Lightning & Telephones

[cisco]

After a lightening strike took out a bunch of appliances and the phone, I "saw the light" and placed surge protectors (the good ones) on my incoming phone line, cable TV line, electric meter (fits just under the meter) and, just to be sure, an in line unit just before my TV / stereo system, and my computer. Too many hard luck stories in my area re. damage from lightening strikes to risk it anymore. Just when I was feeling smug, and safe, lightening zapped one of the houses in our area and started a fire. So, I placed an array of 6 short lightening rods, and two runs of 3/4" copper cable to large rods buried in the ground.
There's something I haven't thought of, no doubt, so when and if I get smoked by lightening, I'll let you folks know how it got me.
And yes, the protection I placed is somewhat costly, and a hassle to do, but --- a TV, stereo, computer and all those appliances aren't exactly free either -- and a "happy" wife having to do without them until you buy new ones - well, that costs too (more grey hair, for you).

 

[ByronBob]

They sell now the 6 strip plug adaptors now with the GFI in them with a phone GFI which you plug the chord from the wall into the GFI and the GFI to the modem. Somebody listened to us after all. /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

 

[techman]

One fact that everyone here should realize, protection devices, such as surge protectors and plug-in "lightning arresters" are only capable of dissipating or bypassing relatively low energy discharges. These are the result of lightning near-hits, where a high voltage is induced into wiring (outside) that is in the proximity of the strike. Voltages induced may reach the hundreds or even a couple of thousand volts, and the surpressors will help protect sensitive equipment.

When lightning takes a direct hit on your wiring or structure, and device in the path will be fried, surpressor or not. I have seen quite a few surpressors blown apart, melted or burned from these occurances.

Similarly, telephone safety is a function of how close the hit is. A nearby hit, which induces voltages in the lines may result in a "shock" feeling from a phone handset. A more direct hit will cause more severe damage and/or injury from a phone (like the melted phone example), but you are just as likely to be injured by such a strike from proximity to any number of electrical appliances, or even the house's plumbing. It is a bit of acrap shoot that there is a direct hit, and you are near something that is somehow connected to the wiring.

I have no hesitation about using the phone during a storm, since the chance that everything goes in a way that I get zapped is quite small.

paul

 

[Gomez]

I will not use the phone nor take a shower during a lightning storm.

I know it's something my parents used to always tell me not to do, but it turns out they weren't so dumb after all. One thing I remember growing up is going around and unplugging everything during a storm. Still probably the surest insurance. /forums/images/graemlins/smirk.gif

As others have said, surge suppressors will help, but will not guarantee protection from line surges.

 

[chim]

There was a story on the news a couple years ago about a woman getting struck (she survived) while chatting on a cell phone in a storm. She was at a baseball game, and the story claimed that the cell attracted the lightning.

Our company has done some projects that required lightning protection systems. The work had to be performed by licensed subcontractors. We had some interesting discussions with them. At least one (Heary Brothers in NY) has a system that uses a device with a small radioactive source that is able to cover a large area without the usual large number of rods (or as they call them, " air terminals").

Their website is listed below.............chim

http://hearybros.com/english/index2.html

 

[AggieDave77]

Here's the link from Snopes.com
lightning and telephones
In a nutshell, is it possible?....Landlines - yes; Cell/Cordless phones - No

 

[dbelisle]

One of the most important things you can due to try and keep lighting out of your house is to make sure your electrical service is properly grounded and the phone system is grounded to it. One of the main reasons for a good service ground is to try and keep lighting out of the house.

There is a little yellow tag on the phone companies ground wire where they connect to the ground . It warns you about making sure this wire is connected .

Lightning is going to take the path of least resistance.

Most of the time I find lightning has taken out phones and appliances because the grounding isn't correct.

The utilities in this area require two ground rods to be installed as well as grounding to the water service. If it is a well system and plastic pipe is used we run a #4 copper wire to the well casing and ground to that. All grounds need to come back to the same point on the electrical service.

The other very , and I mean very important thing to remember, is to ground all your services like phone and cable TV back the the same grounding point on the electrical system service.

If you have differant grounds on a building, you could have a lighting strike come in one ground and go right through your building's electrical system to get to the other gorund.

Dave in NH

 

[techman]

Well stated dbelisle.

One other point that requires some additional focus - the well casing. For many years, and still today many installers do not ground the well casing. The thinking is that it "is" grounded. Grounding it has an additional valuable purpose.

When lightning strikes a tree, or other object in the vicinity of a house, the resultant current travels through the earth, which is not a particularly good conductor. A well casing offers a better ground, due to the large area of the casing pipe in contact with earth (like a hugh ground rod), and the current from the strike will follow the classic "path of least resistance" to the well casing. What happens next is the problem.

The electrical grid, ground and power conductors, are a much better "ground" , or low impedance return path, to the lightning. Even a lower resistance path than the well casing. A nearby strike can flow current into the well casing, and the current often finds the better path by arcing through the submerged pump's motor insulation to flow into the power grid wiring, as a better return path. This is the most commom cause of fried pump motors - not a direct hit to the well or the power lines, but a ground or tree strike within a few hundred or thousand feet of a well.

By grounding the well casing to the house power ground, it helps to prevent any voltage difference between the casing and the grid ground. This removes any voltage potential that would arc through the pump motor's insulation, as well as providing an enhanced ground for your home.

I live in a fairly densely wooded area and often have thunderstorms in the area. We have never had any strikes closer than many hundreds of feet away, but the trees often take a direct or secondary hit (yes we are also on top of a large hill). I lost 2 pump motors in 5 years due to nearby lightning hits. I grounded my casing to the house (on advise of an old timer who made me aware of the potential causes mentioned above) and I have not had a failure in the 13 years since.

paul

 

[Gomez]

I have worked on several substation projects for my company over the last few years. We have two kinds of lightning prevention systems in addition to the standard lightning protection system required by code.
The first is the isotope based system you mention, another one we recently installed had five towers with a "dandelion" made from an array of stainless-steel rods bent at varying angles. lightning eliminators

Supposedly, you can see an ion stream coming off the electrodes during a strong storm.

The substation's been in operation since 2003, so far so good. /forums/images/graemlins/grin.gif

 

[techman]

Much of lightning protection is to prevent a strike, rather than absorb a hit. The devices you mention are basically the equivalent of dozens of small lightning rods. Like a lightning rod, it is intended to reduce the likelyhood of a strike. It works by lowering the voltage gradient (potential) in the air when a storm is there. For lightning to strike, a potential of hundreds of volts per meter height must exist. This is why people report feeling the charge, or having their hair stand up right before a close strike. A grounded, pointed electrode will drain away the voltage potential and create a sort-of ground bubble around the electrode, removing the voltage gradient needed to support a strike at that area. The two drain (ground) wires that run along the top of top of high tension towers does the same thing, draining voltage around the tower, and creating an umbrella zone around the towers and wires. That's why those towers are rarely struck. It's all about draining the charge in the air.

paul