I stopped offering TVSS devices as a product to push for sales.
The reason is simple, liability, too many will blame you if and when there house gets hit by lightning and equipment still is damaged, while their homeowners insurance will in most cases pick up the bill for the damage, I don't like to push something I can not guarantee will work, I do believe in TVSS and have many in my house, but I also know that they can be a false sense of security that many hang there hat on as the protector of everything, and when they find out that they can and will still loose equipment in a lightning strike they will come looking at you to pay.
One of the reasons they will not or can not always protect is EMF, the amount of EMF produced in a lightning strike is tremendous, and lightning doesn't even have to hit or conduct to the building to damage the equipment inside, and in fact most damage by lightning is caused by this as a near field strike, trees are the most struck things on Earth and in some cases are used with the intent of drawing the lightning to them (Blue Spruce) but the EMF will still be induced into the wiring runs in a house including cable network and phone lines, and this is where the problem of protection lies, this field of EMF will treat each cable as one turn of a transformer, the whole cable not just the hot or neutral, the voltage potential difference will be between two sets of cable and the equipment that has both these cables run to it, a TV with power and coax, entertainment center fed from two different circuits like when you put a powered sub across the room, a computer with wired networking telephone line to it also, these are some of the examples that are mostly damaged in a near field strike but are not limited to them, you can have both direct strike voltage and near field damage all depending where the point of attachment is.
Lightning is a high frequency event that is still not fully understood, the induced current that near field strikes put into cables is like a transformer, the secondaries are a new derived source and no longer reference Earth as a return path, this leaves nothing but circulating currents within these conductor loops between equipment to do its damage, and since most all TVSS devices only protect between individual conductors in a cable not between different cables as a whole, they do very little to protect against the damage.
True lightning protection starts with the installation of the very first wire or conductor in a building and is adhered to from the ground up, wires ran in single pathways only branching to devices, avoiding loops is just some methods to offer, I don't discourage TVSS usage but when they do want them, I do it with educating the buyer on it strong points and its weakness on paper and verbally, and put a well written disclamer that it will not protect from lightning in every instance.
Ok book done
