Author Topic: ever seen Saint Elmo's Fire?  (Read 54 times)

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DanG

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ever seen Saint Elmo's Fire?
« on: April 19, 2005, 05:11:32 PM »
To those who have shown off their un-interuptable Power supply projects on Fieldlines, thanks! I caught a 900VA unit for $35USD back in Novemeber, piggybacked it to 32AH worth of batteries, connected everything in my den then completly forgot it untill 9am this morning.


Two weeks ago I posted this comment on fieldlines:

"Thunder from a near miss lightning strike will sound more like a mega-sized pop-top can being opened, a thunderous pop and hissing with alot of the sustained sound being echos reflected back since the sound is heading away from the observer/strike point". I got it wrong, it's hissing THEN thunderous pop!


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We were having a gentle grey and drizzly morning here in Minnesota and I was scanning fieldlines.com as always when out of nowhere I heard soft new-age music atmospheric sound - like perfect silence, utterly masking all other sounds!


I looked past my desktop to the window toward the humming (1920's window glass) when I saw blue-white braids of static wiffling about on my desktop swingarm CFL lamp's coil springs. By that time the soft hissing had grown into a frenzied buzz, there was a soft click and a much louder snap out on the porch and everything in sight went brillant white.


When I could see again, the "getting very cranky" tower post was still displayed on my monitor and the UPS was making that nasty beeping sound - my PC, cat and myself survived a lightning strike.


Looking closer at the lamp showed the modems phone line was about 3 inches from the lamp base & swingarm coil springs.... Why did it had the neon glow?


I'd run a twisted-pair of mil-spec braid shielded line for my den - from the basement telephone companies' junction box to the modular non-wall-plate jack just under the modem, then used the el-cheapo modular patch cord to the EXTERNAL modem. Telco's box I grounded to city water where the 1" copper enters house w/ 12awg solid - and telco's drop line to the house is well shielded and underground since I trenched it in back in 2001.


Why did it had the neon glow? The lamp has a heavy cast-iron weight in the base, the lamp was sitting on two stacked Infinity bookshelf speakers, the speakers were sitting just behind the central air duct outlet, and all this is inside a house that is clad in heavy aluminum siding. So only three feet of unshielded phone line to the modem, which squirted static chrge over the lamp springs then out the window to the aluminum siding which led the charge 18' to the electric meter - pole drop lines.


The US Robotics 56k Modem won't recognize a dial tone anymore (and I hope the serial port is still alive) but that's not the only casualty from this incident - I added a $30 'Intermatic" whole house surge protector back in 1998 that puts MOV's across primary breaker box inputs - It had two LED's showing and now has one glowing bright & one glowing dim :)


So I'm posting this off the missus's PC - learn what you want from this post, I'm off to lectric store to get a new whole house protector :)

« Last Edit: April 19, 2005, 05:11:32 PM by (unknown) »

nothing to lose

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Re: ever seen Saint Elmo's Fire?
« Reply #1 on: April 19, 2005, 11:28:44 AM »
Glad the UPS saved your system. Hope your serial port is ok too.

My mothers power pole took a direct hit a few years ago in a nasty storm. Knocked out the transfomer and fried her internal modem. It's also good to use the phoneline jack on the UPS, she didn't either. Her whole system was fine other than the modem would not break the dial tone. I think the system was off when the strike occured.

 When we got power back later (days) I had the speaker on, could hear the dial tone and it would dial the numbers, but the dial tone never went away. It was a dell or gateway system, and they replaced the modem free under warauntee. She was lucky that's the only thing in the entire house that was damaged.

Got to watch those phone lines! I was suprised it did not get the TV/vcr or other items like that.
« Last Edit: April 19, 2005, 11:28:44 AM by nothing to lose »

DanG

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Re: ever seen Saint Elmo's Fire?
« Reply #2 on: April 19, 2005, 04:46:38 PM »
Since this was first house built when a farm was subdivided it turns out to be the only house on this entire four-mile-long avenue that gets its power company drop-lines from the other side of a four lane boulevard, actually fed from the streetlight circut, so we are 200+ feet from a dinky transformer.


The phone lines are 150 feet behind the house so the disconnect boxes are at opposite ends of the house - I've kept them seperate so not running lines through the UPS isolator was intentional, though they share earth grounds. The rationle being I'd rather buy phones and modems then computers, TVs and Stereos AND phones and modems if the phone lines got hit. Looks like compartmentalization worked :)


My best guess is a across-the-street grid static sharge was searching for the shortest path to the behind-the-house grid which went through my front porch to the next door neighbors house (12 feet between foundations) then skimmed through their drop lines to the grid in the back alley. Maybe it wouldn't have matered where the modular patch cord was terminated since the potential was pushed through the insulation nearest the lamp, where the cord turned downwards toward the floor.


Serial port is okay, but modem is toast :)

« Last Edit: April 19, 2005, 04:46:38 PM by DanG »

Big All

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Sorry 'bout the modem
« Reply #3 on: April 19, 2005, 11:46:14 PM »
Kinda lucky that's all that suffered.

Gotta be glad is wasn't your magic blue smoke that escaped.
« Last Edit: April 19, 2005, 11:46:14 PM by Big All »

DanG

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Re: Sorry 'bout the modem
« Reply #4 on: April 20, 2005, 06:39:22 AM »
Thanks for reading all that peoples :)


Desk is against front wall of house on ground floor, with window to 3-season porch offset a tad to the right of monitor - The lamp base is less then a metre from my mouse, which I had in my little swaety hand at the time. I was a very up-close and personal thing, seriously - still a little shakey 24 hours later, freaking fish in the aquarium behind me just pushed a 3" tube-house against glass with a clunk and I was  1/2 outta my chair...


Just before the soft click (logic frying in the modem) there was a puff of warm breeeze from over-my-shoulder... maybe they was recharging my blue-smoke, eh?

« Last Edit: April 20, 2005, 06:39:22 AM by DanG »