Thursday, May 8, 2003

Woke up this morning and my dog had split open her stitches to leave an inch wide gaping wound in her hip (fortunately, no blood)....

... and then discovered that a lightning strike near the house was enough to take out at least several ethernet ports on random devices and my broadband connectivity. Not sure what else yet -- always hard to tell. I'm generally proactive about unplugging devices in the presence of an electrical storm. This was one of those annoying bolts from the blue....


So far, the lightning strike negatively impacted:

  • Linksys DSL/Cable Router: doesn't do DHCP on the WAN port, 2/4 ports blown.
  • Linksys 5 Port workgroup hub: 2/5 ports blown
  • Dual Proc 450mhz G4: Ethernet port blown (fortunately, it has an airport card in it)
  • Motorola Cable modem: Dead ethernet port (fortunately, Cablevision replaced it with absolutely no hassle what so ever -- they rock!)
  • TiVo series 2: Dead modem (common problem -- fortunately, the last successful call had upgraded the TiVo to support USB<->EtherNet devices and I should be able to drop one in without having to deal with replacing the modem)
  • Garage Door Opener: one of the "oh crap! something under door!" sensors seems to be locked into "Oh crap!" mode

I have cobbled things back together, but I'm sure there is still some undiscovered pockets of entropy ready to cause a bit of hell.

What is truly frightening is that this is the second time my home LAN has been wasted by a "bolt from the blue". The first time was in Chicago -- took out an ethernet controller on an HP-PA RISC box, a hub (it went insane-- plug it in and it'd happily route ghost traffic all day), one serial port on my NeXT cube (but nothing else), and a Fax modem.

This is actually the fourth time I have been within the "blast zone" of a lightning strike. Once, lightning struck a tree about 40 yards away from where I was standing-- I was blind, deaf, and on my ass in a mud puddle in a matter of milliseconds. The other close call hit a tree about 8 feet away from the cabin I was in at summer camp. The tree exploded and little bits of tree guts damaged the side of the cabin and poked some holes in the screens closest to the tree.

So, in case of electrical storms, stay the hell away from me!


A pontification asked if I use surge protection.

I do -- everything is plugged into one or two layers of surge protectors. But even the best consumer surge protectors are relatively useless in the face of a lightning strike.

There are two key problems.

First, a lightning strike is comprised of one giganormous bundle of energy released all at once. We are talking about a really stupid-large amount of volts/amps. Weird energy levels-- as in "when that much energy is released in one spot, weird stuff happens".

At high energy levels, electricity changes in nature. In particular, air conducts electricity while metal will actually act as an insulator by comparison. However, as the electricity passes by metal objects-- especially long pieces of cable stuck on poles, etc-- it will will tend to induce a current/voltage spike on that metal. A really huge spike.

When such a spike-- either directly or indirectly from the lightning-- hits the surge suppressor, there is generally enough power to "route around" the suppressor. Boom. Dead equipment.

This is why you should always unplug equipment when an electrical storm is passing through. The world's best surge suppression-- even though so called "lightning suppressors" isn't going to do jack in the face of a full on strike.

Given that none of the equipment in my house that is connected to only power or to just power and phone is damaged, it is much more likely that the bolt hit somewhere in the neighborhood and I'm suffering from the following.

The second major vulnerability with lightning is conductive paths that are not surge protected that lead to relatively sensitive equipment.

Given that the cable modem is dead, the router hooked to the cable modem is dead, the hub connected to the router is dead, and a computer connected to the hub is dead but none of the phones, nor the fax machine, are dead, it is likely that the lightning came in through the cable line.

Since the cable line comes in through the garage area of the house, that may be the reason why the garage door has gone on the fritz. Remember -- lightning is very weird.

Unfortunately, cable lines also appear to be fairly good inductors for lightning. That is, lightning passing near will induce a big spike onto a cable line quite efficiently. So, I have heard. Given that my garage door opener is acting wonky, I'll climb up on the roof tomorrow and see if I can actually spot damage.

The TiVo probably died because it is connected to the cable through an analog (relatively bullet proof) cable box (common ground) and directly to the telephone line. A standing complaint against the TiVo hardware is that the modems fry in the presence of even minor disturbances-- acting as a conductive path between the cable line and the phone line for an induced lightning pulse is certainly somewhat beyond your "minor disturbance".

Lightning is powerful, scary (and deadly) and surprisingly weird. It often kills livestock.

The national weather service has a great site about lightning.

Ball lightning is the grand-daddy of weird electrical phenomena. It is quite likely that ball lightning has contributed to a number of myths over the centuries.
10:14:24 AM  pontificate