Protecting your Energizer from Lightning
First off, nothing is lightning proof. It is a powerful force of nature that can and will go where it wants. You may have a 20 joule energizer and think that's big. It is! Lightning bolts on the other hand have been recorded at well over 5,000 joules, which is definitely something to think about. However, lightning is looking for a path to ground and there are steps that we can take to try to help it get to ground before it gets to your energizer. Electricity wants to take the coarse of least resistance.
Lightning can get into the energizer either from your fence line wire or from your power supply side. A simple solution from the power supply side is to install a surge protector in the outlet that you have your energizer plugged into. It is best that this outlet is separated in the breaker box on a dedicated service line rather than in a series of outlets and switches.
Lightning protection should be installed at least 65 feet away from your energizers grounding system.
Fence line protection is something that you can do something about. Some farms and ranches are more prone to lightning then others. We're told that it has something to do with minerals in the soil. Anyway, there are many gadgets out there that are supposed to protect you from lightning. Some work and some don't. What you are trying to do is get the lightning into the ground before it gets to the energizer. Most protection involves a set of contacts, spark gap or such that come into play when lighting occurs. The intent is to redirect and slow the electricity down. Then, as the electricity flows through from the wire leading from the diverter to the ground field, the lightning is channeled into the ground.
Porcelain arrestors will work but usually need to be replaced when they are hit, otherwise you will have a direct short until disabled or replaced. Our MWLA unit normally makes it thru a hit unless very severe.
To be as effective as possible, the ground field for your lightning protection should be greater than that for your energizer. Based on the fact that electricity takes the coarse of least resistance, you want your lightning protection ground field to be more inviting than the energizer ground field. Therefore, if you were to have 6 ground rods at the energizer, you should have 1 additional rod for a total of 7 at the lightning field. It's a lot of work putting in that many rods, so we tend to skimp in this area, usually causing protection failure. None the less, it is our recommendation to have more rods in the lightning field than at the energizer.
If you are in a very lightning prone area you may consider installing a series of lightning protection units around your system. No lightning protection can provide 100% guarantee.