This is a rant, so bear with me.
First, let me start by saying I should have KNOWN better. I am a broadcast engineer and deal with high RF environments, complicated studio setups, ground loops, and ESPECIALLY grounding/shielding techniques. It is this last thing that I am getting sick of.
Bought my house in 03. Here is backwater TN, they are not as "technically" inclined as one would hope. My home didn't come with any networking, or cable runs other than the typical single cheap RG6 run and phone jack in all the rooms.
I spent a great deal of time and effort wiring up my home with multiple ethernet jacks in every room (except bathrooms and kitchen, LOL).
The root of the problem is everytime we have a storm, something in my house gets blown up. To date I have lost:
2 satellite receivers
3 PCs (network cards blown to hell)
2 network switches (same switch popped twice)
and a Xbox twice.
Fortunately, my living room "HT" setup has not suffered any damage (knock on wood) as there are some pretty long runs in wall between the equipment rack and TV, but nowhere near as long as my CAT5e runs.
Yes, i have surge supressors in all rooms with all gear. Nothing fancy, just the "monster" brand MOV variety. However, in my experience, surge suppressors don't ELIMINATE the possibilities of lighting damage, they just REDUCE the likelyhood of damage with strikes.
Where I work we have a 300 ft lighting rod (radio tower) out back, and although we do suffer damage occasionally, its nowhere near the extent I do a home.
Now, the satellite receivers/multiswitch I don't *think* I can do anything about; think those were a fluke. In my mind the root of the problem is my PC network.
In every case above, i am conviced the long cable runs "picked up" the energy from a nearby strike, creating a massive current flow in the cables themselves, wiping out equipment at the ends of the cables. I do not believe power line induced surges are a problem at my house.
Lightning is a funny thing, but understanding what causes damage from storms isn't as complicated as one would seem. Its pretty easy to understand actually. Dealing with it, is also not too complicated as well.
Basically, anyone with a BEE background understands that if you have a conductor, and you run current through that conductor, it will generate a magetic field at right angles to the current flow. Conversely, if you take a magenetic field and run it through a conductor, it will generate a current flow. This is the basics of how a motor or generator works.
Now, a lightning strike introduces a MASSIVE amount of current. Also, at the same time a MASSIVE magenetic field is created. As that magnetic field travels it will induce current flow in any nearby conductors (as in, my network cat5). Such massive current flow induced into the conductors will cause the associated voltage drop on the devices at the ends of the conductors, and usually that voltage drop is substantially higher than the operating voltage of the equipment, and as a result, the "magic smoke" gets let out.
A real good example of this phenomenon happend to us years ago. We took a *direct* massive lightning stike on our tower out back. Although we suffered no damage at the time, every CRT monitor in all 3 buildings in our premises turned all sorts of different colors; as if a magnet had been run accross the screen. (Fortuneatly, we had a "bulk eraser" designed for erasing magetic tape that fixed them all-in effect acting as a"degausing coil").
Now, there is some good news. The energy generated by a lightning strike behaves logrythmicly, not linearly. What that means is, if you double your distance from the strike, the amount of energy that would be "picked up" would go down 10 fold. Very similar to the way that amplifier power and perceived loudness works (if you have a real 100watt amplifier and want to "double" the loudness to a given speaker, you need to increase the power to 1000watts).
So, the further you are away from the strike, the better off you are. And since the energy decreases rapidly with distance, you don't have to be too terribly far from it to be okay.
The problem is, where I live, I have crap all around me that lightning loves to hit. Neighbors put up flag poles (while a patriotic gesture, this has caused me more grief than anything else, as I have witnessed direct strikes to them, and the associated damage along with it), and rather large trees in the far back of my property.
This is the first house I have had this problem with (and coincidently, my very first home purchase....grrrrr).
So, basically, you either live in an area prone to nearby damaging strikes, or you don't. I fall in the former category.
So, what can be done to minimize the potential for damage you might wonder...Three things:
1) Surge suppression
3) Proper grounding
Lighting can easily be induced into power lines, phone lines, cable, or any other conductors coming into the home. The longer the conductor, the "better" of an antenna it is for picking up energy from lightning.
So, the first place to start is surge suppression. I won't go into it, just suffice it to say that I am not one to spend large amounts of cash, so I have inexpensive suppression. But obviously, different types of suppression are better than others, and *generally* you get what you pay for. However, in my opinion, NO suppressor can ELMINIATE the potential for lightning damage, only reduce the likelyhood for it.
They sell whole house suppressors (very good invenstment IMHO if you can afford it)-its what we use at work.
Then you have the plug strips with suppression (I have this type). They also sell coax cable surge suppressors, which I have in my HT setup only. I do not know if S-video protectors are available, or if coax type suppressors are suitable for component video use or not.
Although they *do* make and sell surge suppressors for ethernet networks, they are *TERRIBLY* expensive.
The problem is that although you may have perfect surge suppression on your ac line and phone, if you have really long cable runs, ac line protection only isn't going to help.
So, that brings us to the 2nd line of defense-Shielding; Something that is not really considered too much in the home environment, and this is exactly where I went wrong. If you could "shield" the signal carrying conductors inside a cable, and "drain" off any induced energy to ground than that would really help protect the equipment located at the ends of the cables. Fortunately, they DO SELL shielded cat 5/e cable.
Which brings us to the last, yet IMHO MOST important thing you can do to help reduce the likelyhood of damage, and that is proper grounding.
I say it is the most important, because more often than not, Suppression relies on a LOW impedance earth ground to be effective. Shielding ALWAYS relies on a low impedance earth ground to be effective.
So, what is the big deal about grounding you might wonder. Well, even the *best* conductors have resistance. If you flow enough current thru a conductor, you WILL drop voltage. The larger the resistance, the more voltage you will develop for a given amount of current. Again, with the massive amounts of current developed by lightning, you want the aboslutely lowest impedance to earth ground you can get.
Not sure about where you live, but where I live, that is a problem. Although most homes where I live the ground rod is not visible, most of the time I have seen them use galvanized ground rods. There is nothing wrong with that in itself, except the conductors used to attach to the rod are usually copper. Galvanized doesn't "talk" to copper very well, and you end up with "dissimilar metal corrosion" over time. So your "ground" although will still protect you from electrical shock from a major appliance malfunction, it doesn't help much in the way of nearby lightning strikes because as the corrosion builds up, the more "resistance" to earth ground it has, and the more voltage is allowed to develop on the "ground" conductor during storms.
So, start with a good ground, along with shielded cable, and quality surge suppression, and you should have a nearly bulletproof (notice I said "nearly!) setup.
In my case, I have driven a copper clad steel ground rod next to the main service ground, and tied the two together (very important-if you don't, you will have dissimilar imedances from the two grounds which will manifest itself as ground loop issues, and actually increase the likelyhood of damage from lightning due to the difference in potential of the two separate grounds). I have also brought in 2" wide ground strap that we use in our industry (heavy guage wire should do nicely; the bigger, the better), and attached it to my ethernet rack, grounding all equipment that is bolted to the rack.
The last thing I need to do, and was the whole purpose of this thread, is rip up ALL my cat5/e in my house and re-run it with SHIELDED cat5/e. The important thing with shielding, is you only ground the shield on ONE END only, which means my distribution point, all shieldes will get bonded to the ground strap, which should majorly reduce the amount of damage I am taking.
So, my point of this post (aside from making myself feel better) was that if you are doing new construction, and you live in an area that is prone to nearby lightning strikes (ask you neighbors if they have every suffered any losses from storms), then take the time to do it right with shielded cat5 cable, a good ground, and adequate surge suppression.
A good link on why shielded cat 5 is here:http://www.belden.com/pdfs/Techpprs/...ghEnoughtp.pdf
Especially scroll down to the part about EMI/RFI; although they do not specify lightning directly, actually lighting is form of EMI/RFI-just a REALLY POWERFUL version of it.
Everyting you wanted to know about grounding and suppression:http://www.polyphaser.com/technical_notes.aspx
I hope this boring rant helps someone out there!