Aug 17 2010


It’s not good when you wake up in the morning after a bad storm and discover that your computer won’t boot up. But it’s really bad when you find that the other computer won’t boot either, and then when you pull your 10-year-old third-string backup system out of the garage so you can get online with a text-only browser and at least get some troubleshooting documentation, you realize your router and cable modem are both dead to the world. That was my Saturday morning.

At first I thought surge protectors must be even more useless than I guessed — how much protection can a $9 piece of plastic from China really give you from a million-volt attack from the heavens? — but it looks like it came in through the cable, after hitting the pole in the alley. Of couse, that’s the one place we weren’t protected. So far, the damage is:

  • System 1: power supply and the on-board Ethernet interface (which makes me wonder how much I can trust the rest of the motherboard now).
  • System 2: motherboard at least. Fortunately, we were planning to replace this system soon, but not last Saturday.
  • Router: The two Ethernet ports our PC were plugged into seem to be dead, but the other two and the wireless still work, so that might be okay for now. (Actually, the wireless was working at first, and then seemed to quit, so the router might be on its way out.)
  • Cable modem: Dead. And a new one couldn’t make a connection, so we had to wait until Monday to find out the problem started out at the pole, and get that fixed.

The only bright spot is that we didn’t lose any drives, so there’s no data loss. We keep good backups, but restoring from backup is still a pain.  I was able to get System 1 running with a borrowed power supply and an old network card.  Parts for the new system are on the way, soon to be followed by a UPS with cable protection. I guess that’s one advantage to having a wireless home network even if you don’t need it: power surges don’t travel across wireless. That introduces security and speed issues, though, so I still like wires.

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  • Jason says:

    What most people don’t know is that just because a power strip claims to have surge protection doesn’t necessarily mean that it’s going to do any good. Many older houses, even though they have 3-prong outlets, don’t really have those outlets grounded. They replaced the original 2-prongs with 3-prongs, but kept the old wiring that didn’t have a ground wire. Sometimes people ground the outlet to the gang box, but since the gang box isn’t grounded, it doesn’t do any good.

    Even if the outlet IS grounded, the chance that it’s WELL grounded are hit and miss. Most houses have a single ground rod at the meter. That ground rod was probably never tested to make sure it was a good earth ground. In fact, ground rods gradually lose conductivity on their surface over time, making them less effective. Ground fields around things such as microwave towers are tested periodically and replaced when deemed ineffective.

    Also, suppose all the grounding in your house is perfect, and you’re ready for the next lightning storm. But, the cable company has a poor ground on their system where the cable leaves the pole to come to your house. The lighting pulse may enter their system but see your AC ground as a better path and go through your equipment to get there. There are standards for all of this stuff, such as bonding grounds together within a certain distance to prevent a difference in ground potential, but many times the standards aren’t followed. For instance, my telephone demarc has a ground wire that goes through the wall and is bonded poorly to my water pipes. My electric ground is on the opposite side of the house, with a single ground rod. I’ve been lucky – which reminds me that I really need to fix that.

    And lastly, even if you’ve done everything you possibly can to protect yourself, there’s always inductance. A lightning strike can induct voltage on wiring, such as cat5 ethernet cabling, and wipe out ports on your equipment. I know of a strike recently that apparently inducted on some 50-foot serial cabling, killing the ports on both ends, but damaging nothing else in the entire building.

    Lightning is a strange thing. Completely unpredictable, it can do some truly bizarre things.

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    • Aaron says:

      As it turns out, the cable wasn’t grounded at all, and that was definitely the path of the damage, from scorch marks on the pole through the modem, router, and network ports, all toast.

      Although it looks like they weren’t the problem this time, we’re going to replace the power strips with something more serious, maybe UPSs. Something that will tell us if the outlet isn’t grounded well (or at all), and that we can run the cable through too.

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