Satellite TV TVRO Lightning Protection
A discussion on how to protect your Satellite TVRO installation from Lightning.
Lightning and thunder! Now your LNB is dead. But you just replaced it. Why did it die again? Did Dave sell you a bad LNB or did you sacrifice it to mother nature ? We will show you why you are having these problems.
Two things you need to know, and remember. First electricity always follows the least path of resistance. Second the National Electrical Code requires that certain grounding be done. Both of these issues are your problem.
Take a look at the next diagram. It shows the typical home satellite installation.
Yup, that what I have alright, but whats wrong with this, I have it grounded just like I am supposed to. Do You? Well, maybe... depending on interpretation of the code, but not for your equipment sake.
Take a close look. The only thing connecting that dish way out there in your yard to your receiver is the coax, the actuator wires and the servo wires. Now lets suppose that lightning hits one of those new fangled cellular towers 20 miles away. Surge current will flow for miles around due to that strike. We all know that the surge is flowing in the earth, but we also know that the current will take the path of least resistance. Well, when this surge gets to your yard, guess what, the earth is not the least resistance anymore, your wires between the dish and your house/receiver are now the best path. So what? Well, while it is taking the least path through all your expensive equipement it is also doing damage to it. Think of your LNB as a fuse, poof ! If you are lucky that is all that will go poof. You see you have made mother nature a nice path for current flow by driving that ground rod out at the dish, and the electric and telephone companies have made the other end at the house by setting their ground rod(s) there. So the current flows through the earth, arrives at one of end of your yard, enters your system via the electrical wires or grounds or both, and travels through your gear, then back out to the earth via the other end to carry on it travels.
So, ok now what do I do then?
Take a look at this next picture. There is still a ground rod at the dish, code inspectors are a happy lot of people...Yea ! But, now you have moved your satellite wires from the old place where they exited the house to a spot close (very close) to the utility meter ground area. This is the place incidentally where you want to place most of your surge blocks, protectors and other ground stuff. We call it the demarcation and central ground point. Then you run a connecting ground wire from the ground rod at the dish to the ground rod at the utility meter area. What you are trying to accomplish is to offer the surge the best path through your newly added ground wire instead of via your coax,servo control wires etc.
In fact I much prefer my LNBs and feed assemblies to be electrically isolated from the dish metal and have them mounted on insulators on my dishes that are out in the yard. I do not at that stage ground the LNB or Feed, only the dish support pipe. Does that meet code, I don't know and don't really care, it saves my gear.
Ok, that is just great, but I can't move my wires to the area of the utility grounds or I just plain ole don't want to.
Thats too bad really, it will save you money. But there is a work around that you can do. Take a look at the next picture...
What you see here is that the wires still exit the house at the same ole spot. But, where they exit, you have added a ground rod and put your surge protectors and ground blocks there as well. You did get grounding stuff didn't you ? Next you added a ground wire from the dish ground rod to this new ground rod. Very good ! But, you are not finished yet, you still have a path through your gear. Fix it quick with another ground wire from the new rod to the utility meter ground. This way you are still offering mother nature a lower resistance path around your gear.
Will all ground stuff positively stop lightning damage. No, but it will help. I have tried to present this information in a simple fashion. I know that many arguments can be presented for proper ground methods. I have done grounding work for many years and can tell you we can get knee deep in theory texts to our hearts desire. As usual this information is presented in a nothing is guaranteed basis and you are instructed to consult with proper authorities concerning the National Electrical Codes for your equipment.
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