Plan your system
Fence-line connections, the power line, and the ground line don't work the same way for a new fence as they do for adding electric strands onto a fence you already have.
Wiring a new fence
Not as a default — an existing metal fence usually isn't a controlled, consistent earth path. Install a proper earth rod system near the energizer, and keep the existing fence out of the electrified circuit unless staff have reviewed your specific site.
Roughly 15cm out from the fence face is the usual starting point — see the Strand Height Planner's "Existing fence" mode for height-by-height detail.
Roughly 1 rod per 1.5 joules of stored energy, minimum 3, with more added in dry or sandy soil where conductivity is poor.