably specific as to most things, but don't give exact spacings for line wires - just maximums.
The table below sets out a few alternatives, or you can copy the spacing from an existing fence on the property. (All measurements are in mm):
|7 wire spacing to suit cattle||
7 wire spacing to suit sheep.
Also matches the hole spacings in steel Y-posts/waratahs
|8 wire spacing to suit cattle or sheep||8 wire spacing to suit sheep
Also matches the hole spacings in steel Y-posts/waratahs.
Stepping up to 9 or 10 wire usually involves adding a lower bottom wire 60 - 75mm off the ground, possibly in conjunction with an increase in fence height, closing up the gaps 2nd and 3rd from top to accommodate an extra top wire.
A wire and batten fence isn't cheap to put up, but there are effective alternatives without the battens. If you need to contain or exclude stock, and battens aren't essential - consider the following alternatives:
An 8-wire unbattened fence with 2 of the wires electrified can be as effective as a wire and batten fence and isn't vastly different in cost to a 4 wire all electric fence.
Without battens, electric wires are an absolute must if stock pressure on the fence is likely. Having the occasional lamb getting through a fence isn't always a problem - they'll usually cross back to get to their mother when they're hungry, but cattle will eventually damage an unbattened fence unless it is electrified with one or more hot wires.
Modern barbed wire was invented by Joseph Glidden in the USA in the late 1860s/early 1870s, and first appeared in New Zealand in the late 1870s. It was mainly used on cattle farms, and most fences had a barbed top wire. These days barbed wire has lost its popularity - there have always been concerns about it because of the damage it does to animal hides and pelts. Electric hot wires are sufficient discouragement for most cattle from pushing against a fence. The only other argument in favour barbed wire is to stop battens sliding along a fence, and that can be overcome with proper batten stapling techniques. Barbed wire still has some application in predator fences - particularly where feral pigs are the species you're trying to exclude. If used in a general farm fence, second wire down is preferable to top wire.