Wires should be 5-6 inches apart. Every second one from the bottom is a ground wire. This will deliver the full voltage across any two adjacent wires, thus avoiding any grounding losses, especially if the ground is dry. It is also important to use a fencer with at least 7000 volts output. The more the better.
Larger hunting dogs fenced into the vineyard can be highly effective. Just make sure they are well cared for and given attention.
Netting for raccoons, generally will not work. They will just rip it apart.
Another bit of last ditch advice taken from the internet:
Mix up some fly killer and coke. They won't make it 6 feet after drinking it.
Netting must be installed well away from the grapes themselves and all openings closed.
Bird scaring devices and reflective tapes are ineffective. The birds become adjusted to them in a few days.
Keep vegetation removed and/or low to expose rats to predators. Place rat poison at the base of the vines that look 'most attractive to the rats'. Continue till grapes are picked.
When wasps come snooping, I spray a light mist of insecticide on the ground beneath the grapes (none on the grapes). My grape clusters are one to three feet above the ground. This gives off enough of a smell to deter the wasps. Is it because they don't like the smell or because it masks the smell of the ripening grapes? I don't know. But it works - til it rains - then repeat. Your mileage may vary.
I plan on rigging up some kind of vaporizer for the insecticide or some other obnoxious smelling stuff (think creosote or ????). This vaporizer would contain whatever I used, so that their would be zero contamination to the soil. Nor would the fruit be affected in any way. It would last longer and be stronger. Until proven, this is just another hair brained idea of mine.
Aside from whites, Foch is the very worst grape for attracting wasps. Even though they ripen later than the Marquette, the wasps will attack the Foch before the Marquette. I have one Foch that I sacrifice to the wasps on a bad year. I place a traps all around it. This helps keep the pressure of the other plants.