Lightning-What Got Hit?

[OnesNZeros]

Was looking out the window this afternoon and thought I saw a skinny bolt of lightning hit my pool. Wasn't sure, the thunder was instantaneous but surprisingly quiet, and when nothing seemed to be wrong with the pool's electrical, I figured I'd been seeing things.

Several hours later, it's clear we were hit *somewhere* I just don't know where.

- we have two computers, a Dell PC upstairs, intenal modem, and a Mac downstairs, external modem. Both modems are fried, though nothing else seems to be wrong with either CPU.

- A 75w incandescent bulb in a ceiling fan light blew while it was on. (upstairs)

- Both battery powered thermostats (up- and downstairs) reset themselves. The A/C compressor runs outside, but the fan/blower in the attic does not, so of course we have no A/C. (Some ice caked on compressor pipes.) No breakers were tripped.

Could this have been some forked lightning bolt that got my pool AND something on my roof? (The phone module out in my front yard show's no obvious sign of a lightning strike.)

Thanks in advance,

1s&0s

[thunder]

Over the years, the house I live in has had over twenty near hits, so I've noticed a few things. First, what you saw hitting your pool, may not have been lightning. It may have been an upward streamer. I say this because any near strike, I have witnessed, is exceptionally loud. I *believe* I have heard streamers immediately preceding a strike, sort of a phhhtt before the big ka-boom. ;-) Don't get me wrong, you could have been hit, or it could have been very close with the power surge following your lines into the house.

I had a whole house surge protector installed, and it seems to have protected my appliances, but I have found answering machines and modems are the most sensitive to the electrical surge, having lost several of each. I had an old style fuse block on the phone lines. After a close hit, the phone guy replaced it. He seemed quite impressed. All the lines had blown off of it. The replacement seems to work better, as I haven't lost anything lately, but then, if I am around, I unplug.

[Joseph Meehan]

It may have hit the pool and that could have caused everything you noted.

Lightning has a mind of its own and is not predictable.

[Ron Hardin]

Very close strikes don't make much noise - the bang goes to the side in the far-field.

Phone-line things get fried because they see a ground loop usually: ground is at various voltages in various systems, extremely so when lightning hits nearby, and if you have two systems coming together like phone-ground and power-ground, the card that combines them gets fried.

On a normal day, if you drive two ground stakes into the ground say twenty feet apart, you can measure about a half volt (AC) voltage between them. Ground is a matter of opinion, so you want only one.

If you're serious about lightning protection and money is no object, you can do it. For most people replacing the cards occasionally is cheaper; and unplug stuff that matters when there's a really active storm going on, if you're home and handy.

[OnesNZeros]

STREAMER. Yes, I *knew* there was a name for "skinny/quiet bolt of lightning"! Thanks, and yeah, that's what I think it was. There was far more lightning going on than what we usually get during a typical t-storm around here, but still, there was never any really loud thunder when we got hit this time.

What's weird is I often (say 60-70% of the time) logoff/shutdown/unplug when lightning's afoot, but didn't this time. But, I've never unplugged phone lines because, idiotically, it never occurred to me that lightning would get the phones. So I guess this was bound to happen. (But then, was it? Could lightning go up the phone lines and fry the modems even if every device was unplugged, but the modems were still connected to the phone lines?)

Thanks,

1s&0s

[w_tom]

For some reason, your phone line is connected to an earth ground that may be better than earthing of the pool. Phones, CATV, and AC electric must enter a building at the same location - all earthed to the same common ground. But, for example, if your phones are earthed somewhere else, then lightning had a better path to earth ground via AC electric, incoming through modems, and outgoing through phone line ground. Notice how modems are usually damaged and notice that the complete circuit must first exist. Incoming is most often on AC electric - a direct wire connection to both modems. Outgoing to earth ground via phone line.

The concept of central earth ground is demonstrated in these figure:

To better understand how the damage happened requires understanding of the complete electric circuit that entered via pool and exited elsewhere through house. All damage was avoidable. Pulling plugs for every storm is seriously unreliable (after all, one is rarely available 1/3 of the time to perform the task). Furthermore pulling plugs for every storm may create plug intermittents. Plugs also have a life expectancy.

I gather you had no 'whole house' protector on AC electric. If you had, the transient that entered house via pool's AC electric could have been earthed right at that breaker box. Destructive surges occur typically once every eight years. But since 'whole house' protectors are so inexpensive, then value of such protectors is probably the best lesson learned. Damage from such CG lightning strikes is always avoidable - especially if you learn from previous experience.

Home Depot sells two minimally sized 'whole house' protectors - Intermatic EG240RC or IG1240RC or Siemens QSA2020.

[JNJ]

What's unfortunate is that many folks do not consider the fact that wires connect various PC devices and a strike will course over all wires. For example, one of my clients has a couple dozen PCs with printers connected to each. They're VERY attentive to backup power supplies (UPS) and surge protection for their equipment -- PCs, monitors, and even telephone lines in some cases. However they never put the PRINTERS on surge protectors. Printers typically connect to PCs via a parallel cable. They were hit with lightning a couple of weeks back and the printers took the surge and blew...as did every parallel port in the place. Their servers, which sit side-by-side, have a quarter-size black dot on the surfaces that meet -- this is where the charge arc'd between the metal cases. Luckily, by the time the charge made it to and through the parallel ports it was fairly weakened -- most of the systems did not suffer any further damage.

The same goes for telephone lines, networks, DSL/Cable or any other wired connection.

Interesting anecdotes from the computer sector. :)

James

[Gary Tait]

I've had may modem hit by lightning before, and managed to repair it fine (the on hook SSR got blown twice, replaced with a mechanical relay). The last time was unrepairable though, fourtunately the modem I bought through an E-bay auction arrived the next day, and am using it now.

[Sparks]

I wonder how many 8 year old PeeCee's are still around...

Semper Mac.

________________________________

Remove S.P.A.M in email adddress Climb mac com ________________________________

[Betsy]

Having been hit by lightning once, I can tell you I heard nothing (actually I was under a tree where it hit, but I watched the spark jump between my hands). Of course I was screaming so loud I don't know if I would have heard anything. It was quite an experience. I "knew" it was about to happen a millisecond before it did.

Anyway, it wasn't loud.

[JNJ]

Gots a bunch of 'em upstairs, although the oldest one I have in service is 5 years old. :)

Hmmm...I suppose I could toss Linux on any one of 'em and run circles around most Macs.... :-P

James

[w_tom]

Once lightning is permitted inside a building, then everything is susceptible to damage. Common mode signaling, such as on printers, may be most easily damaged. Not because they are missing plug-in protectors, but because they use a different connections to AC mains AND use common mode signaling.

Example of such difference is that arc between server cases. Arcing would be part of a circuit that conducted electricity to earth, then increased that current to cause damage. Just another example of why surges must be earthed before entering a building. Damage that will appear to be random until the circuits are understood. Damage that occurs from so many different sources and directions inside a building. Effective protection must be at the service entrance using single point ground - the most critical component in protection.

Surge not earthed before entering the building, typically, will cause damage as has been repeatedly proven even since the

1930s. Once inside a building, the destructive transient will find every path to earth; even through material not considered conductive such as linoleum tile or concrete floor. Some appliances may be damaged while acting as a surge protector. However too many generations of experience AND fundamental theory have demonstrated that effective protection is earthing a surge before it can enter the building. Such protection tends to cost 10 to 50 times less per protected appliance.

JNJ wrote:

[Gary Tait]

One right beside me, haddrive going is about it's problems right now.

[barry martin]

Hi 1s&0s!

O > Was looking out the window this afternoon and thought I saw a skinny bolt o

O > lightning hit my pool. Wasn't sure, the thunder was instantaneous but O > surprisingly quiet, and when nothing seemed to be wrong with the pool's O > electrical, I figured I'd been seeing things. O > O > Several hours later, it's clear we were hit *somewhere* I just don't know O > where. O > - we have two computers, a Dell PC upstairs, intenal modem, and a Mac O > downstairs, external modem. Both modems are fried, though nothing else seem to O > be wrong with either CPU.

You were lucky only the modems were damaged! Surges from lightning can enter along the telephone and cable/satellite wiring. Would be a good idea to put some sort of a surge protector on those at the entrance (demarc for the telephone, first splice for the coax). W_Tom and others (including myself so a much lesser extent) have previously posted on surge protection 'policies'.

O > Could this have been some forked lightning bolt that got my pool AND someth ng O > on my roof? (The phone module out in my front yard show's no obvious sign o a O > lightning strike.)

The damage may have been from the one streamer you saw, or could have been from a strike miles away. Years ago I was talking with my parents when there was a lightning storm appoaching, probably 5 or 6 miles from here. Thought a fly was landing on my ear (the one to the handset), few seconds later heard a distant rumble. Finally dawned on me I was being electrocuted! Unplugged the phones at the demarc; got and installed a surge protector. No "flies" since then! (And no, the best surge protector in the world isn't going to protect against everything, but better than nothing.)

- ¯ barry.martinþATþthesafebbs.zeppole.com ®

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