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
> ---
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