Lightning Strike Season, or: Weather to Unplug Your Stuff For

Tropical Storm Arthur is on its way up the East Coast as I write this… I’ve already been asked, “Should I turn off my computers when the storm arrives?” And the answer is: OFF isn’t good enough.

Computers draw power when turned off, to keep the clock running. Notebooks pull power for battery charging, all the time. Monitors have fancy ‘soft switches’, which electronically sense a finger press. Pure mechanical switches will actually cut power, but most electronics don’t have them. The front switch on a tower is what we call a ‘momentary contact, single-pole’ switch–it just sends a signal to the mainboard to turn on or off, and doesn’t isolate anything. So turning off a computer isn’t enough. You have to disconnect it from power completely.

How? Quickest way is to flip the small rocker switch on the surge suppressor strip; that should take care of everything that connects to the computer at once. For notebooks, unplug the charger, it’s time to go cord-free.

Same thing applies to all electronics, not just computers. Anything that uses a remote control is connected to AC power, and turned on, at least at a low-power level–unplug it before the lightning reaches your area.

And finally: Remember to also unplug the network cable–half the lightning strike repairs I fix here in Maryland are from a lightning strike at the power pole carrying the Internet into the router, which continues into the network and burns out computers.

Sandy Frankenstorm visits for Halloween

High voltage tower and lightning strikes

As I write this, it’s still around 8 hours before Hurricane Sandy makes landfall on the Mid-Atlantic. Hurricanes, or tropical storms and Nor’easters, can spin up more than just rain and wind. Thunderstorms are likely. A few reminders are appropriate here:

  • Surge suppressors protect your computers and appliances from power surges only if they are plugged into correctly-grounded outlets. Three-prong adapters are not adequate.
  • Surge suppressors protect technology from power spikes that are not extreme. A lightning strike that hits three poles up the street from you will likely be blocked by surge suppressors; a direct hit on the nearest pole, probably not, although on a near strike, a suppressor may still mean the difference between dead electronics and flaming electronics.
  • Cable modems pass surges through on the data line, sometimes without damage to themselves, and will typically destroy the network card or circuit in a computer connected to the modem, along with any router or switch in the circuit. Cable companies discourage the use of surge suppressors on the coaxial cable line–it makes it more difficult for their technology to pass a signal. So a surge suppressor that also protects the network cable, as it passes out of the modem, and before it plugs into a router or switch, is the best way to isolate that electrical path into your computers. I keep these in stock locally, or they’re available here from Amazon.
  • When in doubt, unplug power from computers before a big storm. A computer that’s turned off is still connected to power, and using about 2 watts to power the on-board clock and the electronic front-panel switches. A notebook that’s plugged in will continue to draw power to charge the battery. The best protection is to unplug from power and from any wired networks.

Backup Security: Use At Least Three Devices

321 Backup from Science Translations

Backups are important. But how you backup your computer data is important. A quick reminder: Backup data to three different devices, and place one of them off-site, preferably at a considerable distance.

There are right and wrong ways to do this:

Right: Backup to an external hard drive, an online backup service, and DVDs or Blu-ray disks.

Wrong: Backup to an external hard drive, and two sets of DVDs. That’s three, right?

No, that’s two backups, and none off-site. The flood that you’re tempting fate for will arrive momentarily; move to higher ground. It’s two backups, because the two DVD sets are from the same package of DVD-R blank disks, and when DVD rot makes one useless, the other set will be, too–DVD defects show up by the stack, not just on single disks.

Right: Backup to an external hard drive, a USB flash drive stored in a bank’s safe-deposit box, and a DVD set stashed in a locked garage that’s not attached to your office.

Wrong: Backup to an external hard drive kept in the car, a DVD set kept in the notebook case and ready to head out the door in an emergency, and on a flash drive in the attic.

Nope, that’s no backups at all. The car is no place for hard drives with moving parts, and the attic is far too hot and far too cold for storing computer media of any kind. And that DVD set stored with or near any computer will accompany your computer when the burglar swipes your PC.

Jerry Stern is webmaster at and, runs Science Translations, and is online at