I think Frank is right, when lightening can jump from a cloud to earth there
is not much you can do except have things disconnected. Also it is
possible that the glass jar or some type of insolater may keep sparks,
static electricity from the end of a feed line stop a fire if in dry leafs
or such. I know at times when I unhook my ladder line and there is a storm
in the area I get the electric fence treatment. ED K7UC
-----Original Message-----
From: Jim Shaffer
Sent: Thursday, June 25, 2015 9:38 PM
To: [log in to unmask]
Subject: Re: Lightning strikes, was: Grounding Question
I'm sure Frank that you're right that a direct lightning strike wouldn't be
contained by something such as a glass jar or conventional insulator.
However, if given a choice between trying to stop a bullet with a pillow or
nothing at all, I'd still take the pillow.
--
Jim, ke5al
-----Original Message-----
From: Frank Ventura
Sent: Thursday, June 25, 2015 8:54 PM
To: [log in to unmask]
Subject: Re: Lightning strikes, was: Grounding Question
Hi Mike, I have always been taught that the tops of clouds are the positive=
charges and the bottoms of the clouds are the negative charges and that is=
what the lightning arc is (the negative charges). That theory seems to be =
supported by this article:
http://www.physicsclassroom.com/class/estatics/Lesson-4/Lightning
Frank
-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]] =
On Behalf Of Mike Keithley
Sent: Thursday, June 25, 2015 9:40 PM
To: [log in to unmask]
Subject: Re: Lightning strikes, was: Grounding Question
I think the earth is negative and the clouds ares positive. So we have a po=
sitive to negative current flow.
----- Original Message -----
From: Frank Ventura <[log in to unmask]>
To: [log in to unmask]
Date: Thursday, June 25, 2015 6:27 pm
Subject: Lightning strikes, was: RE: Grounding Question
>
>
> Are you kidding me? Lets think a minute about what lightning is. It is a=
n =3D
> electrical arc, in this case between a cloud and the ground. The arc is n=
eg=3D
> atively charged particles looking for a positive ground, as opposites att=
ra=3D
> ct. Some lightning strikes contain as much as one billion volts (remember=
t=3D
> he first Back to the Future movie?). If that awesome charge is strong eno=
ug=3D
> h to arc several miles through open air can you imagine how easily it can=
a=3D
> rc through a rubber or glass insulator. It is amazing how many people bel=
ie=3D
> ve that the rubber tires of a car keep it from being hit by lightning. Th=
er=3D
> e are two basic reasons why cars don't get hit by lightning with the latt=
er=3D
> being more important, they are:
> a. Cars are relatively low to the ground and are rarely in a position to =
be=3D
> the path of least resistance.
> b. Almost all cars have negative ground electrical systems. Remember from=
a=3D
> bove that lightning is a negatively charge partical arc looking for a *po=
si=3D
> tive* ground to strike. A negatively charged arc is not attracted to a ne=
ga=3D
> tive ground. Rubber tires have nothing to do with it. With all that volta=
ge=3D
> if lightning did hit the car body it would arc the gap from the body to =
gr=3D
> ound below and probably turn the tires into a molten blob of fake rubber =
in=3D
> the process. It is the negative ground electrical system that makes the =
ch=3D
> arges repell not attract. Now with that said there are a few (mostly Brit=
is=3D
> h) cars from the period following WWII that actually have positive ground=
e=3D
> lectrical systems. Electrically speaking they could attract a negatively =
ch=3D
> arged arc but I doubt it has happened much due to the reason given in a a=
bo=3D
> ve.
> So in short if you merely disconnect the coax from the connector on your =
ho=3D
> use and leave it a few inches or even a few feet away from your house you=
c=3D
> an seal it in glass, wrap it in rubber or shove it in a ham sandwhich for=
t=3D
> hat matter and lightning can still arc from the cable to your humble abod=
e.=3D
> =3D20
> Frank
> PS see:
> http://www.google.com/imgres?imgurl=3D3Dhttp://images.nationalgeographic.=
com/=3D
> wpf/media-live/photos/000/002/cache/lightning-over-water_270_600x450.jpg&=
im=3D
> grefurl=3D3Dhttp://environment.nationalgeographic.com/environment/natural=
-dis=3D
> asters/lightning-profile/&h=3D3D450&w=3D3D600&tbnid=3D3DzOwdXoP47bq-8M:&z=
oom=3D3D1&=3D
> tbnh=3D3D160&tbnw=3D3D213&usg=3D3D__zkPY7nzoAY6ktc1km2namr1l0No=3D3D&doci=
d=3D3D21jTPm=3D
> qZw7qgRM
>=20
>=20
> -----Original Message-----
> From: For blind ham radio operators [mailto:[log in to unmask]
] =3D
> On Behalf Of Tom Behler
> Sent: Thursday, June 25, 2015 8:52 PM
> To: [log in to unmask]
> Subject: Re: Grounding Question
>=20
> Jim:
>=20
> Here's an idea:
>=20
> To insulate the coax connector, would it be sufficient to put one of thos=
e =3D
> rubber boots around the connector, such as those that you get with new ru=
ns=3D
> of coax?
>=20
> I would think that should be a pretty good insulator.
>=20
> Tom Behler: KB8TYJ
>=20
>=20
> -----Original Message-----
> From: For blind ham radio operators [mailto:[log in to unmask]
]
> On Behalf Of Jim Shaffer
> Sent: Thursday, June 25, 2015 6:55 PM
> To: [log in to unmask]
> Subject: Re: Grounding Question
>=20
> Tom I never meant to imply that the virtual ground you have would protect=
y=3D
> ou from lightning. Unplugging the antenna is the best way to go as far a=
s =3D
> I know. In fact, it's almost certainly true that if the antenna, or part=
o=3D
> f it, is grounded, that would actually increase your chances of a lightni=
ng=3D
> strike. You should disconnect the antenna, and perhaps put the end of t=
he=3D
> coax in a glass jar, or some sort of insulator. That's of course no gua=
ra=3D
> ntee, but it might keep a lightning strike on the antenna from starting a=
f=3D
> ire in your trailor.
> --
> Jim, ke5al
> -----Original Message-----
> From: Tom Behler
> Sent: Thursday, June 25, 2015 11:32 AM
> To: [log in to unmask]
> Subject: Re: Grounding Question
>=20
> Well, Jim, this is what I'm confused about, and I sure wish I knew what w=
ou=3D
> ld be best.
>=20
> Of course, I guess putting in a ground rod would not hurt anything, but I=
d=3D
> on't think I'm going to be able to do that at least for the next few days=
.
>=20
> For the past several years, I have used the system I described, with no p=
ro=3D
> blems.
>=20
> But, of course, that doesn't guarantee that I won't have any problems in=
t=3D
> he future should the lightning god strike.
>=20
> It's just a difficult call, in my opinion.
>=20
> Tom Behler: KB8TYJ
>=20
>=20
> -----Original Message-----
> From: For blind ham radio operators [mailto:[log in to unmask]
]
> On Behalf Of Jim Shaffer
> Sent: Thursday, June 25, 2015 12:01 PM
> To: [log in to unmask]
> Subject: Re: Grounding Question
>=20
> Tom, from what I've read, what seems important is to be grounded to what'=
s =3D
> around you. It sounds like what you have now is a virtual ground, which =
is=3D
> supposedly just fine. I'll bet, if you do put down an 8 foot ground rod=
, =3D
> you'll see no difference.
> --
> Jim, ke5al
> -----Original Message-----
> From: Tom Behler
> Sent: Thursday, June 25, 2015 9:01 AM
> To: [log in to unmask]
> Subject: Grounding Question
>=20
> Hello, all.
>=20
>=20
>=20
> I know I'll get varying opinions on this, but I have a question about sta=
ti=3D
> on grounding out at the RV camp site.
>=20
>=20
>=20
> As many of you know, my main rig out there is my TS480, and I will be usi=
ng=3D
> my trusty Alpha Delta DXCC multi-band dipole. When all is said and done=
, =3D
> I'm hoping the antenna will be up about 30 feet in the trees.
>=20
>=20
>=20
> Just as I did in previous years, I will have a ground connection running =
fr=3D
> om the ground screw on the TS480 to a terminal ground connection on the b=
ac=3D
> k bumper of the RV. I use 10-gauge wire for this connection.
>=20
>=20
>=20
>=20
>=20
> Of course, I am very careful about disconnecting my antenna at any sign o=
f =3D
> thunderstorms.
>=20
>=20
>=20
> Is this adequate, or should I be pursuing something additional?
>=20
>=20
>=20
> I wouldn't think a dipole would have to be grounded with a ground rod suc=
h =3D
> as is the case with a vertical, or a beam antenna on a tower, but my theo=
re=3D
> tical knowledge in this area is a bit lacking.
>=20
>=20
>=20
> Thanks for any thoughts.
>=20
>=20
>=20
> Tom Behler: KB8TYJ
>=20
>=20
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus=3D20
>=20
>=20
> ---
> This email has been checked for viruses by Avast antivirus software.
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