Satellite Retailer Magazine October, 1996 Issue REPRINTED WITH PERMISSION	RICHARD MADDOX

Conventional wisdom says that big dishes attract lightning, but small DBS dishes don't because of their size. It sounds good, but experience over the past year tells otherwise. Dealers in Florida know that when it comes to lightning surge damage, neither system is immune. And they should know since central Florida is the lightning capital of the U.S. In an average year over 100 people are killed by lightning in the United States. This is far more than are typically killed by the more high-profile natural disasters like tornadoes and hurricanes. Lightning is also responsible for up to $1 billion in property damage each year, which certainly includes thousands of home satellite systems being taken off the air.		It seems that the only good news about lightning is how easy it is to protect yourself from harm. The main rules: get inside a structure -- a house, garage or even an automobile or truck will provide sufficient protection from the danger·s of lightning, but while there don't touch anything connected to the outside world (especially a wired telephone, anything plugged into the electrical system, or the home plumbing system). The reason is that the electrical current travels around the outside of the structure looking for ground and you're only in physical danger when that current has to pass through your body on its way to ground. Since lightning often enters a home through the telephone line, your only avenue of protection on a phone system is using a cordless or cellular phone. And since water pipes are grounded (and are often used as grounding points), you also have to be careful about washing your hands during a thunderstorm since lightning has been known to follow the metal pipes throughout a house, shocking anyone in contact with running water or the water fixtures.

Of course, outdoors is the worst place to be caught when lightning strikes, especially in an exposed situation like a rooftop DBS installation or when replacing an LNB on a big dish. Even seeking protection under a tree is dangerous since lightning loves to use them as ground rods (especially pine trees, which seem to be nature's lightning rods). Common sense would certainly tell you that if lightning is striking in the immediate vicinity to clear the area. The problem is that lightning can travel up to 12 miles from the parent storm cloud, seemingly searching for just the right ground potential, before striking the ground directly or an object in its path to ground. Thus even being on the fringes of a storm may be hazardous to your health.

Although just a few simple rules can keep your installation or repair technicians from getting slammed by lightning, keeping your customer's equipment from being affected is a different matter entirely. Unfortunately there's been a tendency for dealers to treat lightning as a potential income center rather than to offer their customers a measure of protection right up front during the sale and installation. After all most homeowners have home insurance so, for the cost of the deductible, the customer gets a new LNB and possibly a new receiver every year or two, and the shop gets to charge the insurance company full pop on the components and labor. It's a win-win situation -- except for the customer's aggravation on having to wait for repairs or for new equipment. And if the system owner doesn't have insurance -- well such is life. Uninsured dishes that have been hit by lightning may account for many dishes that are now pointing into trees, pointing to the north or into the horizon, or that no longer have feeds on them.

For most dealers, lightning repairs are good for the bottom line since basically they're a matter of replacing whatever component (LNB, feedhorn, motor drive and/or receiver-), or components in many cases "took" the hit. In most instances no thought is given to replacing the cabling, unless it has been literally burned in half and is no longer functioning due to shorts or opens. But what most repairmen don't consider is that by not replacing it they are leaving the system in a compromised condition. This is due to the fact that coax cabling or the shield surrounding Polarotor and motor wires, will become pitted by the high current of a lightning strike. This high current call also form microscopic pits in the insulating material surrounding the cabling which can lead to moisture ingress into the cable. In any case the signal quality will probably be less than what it was before the strike. Thus in every lightning damage service call, replacement of the dish-to-receiver cabling is essential to ensuring the system is back to 100 percent operation.

And if you're in an area where lightning causes repeated widespread damage (Figure 1), not any cabling will do. There's a new type of cabling that is being marketed specifically to minimize lightning surge current flow in home satellite systems. It's called LRC (Lightning Retardant Cable) and it's available for both full-view and DBS versions. The full-view cable is available with one or two RG-6 coax cables along with an assortment of motor and Polarotor cables in a single fully shielded cable. The DBS cable is a single RG-6 type of coax that is also fully shielded.

Figure 1: Isokeraunic levels across the United States

The main difference between LRC and standard satellite ribbon cabling is in the added shield and drain wire. In the standard satellite ribbon cable used with home satellite systems there is no drain wire on the coax; there's only a drain wire on the motor and polarizer wires (if you're lucky). On the LRC cable there is a thicker shield that is wrapped at a precise 45 degree angle counter-clockwise around all the wiring. On top of this shield a drain wire is wrapped at the same 45 degree angle, only in a clockwise direction on the cable. The drain wire placed on the outside of the shield serves to minimize the magnetic component of the lightning surge through its winding method while carrying the high currents to ground.

The LRC cable design has received patents from the U.S. and Canadian governments. The master distributor for LRC throughout the world is Protective Wire & Cable, who markets it through various satellite equipment distributors in the U.S. and Canada. Dealers can contact Protective Wire & Cable for distributor information. In the U.S., consumers can order the cable directly from Consumer Lightning Products if there is no local dealer carrying the product. Consumer Lightning Products also has an Internet website which both dealers and consumers can use to get more information about LRC (address and contact information is at the end of the article).

LRC is manufactured in Canada by Deca Cables (a large manufacturer of ribbon cable). Starting life as a standard ribbon cable that is folded over and then wrapped with the extra shield, and a drain wire, LRC ends up a round hose type of cable. But, once the outer shield is stripped back, the standard ribbon cable within is ready to be connected. The suggested retail price is $1.50/foot for the single RG-6 fullview cable with motor and polarizer wires. The cabling does come pre-fitted with F-connectors and weatherboots and with wire nuts for the signal wires.

There are four places where a home satellite system (regardless whether it's a full-view or a DBS system) is vulnerable to lightning surges:

1. The cabling from the dish.
2. The power company lines.
3. The telephone wiring.
4. The cable TV or off-air antenna wiring.

Each of these locations can allow damaging lightning voltage surges into the delicate electronics of a satellite receiver. To counteract these lightning surges a combination of grounding and surge shunting is typically employed. The first problem can be minimized by using LRC wiring that is properly grounded at the dish and at the cable entrance to the home. The second, third, and fourth problems are typically minimized through the use of surge protection devices. Unfortunately, the most common surge protection technique uses Metal Oxide Varistors (MOVs) or trans-zorbs (fast reacting avalanche diodes) to divert any high surge voltage to ground. These devices are found throughout home satellite components: LNBs have them across the inputs of their voltage regulators; the dish wiring inputs (for the motor and Polarotor wires) have them tied from the various lines to ground, and there are MOVs across the AC input to the receiver's transformer as well. They are also the most common components used in commercial "surge suppressors." Figure 2 shows how most "garden-variety" suppressors work. MOVs are typically placed between the hot-and-neutral and hot-and-ground wires and serve to shunt the power line surge into the neutral and ground. Because MOVs react slower than the rise time of the lightning surge, some of the lightning energy gets through and into the power supply of whatever component is being protected. Trans-zorbs are faster than MOVs, thus reacting quicker and stopping more of the surge, which makes them a better choice. Another upside of trans-zorbs are that when they fail they typically short. Of course they have also been known to catch on fire while doing their job, and they cost more than MOVs, so all is not rosy with trans-zorbs either.

The basic problem with all MOVs and trans-zorbs is that they are really sacrificial components that are designed to take the brunt of the voltage surge by shunting it off to the neutral and ground wires. Unfortunately, every time they do shunt a spike or surge their integrity is compromised (sometimes catastrophically so). Typically their life span is well under two Years of service. And there is no way of identifying -- regardless of how many cute LEDs or protection lights are on the case, when they have actually died, leaving the components they're supposedly protecting open to severe damage with the next surge (unless they short blowing a fuse or circuit breaker).

The only type of surge eliminators that do work on a continuous basis are those that use series mode suppression. This is a patented technology that is available from several companies. Figure 3 shows a series mode suppressor. In this design the power line is coupled through a large choke (that typically consists of up to two pounds of windings and core). The choke acts as a current limiter to any frequencies above the 60 Hz line frequency. This then feeds into a voltage limiter containing a storage capacitor that is used to drain off the surge energy into the neutral line rather than into the receiver's power supply.

An additional advantage to the series mode suppressor is that it does not dump surge currents into the safety ground like shunt mode suppressors. This is why external components (like feedhorn motors and LNBs) are often damaged, yet the receiver is not damaged, even though a "surge suppressor" was being used. Because the components in a series mode suppressor are designed to handle the large surge currents safely, their life spans are typically more like that of the components they protect. (One manufacturer even offers a 10-year warranty on their product).

On coax cables that do not pass DC voltage (such as cable TV and antenna signals) as well as on phone lines, the only viable surge stopping parts are MOVs, trans-zorbs, and gas discharge devices since there are no series mode suppression devices. In this case having marginal protection is better than having none at all.

Since lightning very rarely directly strikes a home satellite dish, lightning damage is typically not a spectacular sight. Very rarely are dishes blown apart, receiver face panels tossed across the room or TV tubes imploded (not that any of these hasn't happened). Often the only noticeable sign that anything has been destroyed (beyond the obvious no picture or sound problem) is the acrid smell of fried electronics components. And hopefully the only components that are fried are the MOVs and trans-zorbs rather than the receiver's components.

More commonly lightning enters a home through ground induced current flow into the dish cabling from a nearby lightning strike or into the home through a spike on the phone or power lines. Thus for complete lightning protection both avenues of ingress must be locked shut, which is where LRC cabling and series mode surge suppressors come into play. When installed on a properly grounded system, there is no need to fear Mother Nature's light shows -- as long as you watch them from indoors.