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#28848 - 09/01/03 08:26 PM Lighting rods
Heatwave Offline
Member

Registered: 01/05/03
Posts: 11
Loc: Maryland
Any of you guys ever install lighting rods on homes? We have had a few tall beach homes struck by lighting and some customers want to know if rods would be a good safeguard. I have no experience with them. Thanks for all replies.

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#28849 - 09/01/03 08:36 PM Re: Lighting rods
George Corron Offline
Member

Registered: 05/16/01
Posts: 728
Loc: Lorton, Va USA
Heatwave,
Check out NFPA 780, and yes, rods would help. You have to be certified by UL to do so, ain't something you just do, it does take a bit of study.

That said, how struck? I mean a direct strike tends not to leave much behind...... like I always said "Lightning don't strike twice in the same place, cause the same place ain't there the second time".

If they are receiving lots of damage, a ground ring would be your best bet, and then if you want to tie your rod system to it, they could. Put rods on each corner of the home and for gosh sakes, use Cadwelds.

Surge protectors on the service and all incoming conductors such as wells is also advisable, probably too late for the Ufer ground.

If they have a boat house, check the ground for current, I've seen several installations that the boat house was better grounded than the house, and that caused a good bit of trouble all by itself, you have to insure that the main service is better grounded than any subsequent building or structure fed from that source, or you will suffer damage.

Details man, details.......

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#28850 - 09/01/03 08:50 PM Re: Lighting rods
Heatwave Offline
Member

Registered: 01/05/03
Posts: 11
Loc: Maryland
Thanks for the reply. I just completed a trim out on a canalfront home that is 35 feet tall surrounded by mostly ranch style single story homes. This home was hit on the aluminum fascia and traveled down into the vinyl soffit. It looked as something hit the siding with a sledgehammer with no burn marks and left a couple of small burn mars in the soffit below the fascia. There was one kitchen gfi recep taht was fried, one plantshelf recep taht was fried, masterbed arc fault breaker wont reset, and the refrigerator wont operate. About half the sp breakers were tripped. I have not gotten into the troubleshooting of this home yet. The other home was hit the night before this one, I did not wire that one, it did mostly burn to the ground.

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#28851 - 09/01/03 11:36 PM Re: Lighting rods
Big Jim Offline
Member

Registered: 07/18/03
Posts: 377
Loc: Denver, CO USA
Yo might be suprised at how many times lightning can strike. Several years ago, we sold our old church building to a school and had to remove the large Steel cross from the roof. It was readily apparent where lightning had struck it several times. This thing was made out of 10 inch or so square tube so it survived but there were numerous round spots where the paint had been vaporized.

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#28852 - 09/02/03 05:00 AM Re: Lighting rods
George Corron Offline
Member

Registered: 05/16/01
Posts: 728
Loc: Lorton, Va USA
Jim,
Agreed, most folks do not know what to look for. We placed shiny bright copper in a trench one afternoon at an airport. The next morning it was discolored as if it had lain in the soil for years, yup, we'd had a thunderstorm that night, no one else even picked up on it, one of the electricians even complained that he did not understand why it was necessary. I tried to explain the heat it took to discolor the new conductor that way, not sure he believed me.

The signs of surge are often subtle and difficult to see. By not bonding correctly, or carefully considering our surge suppression system, we open ourselves up to shortened life of equipment, equipment that suddenly mysteriously does not work anymore and a lot of little items most never see.

However, even your 10" tube would not have survived the direct strike, but the evidence you present indicates a near strike with large surge. At a prison I worked at, the towers were the tallest thing around for a long ways, never a strike, but lots of evidence such as you state. Most don't understand that lightning rods are NOT meant to take a strike, but to equalize the charge in the air so no imbalance leading to sudden discharge does not occur. Lightning rarely strikes grounded objects.

[This message has been edited by George Corron (edited 09-02-2003).]

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#28853 - 09/02/03 10:53 AM Re: Lighting rods
Ron Offline
Member

Registered: 03/13/02
Posts: 577
Loc: White Plains, NY
_________________________
Ron

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#28854 - 09/02/03 12:29 PM Re: Lighting rods
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
Ron — Your link offers proof of a long-term effort by UL. They finally figured out how to list humans. [Can you imagine their joy?]

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#28855 - 09/02/03 03:07 PM Re: Lighting rods
LK Offline

Member

Registered: 01/21/03
Posts: 1721
Loc: New Jersey
One of our customers just showed us an estimate for a 2800sq ft home lighting protection. $9500 I think we are in the wrong business.

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#28856 - 09/02/03 03:42 PM Re: Lighting rods
LK Offline

Member

Registered: 01/21/03
Posts: 1721
Loc: New Jersey
One of our customers just showed us an estimate for a 2800sq ft home lighting protection. $9500 I think we are in the wrong business. The home next door had this company do an installation, They let us in to take a look, and it was intresting to see
all the work involved to do it right. The cable looked like something you would use to tow a fright train, and the connectors were unique. They said they got a UL certificate
for the installation. I learned something new
that day.

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#28857 - 09/02/03 08:20 PM Re: Lighting rods
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
The lightning-protection biz seems like a “brotherhood” of sorts. it’s one of those “everyone knows everyone else” situations. The “list” of participants is in the introduction of NFPA Standard 780. [I’ve learned just enough to be dangerous—before retirement I was able to attend a ‘facilities’ 3-day course at Lightning Technologies in Pittsfield, MA. It was riveting, but did not qualify me to so much as screw down an air terminal.] It seems that all building installations are carefully engineered before an installer begins work—sort of on a par with fire-protection sprinklers. Petrochems and recreational companies like Disney Corporation spend millions in their construction budgets for protection of users and facilities from lightning.

On the conductor, see http://www.tlpinc.com/fullcat1/conductors.html or http://www.harger.com/catalog2002/2_1_1.pdf ..note illustrations.. Class I lightning conductors are manufactured using a special rope lay process. This process maximizes the surface area of the conductor while allowing greater installation flexibility.




[This message has been edited by Bjarney (edited 09-02-2003).]

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