Well, it's that season again. Electrical Storms.

For years, we've encouraged people to UNPLUG their modem from the phone line while not in use. Unfortunately some inexperienced users forget, and some consider it inconvenient to do so. And every time there's a decent storm, we have a new wave of people who learn from their mistakes. The storm on the evening of August 21st was no exception. Thousands of dollars worth of customers modems and computers were destroyed that evening.

ALL were avoidable losses.

Little, if any, will be covered by insurance. None of the modems, many less than 3 months old, will be covered by warranty. If you check the fine print in your modem manual you will most probably find electrical damage (spikes, storms etc) are specifically excluded from warranty claims. Your household insurance may or most likely may not cover storm damage to your modem or computer.

Reprinted here again for your information are articles from past newsletters on the dangers posed by electrical storms:

April 1997

Reprinted article:

Autumn...
... is already on us and Winter is coming up FAST. With the change in seasons comes an increased risk of thunderstorms, and with that an increased risk of lightning damage to any appliance connected to power and/or phone lines. This includes your computer and modem. Modems are in fact doubly at risk, they can be damaged by a lightning induced spike from either phone lines or power lines, and if your modem is internal ... you can kiss good-bye to your computer too!

The high voltages induced (see the Sparks Flew article for technical details) can jump the small gaps in your power points, even if the power point is turned off! The only surge protectors that will protect against this type of induced spike generally cost more than the equipment you are trying to protect, and NOTHING will protect you against a direct strike.

The only way to prevent lightning damage during thunderstorms is to disconnect your computer, monitor, modem, (in fact any appliance that it would really bug you to have blown up!) from power and phone lines for the duration of the storm. And remember, don't use the phone yourself unless it is a cordless variety or mobile.

We recommend disconnecting modems from phone lines at all times when not actually in use. It may seem inconvenient, but lightning does not always give a warning, and is not the ONLY thing that can cause spikes - magpies shorting out power lines, vehicles running into power/phone poles, the handy(person) next door using an arc welder etc etc etc ...

What happens and why:

Also reprinted from the April 1997 article:

April 1997

And the sparks flew ...

Lightning is pure plasma. A lightning strike to ground produces two destructive effects:

1.There is a massive magnetic pulse, which induces a high voltage spike in nearby conductors (wires) - phone or power cables etc.

2.The second affect is the "ground potential" where there can be massive potential differences from one "earth" point to another. If your house electrical system is earthed locally, and a lightning strike occurs nearby, your "earth" may be several hundred (or thousands) of volts different to the "earth" at the phone exchange, or nearby electrical substation. These potential differences can (and will) exceed the ability of the insulation in power supplies, transformers and other isolating devices to withstand, and destructive currents can flow. "Surge protectors" are largely ineffective against these voltages and currents.

And again in December last year:

Reprinted from the December 1997 article:

December 1997

Yikes!! mind the storm damage...

With the storm season here, it's topical to remind subscribers of impending storm precautions (also refer to our April 97 issue):

Disconnect modems (particularly) from phone lines during storms (it's good practice to disconnect them when not in use anyway)

If a particularly severe storm is pending with lightning strikes and strong winds likely to bring trees down over power lines, physically disconnect computers and modems from power points as well. Just turning them off may not protect you - spikes can jump inside switches even if the power point is turned off! Pull the plug out of the wall socket. Spikes can kill your modem and your computer!

Don't use the phone yourself unless it's absolutely necessary, and then preferably of a cordless variety. Spikes can kill people too!