Lightning Strikes Thrice

I used to be so naive about lightning. Of course, a direct strike could be catastrophic. Ignoring that, I assumed the main vulnerability of electrical devices is surges on power lines – if power wiring had enough surge protection, then things would be OK. About a decade ago I started thinking that phone lines needed surge protection, which they do. The last year has made me realize that just about any kind of wiring and device is vulnerable to static electricity damage from a nearby strike. This seems to be particularly true of Ethernet (10/100/…BaseT):

In April last year a strike near our house disabled two ports of an inexpensive Ethernet hub. It was puzzling at first, particularly since out of couple of dozen ports cabled at the time to more expensive devices (computers and routers), there were other ports that I thought more susceptible to static buildup. (Those thoughts were based on cable length, location, etc.)

In August last year a friend’s SUV took a direct strike while parked in front of his single story office building. This was on flat land with tall trees and multi-story buildings next door and across the street. Go figure! About half a dozen seemingly random Ethernet ports, out of about three dozen in his building, were taken out.

Then last month a new level of realization and respect “struck.” A major bolt devastated a house somewhere near here, but not near enough that I’ve seen the direct damage. The indirect damage, at our home alone, was extensive, and seemingly random. In approximate reverse order of discovery:

The (electro-mechanical) timer for the pool pump stopped at the time of the strike, presumably because of the surge on the power line.

The thermostat for the smaller floor HVAC got scrambled enough to run the compressor constantly, even when the thermostat was turned off entirely.

The alarm system siren announced that a burglary was in progress, even though the alarm system proper seemed undamaged afterward. (A prior alarm system was much more susceptible to static damage, with the main system board twice succumbing to nearby strikes in the 1990s.)

The phone line was dead (on SBC’s side of the “demarc”). (This was probably part of what upset the alarm system.) A phone and the surge protector for the alarm system phone line were also fried.

By far the most expensive damage was a Dell 2450 that I consider a total loss. (Four years ago, that machine cost about $17K.) I assume the damage was due to whatever came in the Ethernet port, since the power line was very well protected by a UPS and other devices with the same protection were unharmed.

Many Ethernet ports were damaged. Fortunately, except for the 2450, these were inexpensive to replace.

Unfortunately, I have only a few lessons learned to avoid a repeat experience:

  • Put power and phone protection everywhere.
  • Leave anything unconnected that doesn’t really need to be connected.
  • Use (inexpensive) extra Ethernet switches next to expensive devices, simply as protection. Much better to lose a $20 switch than an expensive computer.
  • Think of Wi-Fi as a way to avoid static electricity damage.