Okay you need more than just hotcote - you need a seriously powerful zapper with an excellent grounding system. I got in an electrician to help my husband with the grounding system on my fencing - three ground rods driven 8 feet into the ground. I keep the ground around those ground rods very wet and they are enclosed in a perimeter chain-link fence to keep people and animals out - touching a ground rod that happens to get activated is a great way to get dead. Also periodically the electrician and my husband installed extra ground rods throughout the perimeter areas because we have a lot of acreage to cover.
But the whole point of this is you need some serious zapping power. It is NOT too much to consider 15,000 volts for a horse.
The zap doesn’t come from the zapper. The zap is strongly dependent upon the grounding system. The better the ground, the more reliable and better the zapping system becomes.
My horses absolutely FEAR my fence far more than anything another horse or object can do to them. They will always turn in a different direction than my fence. At the farthest point in our 60 acres, our fence registers a 12,000 volt power zap. Closest to the grounding system and zapper, it registers 15,000volts on the tester.
There is nothing safer for your horse than a fence your horse fears more than any other possible monster.
Also, NEVER turn off your electric fence. Periodically turning off an electric fence to “save money”, teaches a horse to test the fence. This is just asking for very expensive vet bills when the horse spooks or tries to get away from another horse and they have learned that sometimes the fence isn’t on so they become willing to risk trying to run through it or attempt to go over it.
If you have electric fencing, just accept the cost of running it 24/7/365. Period.
My gelding (now deceased) was a Werther grandson. The boy was a powerhouse and could jump. We watched him clear a 6-1/2 foot fence taking 1 stride from a stand still, just 'cuz he felt like it - when you have a horse like that, this is a problem! But, put him inside a 4 foot fence topped with electricity and he would never consider it. Ever. You couldn’t get him within 5 feet of the fence. In his mind, that zap could get him no matter where he was. He became very alarmed if he ever heard it zap and would back away snorting.
Hotcote is white, correct? It has very high visibility, but I would add a solid white top rail with very high breaking strength and top that with yet another electrified strand. Better yet, is no-climb mesh fencing with a top rail, topped again with electricity. But if you go with hotcote fencing, plan for 4 strands - top strand hot, 2nd strand ground, 3rd and 4th strands hot. The ground strand allows a double zapability system - no matter what line they touch, they will get zapped. Should they somehow be airborne and touch the fence, the ground strand will still activate and they will be zapped. Obviously with their hooves on the dirt, touching any strand will activate the zap.
On a perimeter fence with a powerful zap, you should post warning signs every X feet. Otherwise, some kindly elderly person could reach across the fence to pet the pretty noses and the zap would stop their pacemaker. Seriously. It would destroy a pacemaker and that might cause their death.
Check your zapper to make sure it has ultra-impedence. This means, no matter if shrubs, tall grass, whatever, are touching the fence, the current will still flow. Also choose a zapper that has enough juice to do double the miles you have for your fenceline. When you’re adding more than 2 strands, the mileage adds up pretty impressively.
PS: You also need to install a system to protect your zapper should lightning strike your fence. Lightning very keenly follows an electric fenceline right back to your zapper. The last thing you need is an explosion inside your barn or wherever you happen to have the zapper. Ever seen a transformer blow up when struck? Zappers can do similar, albeit is a smaller version of said explosion, but enough to cause considerable excitement!
