Friday, August 2, 2019

My Turn for a Bad Lightning Strike

On Wednesday, fellow Florida blogger Divemedic said that his house had a lightning strike on July 30, just one day short of one year since the last time he was struck.  I honestly don't know where he lives with respect to me, but I believe he has mentioned being closer to Orlando and Orange County which are north and west of me.  Closer to the actual lightning capital of the US.  I live on the east coast of the state, south of Cape Canaveral.

In this graphic, I live where the light blue and green areas converge just south of the bump on the middle of the east coast.  Call it 15-20 "flashes per square mile per year" while I think he's in one of the red or orange areas (25-30).  Like all statistics, those numbers never apply to the individual.  When you're number's up, your number's up.

Our number was up yesterday.  Early after sunrise (which is around 6:45 EDT) and not quite out of bed yet, we had an enormously loud crack of thunder.  Startled awake, I looked out of the bedroom window and thought that for a second I saw a glowing red ball in the air, as is sometimes seen immediately after a lightning strike in the super heated air the lightning blasted through.  As seen in this photo, taken from a now-unavailable ten second video I linked to in May of 2015.  I dismissed that as probably impossible - I've become less sure of that.

It wasn't until we got out of bed 10 or 15 minutes later that we realized we had been struck.  To begin with, there are three clocks close to our room; all three had been reset to midnight and started over.  Here's the weird part: one of those clocks is battery-backed up to keep time through a power outage.  Here's the exceptionally weird part: the other is battery operated (no power line) and one of those so-called atomic clocks that gets time sync by radio (no external antenna).   It's not just one.  Another battery operated atomic clock in our guest bathroom also reset to midnight.  This sounds more like EMP stuff than lightning strike.  Has anyone ever seen a battery operated clock get reset by nearby lightning?

I've heard that lightning strikes are capricious - the damage seems to jump over some things to  damage another.  In the next room over is another battery operated atomic clock - it was unchanged.  We still don't know all of what was blown up, after a full day of combing the house, but damage is scattered throughout and in all rooms of the house.  On this computer desk are two desktops with 23" monitors.  One monitor blew out, the other monitor, virtually touching that one, is fine.  Both computers survived.  Also on this desktop, our internet cable modem and WiFi router were destroyed.  Since we stream TV services over the internet, our TV was out.  (Once again, we told each other if we had VOIP phone service we'd be 100% cut off from the outside world)  A couple of the house's circuit breakers were thrown but power came back OK when they were rest. 

Our central air conditioner's thermostat, mounted about 30 feet from the indoor air handler unit that it's wired to, blew out.  We have two model years of some wireless (2.4 GHz) remote telephone handsets.  One of the system bases and its wall wart power supply were blown out while the other set is fine.  Our hot water heater has a remote control head, again about 25 feet from the water heater that it's wired to, that was blown out.  The water heater (a tankless, gas fired water heater) is mounted outdoors and plugged into a weather resistant, GFI-protected, outlet outside.  The outlet was blown up - it wasn't possible to reset the GFI.  We replaced the outlet and once plugged in, the water heater seems to be running normally.  Without a control panel it defaults to 120F water and that's fine for a couple of days.  Ordered a control panel today to be here by Tuesday. 

All around the house, things are plugged into surge-protected outlets.  The router and cable modem that blew up were plugged into a surge protected strip.  What seemed to matter was long wires to act as antennas to the induced electric fields from the lightning.  A variable that complicates that conclusion is how susceptible the thing is by itself - we can hardly ever know how susceptible the thing is.  For example, we have an exercise bike that runs on a 9volt wall wart.  That 9 V supply is plugged into a surge-protected AC strip, but through a 6 foot long extension cord.  The 9V wire itself that goes to the bike is another few feet long.  The 9V supply blew out.

If you looked at our house for lightning targets you'd focus on my ham tower and the oak tree that has almost overgrown it.  It's possible the tower got hit, although I see nothing obvious.  My radios are working, but a central part of my station (and the most expensive part) is apparently at least partially blown.  It won't turn on.  The main HF antenna (a 14-30 MHz log periodic) is acting funny and needs to be looked at with my antenna analyzer, but I couldn't do that because the computer and monitor in the shack both act dead. 

We were able to talk with a helpful and nice kid at our local Staples and upgraded to a combination router and cable modem in one box.  We came home, hooked it up and found it wouldn't work.  We have to call tech support to authorize the modem and the woman I was speaking with said she could get signals from my neighbor's houses but not mine.  A cable company technician was out this morning, came in and found no signal on our cable.  Went outside and found no signal coming in from their closest distribution point.  Came back about a half hour later, after laying a temporary cable from their distribution point to the side of our house.  They have contractors who will be out to bury this one, like the one being replaced. 

I've had lightning damage before, but this is hands down the worst I've ever had.  I've lived in this house since 1984, 35 years, and we've lost a few things to lightning now and then.  A little over 20 years ago, in the days of dial-up modems and bulletin boards, we put in a second phone line for the computers.  We had a nearby strike that blew the phone line junction box off the back of the house, but there was surprisingly little else damaged.  I think some diodes in my antenna rotator control box blew.  Hmm.  Got to remember to check those, too.  I'll be doing this for a while.


  1. My condolences on the equipment loss. I saw the new post, and immediately wondered if your tower got hit, but you'd probably know if it had taken a direct hit by now.

    Generally things disappear from a direct hit, as I've seen happen.

    I've read "Grounding and Bonding for the Radio Amateur" a couple of times now, and I'm going to implement their suggestions to a certain degree.

    1. There's nothing that looks damaged from the ground, however the antenna is acting funny. Once I get the computer going (which makes me a bit nauseous), I need to sweep that thing. It's bad if your 6m antenna sounds better on 20m than the 20m antenna!

      They're separate coax runs and attach differently at the antenna feedpoints but a lightning strike could certainly blow them open. The HF antenna is a T6 LPDA with a toroidal balun at the feed. That needs to be looked at.

    2. I've seen the coax get 'punctured' by the lightning voltage looking for the easiest way out, and the outer jacket get melted from the current flowing in the shield.

      Even if the stroke was couple of hundred feet away, it can induce some hellacious currents in nearby conductors.

      The book I referenced has the "accepted" waveforms and values used to estimate a stroke, and a *low* peak current is 15kA, and the maximum currents are an order of magnitude higher, or even greater.

      When I was an industrial controls Field Service Engineer I used to have to go out at all hours of the day to repair certain critical systems that had taken a close hit. 0000 cable, fatter than your thumb, would get blown apart, leaving vaporized copper and soot all over the place.

      You can't stop a hit, and the best you can do is try to mitigate the damage by trying to keep the energy OUT of the house.

      It's a good book, and considering where you live, it should be on your bookshelf.

  2. Has anyone ever seen a battery operated clock get reset by nearby lightning?

    I once had a battery-operated ultrasonic burglar alarm that had rubber dome switches and no hard power switch. A nearby strike changed it from off to on and alarming. As it was nearly as loud as a smoke alarm and I was sitting under it, this was a surprise.

  3. I'm thankful that both of you are OK, and that damage was limited to stuff.

    As drjim said, "vaporized copper" would have been what I expected to find.

    If we ran your house through the Acme time machine, and set the dial back to 1960, I wonder what the lightning caused damage list would look like.
    Far less electronics, but no surge protectors at all.

  4. We got a lot more lightning over in Clearwater, when we lived there in the 70s. I remember one time where the strike initiated an arc from a neighborhood high voltage line to the ground. It danced around for over a minute (so much for fuses that should have blown). We never had anything actually hit the house, but occasionally (about once per year) we'd lose some clock or a modem.

  5. HA! We just went through another one. Im close...over by FIT and a new lurker. I got hit in the 90's...2 meter Ringo Ranger blown to shards of aluminum all over the lot and the 2M transceiver toast. The tribander was plugged into my 30L1 but since it was old technology I was able to repair (hmmm a pile of there was a component here once). Made sure to unplug everything after that. Now QRT due to age and sunspot cycle and sold all my Collins stuff. Good luck. Syd WB4W

  6. Lightning damage (and all EM induced damage) is all about "loops". A battery powered device can be damaged just as easily as a device plugged into the electric utility.

    Make a loop of wire, pass a magnet through the loop, the varying field produces a current in the loop of wire. Maxwells equations. Lightning just replaces the magnet.

    The more EM field passing through the loop, the more current. The bigger the loop, or the more coils in the loop, or the bigger the EM source, the more current. Also the orientation of the loop matters, the EM has to pass through the loop.

    One clock gets zapped, another is unharmed, the difference can be as simple as how the wires to the battery are run and oriented to the lightning strike, or how the internal circuit board was oriented, or how the cable to the display was oriented.

    I was in a L shaped building, lightning hit outside. All the ceiling lights in the north-south part of the building were burned out, all the lights in the E-W were unharmed. All because of the way the fluorescent light ballasts were oriented.