Plan the line and the power first
Walk the boundary before you buy anything and decide where the fence will run, where gates and corners fall, and where the charger will live — under cover, near its earth, and reachable in the dark. Size the charger to the total length of fence you will eventually run, not just today's paddock, because an underpowered charger gives a weak pulse that bold horses learn to ignore. Mains chargers suit permanent yards; battery and solar units work for strip grazing and remote fields but need their batteries checked and charged on a routine, not when the fence dies.
Posts, tape and strand heights horses respect
Horses respect what they can see. Use wide tape or thick rope rather than thin wire — a horse galloping towards a fence line reads a broad white tape far earlier — and keep posts firm and evenly spaced so the line stays taut and level. Two or three strands suit most horses: the top strand at about chest height on the average horse, with the lower strands stepped down beneath it, lower again for ponies and foals. Corners and gate ends take the strain, so brace them properly, use insulators made for the job on wooden posts, and never tie tape directly to a post or a tree, where it shorts and frays.
The earth is half the fence
More electric fences fail at the earth than anywhere else. The charger needs its own earth rod — ideally more than one on long fences — driven deep into soil that stays damp, well away from water pipes and building earths, and connected with proper cable. Keep vegetation off the lines: grass and weeds touching a strand bleed the pulse away, which is why fences weaken as summer growth comes on. Once the fence is up, walk it with a fence tester and check the reading at the far end, not just beside the charger, then re-test after you strim, after storms, and whenever a horse starts leaning on the line.
Teach the horses, then maintain the line
Most horses need one investigation of a working fence and then give it respect for life, so make sure the fence is fully live before turnout rather than letting a horse learn on a dead line that it can push through. Introduce a new horse to an electric-fenced field in daylight, watch the first hour, and never put a panicked or newly arrived horse straight out behind tape alone. Afterwards, maintenance is small but constant: tighten sags, replace frayed tape before it breaks, clear regrowth, and check the charger is pulsing every time you pass it.
A good fence keeps horses in almost all of the time — but almost is not always, and a loose horse on a road gives a stranger minutes to help, so back the fence up with KinsLe's Verified QR ID Pet Profiles: a unique QR tag on the halter lets whoever catches him scan straight to his profile and reach you, instead of your number depending on whether anyone at the yard gate knows it.