Usually not - the wire has to be able to move under the crown for the fence to work as a tensioned system.

A wire fence expands and contracts with temperature and takes impact loads from stock and wind.

If every staple pinches the wire, tension cannot equalise along the run.

The wire then breaks at a staple or pulls staples out of the posts.

Driving to leave a small clearance under the crown lets the wire slide and the fence absorb movement.

Corner and end assemblies, where the wire is deliberately terminated, are the exception.

So the two legs enter different grain lines instead of splitting the post along one.

Driven square, both legs follow the same grain and lever it apart.

A split post loses its grip on the staple and eventually on the fence.

A slight angle puts each leg into separate fibres, which holds far better.

It is standard practice and costs nothing.

Dry, dense and older posts split most readily and benefit most from the technique.

On a fence expected to last, yes - plain staples work loose and barbed ones do not.

Barbs and ring shanks resist withdrawal the way a ring shank nail does.

A wire fence is worked constantly by wind, stock and thermal movement, which walks plain staples out over years.

Re-stapling a run is far more expensive in labour than the staples ever were.

They are harder to remove, which matters if the fence will be altered.

On temporary fencing, plain staples are adequate and easier to recover.

Hot-dip galvanised as a minimum; stainless in coastal or high-value installations.

They are outdoors permanently and usually in contact with treated timber.

A staple that corrodes away leaves the fence standing on nothing, and the failure is gradual and unnoticed.

Treated posts are the common case, and the preservative in them can strip zinc from a staple within a few seasons.

Electro-galvanised staples are not an external finish despite the name.

The staple should outlast the timber, or the fence needs work before the posts do.

Yes - dissimilar metals in contact corrode at every fixing along the run.

A plain steel staple against an aluminium or differently-coated wire sets up a galvanic couple.

In a fence that is repeated hundreds of times, so the effect is cumulative rather than local.

Matching the staple's coating to the wire's is the straightforward answer.

Rainwater running down a post keeps the couple wet, which accelerates it.

High-tensile and coated wires often have a recommended staple specification from the wire manufacturer.

Long enough to penetrate the post properly, with a crown wide enough to clear the wire and let it move.

Leg length is chosen for the post material and for the load, as with nails.

Soft posts need longer legs to develop the same hold.

Crown width must accommodate the wire diameter plus the clearance being left.

Barbed wire and netting need different crown widths from plain line wire.

Heavier gauges resist bending during driving, which matters in hardwood posts.

Pneumatic fencing staplers exist and are widely used on large installations.

They drive consistently and much faster than a hammer over a long run.

Depth control is the important setting, since the clearance under the crown must be maintained.

Tool-specific collated staples are required, so compatibility is checked against the tool.

Hand driving remains normal for repairs and small runs.

In either case the angled driving practice and the clearance rule still apply.