Lightning Rod Questions

[th3w01f]

We had a very close strike last night. Sounded like a handgun going off, didn't even hear thunder. No issues other than our internet dish might have been damaged.

Given the number of nearby lightning strikes this year, we're thinking about looking into a lightning protection system. Does anyone hear know anything about them or how well they work?

[erock]

Lightning protection systems give a low impedance path to ground to get the energy to ground. Current takes all paths, but the path of the least resistance gets the lion share of the current divider. It you don't have a low impedance path, thing like copper pipe, wiring, brick, wood, and concrete get to pretend to be a conductor (with damage). Properly positioned lightning rods will attract the last leader of the stroke and lower the probability of something else get hit. Design should be in an accordance with NFPA 780.


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[Grant H.]

My parents added lightning rods to their house when I was a kid. I had been sent to my room for some reason, and then lightning hit the house, traveled down the corner flashing in the wall, blowing the drywall paste off, and then popping the hot water heat register cover apart. Me being all of 6-8 or something, I was having none of my room blowing up and went running downstairs, which until I explained why I was no longer in my room, earned me more punishment for not obeying my "time-out".

The contractor added 12" tall aluminum spikes on the high points of the house (top of chimney's, peaks, etc) and then ran a heavy braided aluminum cable down the roof from each one to an 8' ground rod that was driven in about 2' below grade. For asthetics, they then used a mask and sprayed the cable to appropriate colors (roof, trim, and siding where applicable). For my parents house, good sized, they added probably around 12 total rods, cables, and ground rods.

Since that was done, they haven't even had a close strike, even with now 100+ foot tree's on the property. We had lost 2 trees and had the barn hit by lightning before, in the space of about 3 years, and then in the last 25-ish have had no issues at all. The contractor had said it would eliminate lightning strikes for some distance around the house, but it seems to be covering the whole 40 acres very well (house is very centralized on the 40 acres).

[Dave_L]

Castle Rock has had a TON of lightning strikes this summer already. My circuits have been tripped 3 times because of close proximity strikes.

Also, I think I know which one you're talking about. Was it about 7/730ish? I was out for a drive along those back country roads and heard a really loud one.

[68Charger]

As Grant stated, A properly designed lightning rod system will prevent strikes by dissipating a static charge before it builds to the point where lightning strikes... the charge will build up elsewhere.

Also, the ground rods tied together will also minimize the localized "Ground voltage"... for example, a horse can be killed by a lightning strike some distance away, because their legs are far apart, and the voltage potential between each hoof is high enough to cause cardiac arrest.

I may not have had the personal experience Grant described, but I am an Electronics Engineer...

[CO Hugh]

I recall reading a Denver post article, a long time ago about a guy in boulder who designed a system to dissipate the lightening so it would not strike. It looked like a bunch of wires in a sphere, so like a porcupine.

[TFOGGER]

One of my good friends worked for a company called LEC(maybe the one mentioned above) back in the 90's designing dissipation arrays for oil storage facilities. He's a member on this board, but isn't on much...

http://www.lightningprotection.com/

[Irving]

I recall reading a Denver post article, a long time ago about a guy in boulder who designed a system to dissipate the lightening so it would not strike. It looked like a bunch of wires in a sphere, so like a porcupine.

This is the only type I've come across, in Boulder actually. Those balls were accompanied by V shaped spikes about 8" tall every 12" along the parapet walls. I thought it was to keep birds from perching, but the spikes were tied into the lightning balls. It sure made it frustrating to climb around to different sections of roof; must have stabbed myself 50 times. No birds though.

[CO Hugh]

One of my good friends worked for a company called LEC(maybe the one mentioned above) back in the 90's designing dissipation arrays for oil storage facilities. He's a member on this board, but isn't on much...

http://www.lightningprotection.com/

Some of the balls look like the ones in the article.

[def90]

I recall reading a Denver post article, a long time ago about a guy in boulder who designed a system to dissipate the lightening so it would not strike. It looked like a bunch of wires in a sphere, so like a porcupine.

I have worked on several homes that use this system.. Not pretty to look at but supposedly works better than the old rod system.