Crazy Question ... (Lightning)

[markh1f]

The discharge or static electricity to the surrounding atmosphere by use of a wire mast broom, is questionable at best.

Despite this opinion I believe this kind of dissipater will reduce the odds of being hit by lightning and would suggest it is worth a look not because it is an old wife's tale but because it was recommended to me by an electrical engineer that designs nuclear power plants for a living. He also built the control center for Ontario Hydo's power grid and used this technology to successfully protect the control center from lightning strikes over a good number of years when most of their other facilities are hit by lightning multiple times a year.

Mark

[Hamin' X]

Rich do you use the brooms on towers??? I have never seen or installed those on towers... My understanding and maybe memory.... is the broom allows for the build-up, to release ( discharge so to speak) its release capability is enhanced , as the vessel ( that's building up the charge) moves through the ions/atmosphere.......( ? )

Yes, I use dissipators on my communication towers.

Being a ham radio operator and technical advisor (fancy name for the guy who fixes things) for several amateur radio repeater installations, I must operate on a limited budget, so I make my own from SS cable. I have also, worked on commercial communications projects that have almost unlimited budgets. The commercial guys go for the high priced ground systems, including chemical grounds, to control and channel the current. I use the KISS principle and avoid the problem.

Here is a brief description of their use on aircraft:

The static charges that build up on an aircraft during flight tend to accumulate near sharp edges like the trailing edges of wings and tail surfaces. The purpose of static wicks is to provide a conductive path for these excess electrons to flow or "leak" from the aircraft back into the atmosphere. This transfer of electrons reduces the charge on the plane's skin and structure.

The wicks are composed of hundreds of individual carbon fibers wrapped into a cylinder around three to eight inches (7.6 to 20.3 cm) long and about the diameter of a soda straw. Each fiber ends in a sharp point to create a strong gradient in the local electrical field. This gradient attracts the static charge and encourages the electrons to flow off the aircraft and back into the atmosphere. Instead of an ionized corona building up on vital communication antennas, the electrical charges find these wicks more attractive.

Static discharge wicks also provide other important safety benefits. In the event of a lightning strike, a plane is designed to conduct the excess electricity through its skin and structure to the wicks to be safely discharged back into the atmosphere. Though this massive electrical charge often burns or melts the wicks, these devices are simple and easy to replace. Wicks are also relatively fragile and easy to damage, so pilots and ground crew routinely inspect them in case replacement is needed. Because of their importance, regulatory agencies like the Federal Aviation Administration (FAA) require static wicks aboard all civil aircraft. Static Discharge Wicks

The secret is to have many sharp points. This is why lightning rods have single sharp points, to concentrate the charge build up, so that it reaches the level of a single discharge that attracts the lightning strike where you want it. The dissipators have many discharge points that allow for the discharge to occur, without reaching the critical threshold. For the same reason, car and other antennas have small balls, or other rounded shapes on the tip. This discourages the built up static from concentrating on the tip and creating disrupting static in the receiver.

Despite someone's statement that lightning is not static electricity, it is. The charge in the clouds is built up as a static charge, as is the charge from the earth. When the charge on either side is lessened, so is the chance of discharge.

~Rich

[Divecoz]

Gentlemen use what you like .....
BTW A Chemical Ground is nothing but a copper pipe filled with "salt... per say" though "Maybe" special salt and used in rocky and sandy areas.
As for Static brooms used for lightening arrest on Micro Wave Towers , or The Sears Tower, or anywhere I have worked in 37 years.... let alone Concrete Buildings or Nuclear Reactor Domes (or anywhere on a Nuc for that matter) ....New's to me ... Hanford 2 & 4 Seabrook 1& 2
Smoke em if ya got em...Gentlemen

[Rick Westlake]

Yes, I use dissipators on my communication towers.

... I make my own from SS cable. I use the KISS principle and avoid the (lightning-channeling) problem.

The secret is to have many sharp points. The dissipators have many discharge points that allow for the discharge to occur, without reaching the critical threshold.... The charge in the clouds is built up as a static charge, as is the charge from the earth. When the charge on either side is lessened, so is the chance of discharge.

~Rich

Rich, is that one of your homebuilt "wire broom" dissipators? I'd like details on how you make them.

There's a lot of uncertainly about lightning, its propagation and behavior ... and how to defend ourselves from it. Seems to me that we can either provide a big fat conduit to carry the lightning "away to a safe place", or make our boats less attractive to lightning by lowering our static potential. (Aw, heck, you said the same three years ago in the "Lightning strike scare" thread.)

"Make myself less attractive to lightning" was the original purpose of lightning rods, and the reason they were sharp-pointed ... their inventor had experimented with "Leyden jar" capacitors, and observed that a jar with a pointed electrode out the top leaked-off its electrical potential into the atmosphere. And he'd observed, with a kite and a key, that the electrical potential of a thunderstorm is the same as the static electricity "natural philosophers" were starting to explore. Was "Poor Richard" justified? History says yes.

Does the "broom" dissipator reduce our chances of a lightning strike? Seems so. Does it eliminate the potential? You, being a ham radio operator, know more than I do about that - but I've seen enough broom dissipators in use that I'm encouraged to buy, or build, one for Bossa Nova.

Do you use one on your masthead?

Thanks -
Rick

[Divecoz]

as discussed why not just add a cheap car antenna to the mast. Make it a side mount and you'll have all the static discharge capability a car has. Remember the old static strap? But what about GM vehicles they mount the antenna in the rear glass ....... how are they discharging static?

[Hamin' X]

No, the picture is of a commercial product available from Tessco.

First, let me say that I am not an expert, just someone who works with very sensitive electronics, in high lightning environments. Run anything that I say through your BS filter and study it.

I make my own from scrap stainless steel aircraft cable and scrap stainless steel tubing. I cut a 6" length of cable and about 1 1/2" of tubing. Diameter is not critical, but the cable must be a snug fit into the tubing. I flatten one end of the tubing and depending on how it is going to be mounted, may drill an appropriate sized hole through the flat part. I use a die-crimp tool to secure the cable into the tubing, then fray out the strands. Sorry that I don't have any pictures handy, I am on the road and will not be at a tower site to take any for at least two months.

My method allows the positive charge that is accumulating on your structure to dissipate in it's low current stage, before it can create an ionized path for a high current discharge of lightning. If you use the bond and ground method, you are creating a lightning rod and if you do not have everything bonded together and have an adequate ground, you are just asking for trouble.

Is anything a sure cure for lightning? Nope, not even the big boys can control it all the time. If you use a dissipator system and you are the only thing around and the lightning decides that you are the best path, you're going to take a hit. One of my mountain top repeaters is used by the National Weather Service as part of their Skywarn system. It takes a lickin' and keeps on tickin'. The big boys around me use grounding systems and take all the hits.

As far a some folks saying that I'm all wet when it comes to what I say, Look at the high voltage transmission lines. There are three voltage carrying lines and then the ground line. The ground line runs above the transmission lines and is called a guard wire. It's purpose is to attract the lightning and divert it to ground. Got it? It is grounded and attracts lightning.

~Rich

[Kelly Hanson East]

Lightning is static electricity, but it is a very dynamic process and not to be confused with the static you get in your couch/rug in the living room..this is basically redistribution of separated charges.

For instance, even though most strikes look like they go air-to-ground, the visible part of most strokes originates mid air and goes up, then fills in the rest of the 'apparent path' in most strikes.

[Rick Westlake]

Just picked up "Why Didn't I Think Of That?" - a compendium of hints and tips for cruisers - and found two pages on lightning protection, headed with this "general tip":

Plan on being struck by lightning. Among the 120 cruisers we interviewed, 16 had been struck by lightning at least once on their present or an earlier boat. We have been struck twice on Sea Sparrow. Two other boats -- Dolly and Sea Fever -- each reported damage from direct or indirect lightning strikes on three different occasions.

Ugh. That's a better than one-in-eight chance ... too big to "ostrich away"....

Since I'm planning to spend multi-day voyages gunkholing on the Chesapeake Bay and other thunderstorm-prone areas, that StrikeShield system is looking more and more attractive.

[Divecoz]

No, the picture is of a commercial product available from Tessco.

First, let me say that I am not an expert, just someone who works with very sensitive electronics, in high lightning environments. Run anything that I say through your BS filter and study it.
~Rich

If your directing any of this at me YOU! Need to check your own filter dude..

[dvideohd]

Lightening is regional as well.... Most strike probability is in Florida...

Lightening can travel up - or down - or both...

Sometimes small... sometimes large... a good conductive path can help channel the small stuff to gnd.... Might keep the big stuff from deciding YOU are good path to flow through...

Golfers have a high mortality versus sailors... on a per hour basis, I wonder which is more dangerous..

Rich has the right of it......

--jr

[Hamin' X]

Don't be so touchy, Dive. I was replying to a question from Rick Westlake. The BS filter comment was a caution for each individual to do their own research and not just take my views, nor anyone's views as gospel. The stakes are too high. I offer my opinion and point in a certain direction, nothing more. My opinion may be worth exactly what I charge for them.

~Rich

No, the picture is of a commercial product available from Tessco.

First, let me say that I am not an expert, just someone who works with very sensitive electronics, in high lightning environments. Run anything that I say through your BS filter and study it.
~Rich

If your directing any of this at me YOU! Need to check your own filter dude..

[craiglaforce]

Its simple, just wear a full metal suit of armor with an ion dissipator broom on top of the helmet.

[David Mellon]

Like This?

[Hamin' X]

Gotta love Marvin.

~Rich

[craiglaforce]

Yes Indeed. We have much to learn from Martians and Marvins. I think he is also the driver on "Top Gear". Looks taller on-screen.