THE EFFECTS OF LIGHTNING
On Home Electronics
These are the facts about lightning and electronic home devices like Webtv & PCs, televisions, phone answering machines and other electronic devices from an electrician...me.
The first thing to know is that a surge protector, or shutting your equipment off isn't going to make the slightest difference if your house or the electric drop or phone line outside is hit by lightning. If you house is wired properly, then the lightning current will travel down the service drop to the service panel where your electric meter is. From there, it should go down the grounding cable and into the ground and not into your house. If by chance, you don't have a good ground on your service panel then the current may go into your house. This current is of such a high voltage that it will simply arc right through your surge protector burning it out completely and do the same to anything connected to it. It only takes a fraction of the voltage contained in lightning to arc across the surge protector or the contacts of any "on/off' switch in a device and burn out the circuits. Shutting your Webtv box and other equipment off won't make the slightest difference. The box is still on anyway, even when you've shut it off. Only a part of the circuits in the box are shut off, otherwise, you couldn't turn it back on with the remote or keyboard, it is simply in standby mode.
If your electric service is not properly grounded, and sometimes, even if it is, and lightning strikes it, you can count on lots of blown out light bulbs and burned out electronics in your house. Lightning rods are very helpful in areas prone to lightning and will direct the strike away from your electrical circuits.
The other risk to your Webtv box or computer is the phone connection. Phone lines are not grounded and if struck by lightning will carry the full charge through the lines into your house if the strike is on your phone drop or pole. There is more risk of damage from a phone line strike than there is from an electrical drop strike, but the odds are that the strike will more likely hit the power lines than the phone lines because they are always higher on the pole and have more conductivity. Unless, of course, your electrical feed comes from underground and the phone feed doesn't. If your phone line is struck, then the current will pass through the line, arcing through your Webtv box or computer, to the electrical cord connections, down the electrical cord to the wall socket and through the wiring conduits, back to the panel when it will then find the ground cable and go to the ground. Your Webtv box or computer and surge protector have both been fried in the process. Your best defense if you think you may be hit by lightning is to unplug all connections to the phone jacks at the wall until the lightning passes. If you're not sure about the condition of your electrical system or that it is properly grounded, unplug all appliances during a lightning storm and have your house wiring checked by a licensed electrician.
Surge protectors are a good idea too to suppress any inductive surges caused by the lightning strike, just as long as the actual strike doesn't pass through the surge protector. TV cable service has the same risk as phone lines but to a lesser degree because they have a grounded shield in the cable. Modern telephone terminals and demark boxes on your house will also be grounded but the actual phone conductors are not and are unshielded.