+++++++++++++++
Date: Fri, 28 Jun 2002 12:50:04 -0400
From: "Hare,Ed, W1RFI" <w1rfi at arrl.org>
To: Low Power Amateur Radio Discussion <qrp-l at lehigh.edu>
Subject: [128724] RE: Lightning

Info on lightning and the limits of lightning protection:

http://www.arrl.org/tis/info/lightning.html

http://www.arrl.org/tis/info/antgrnd.html

http://www.arrl.org/tis/info/elecsfty.html


73, 
Ed Hare, W1RFI
ARRL Lab
225 Main St
Newington, CT 06111
Tel: 860-594-0318
Internet: w1rfi at arrl.org
Web: http://www.arrl.org/tis


+++++++++++++++
Date: Fri, 28 Jun 2002 11:08:32 -0500
From: "Mark Andrews \(KE4IOF\)" <KE4IOF at ke4iof.com>
To: "Low Power Amateur Radio Discussion" <qrp-l at lehigh.edu>
Subject: [128720] Lightning

In 1997 I developed a whole new respect for lightning. It was during Field
Day and our club had deployed all its gear on the nob of a mountain
overlooking the Tennessee Valley (in Northern Alabama). It was a great site
owned by one of our members.

About 3 in the afternoon, typical summer thunderheads started to build. It
wasn't long before one of these developed into a fast moving thundershower
and was headed for our site. Like idiots, we ignored it.

The rain came, and we ignored it. The wind came and we ignored it. The
thunder boomed and we ignored it.. Then came the lightning. It would not be
ignored.

While it didn't strike me directly, I felt its affects as it traveled from
my computer, down my right arm, side and bare leg through the metal chair I
was sitting in. The chair was situated on bare ground.  We did not ignore it
any longer. The back of my leg had a red spot on it for a few days and my
whole body was sore for about a week.

The humans in the group were lucky. Our equipment didn't fare so well. I
personally lost two radios, a power supply and a TNC. Others in the group
lost equipment as well. The city of Moulton, Alabama lost a brand new 10KW
diesel generator it had loaned us for the weekend.

Do not ever think you are safe from lightning. You do not have to be struck
directly to suffer the consequences. I was lucky.

Five miles of air will not stop lightning. Neither will 3/4" plywood, nor
shingles, nor a $4.95 surge suppressor. It is doubtful that you could
provide a sufficient ground with enough capacity to conduct the current in a
lightning strike in a manner of your choosing. The best thing to do during a
storm is to disconnect everything from the outside world. This means
disconnecting everything in your shack from antennas, phone lines, power
outlet and even your ground connection. After the analysis of our Field Day
strike, we theorized the current didn't propagate through our antenna
systems, but through our power systems.

There is one humorous aspect to my story. The tent I was sitting under was
loaned to us by a funeral home, you know, the kind they put over the grave
during a service... You think maybe they were trying to drum up business?
:-)

Mark, KE4IOF
_________________________________
Mark A. Andrews

++++++++++++++++++
Date: Fri, 28 Jun 2002 12:27:55 -0400
From: "Mike Yetsko" <myetsko at insydesw.com>
To: "Low Power Amateur Radio Discussion" <qrp-l at lehigh.edu>
Subject: [128723] Re: Lightning

If lightning strikes, there's not really a thing you can do, unless you
are
in a faraday cage that is really heavy duty.  I have personally seen the
effects of a strike where it hit the corner of a parking garage, and took
out a ton of computer equipment in the basement.  A ton as in a ton
of scrap metal.  This hit melted right through our copper grounding
grid under the computer room floor.

But, there's a lot you can do to ward off a strike.  And that's where
putting the antenna in the attic can really help.  Here I personally have
80 to 100 foot trees around my house.  To the point my wind gauge
is almost useless, I'm just in too much of a 'well' from the trees.  Even
still, I totally unplug my antenna that is a dipole between the trees
when there's a storm.  But if I had a dipole in the attic, protected from
the static buildup, I'd probably leave it connected if it was IMPORTANT
to do so.  Unless it was life or death, I wouldn't leave my dipole
connected.

Thing is, once that strike takes place, there's very little you can do if
it's
a direct hit.  But, the secondary induced surges you CAN try to limit
any damage.  And you can try to ward off the strike in the first place
with a proper installation.

Mike
>
> > DON'T YOU BELIVE IT ................... !!
> >
> > Do you ACTUALLY think lightning that has travel from a cloud is a
little
> put
> > off by your ROOF ?
> >
> > We had a local whos attic antenna was struck and melted all the solder
in
> > the radio while DESTROYING IT ! Actually and truly, the solder was all
> over
> > the bottom cover. The copper from the coax was all over the basement
> floor.
> > The house caught fire but the fire department saved it. If it is a
DIRECT
> > hit, there is little you can do. Now if it hits the guys house behind
you
> > and all you get are fingers, grounding MAY save you but things are
still
> > passing HUMUNGUS amounts of CURRENT to ground. Had one of those here
years
> > ago, blew a chunk out of the loading capacitor in the old APACHE
> transmitter
> > and killed the blitz bug that was in the coax line. I learned to
disconect
> > both the antenna and power cords from that ! :-(
> >
> > Walt K8CV Royal Oak, MI.
> > ----- Original Message -----
> > From: George, W5YR <w5yr at att.net>
> > To: Low Power Amateur Radio Discussion <qrp-l at Lehigh.EDU>
> > Sent: Thursday, June 27, 2002 12:56 PM
> > Subject: Re: putting an antenna under my siding
> >
> >
> > > Bet it picked up a lot less noise, too!   <:}
> > >
> > > But, I have four full-size dipoles in my attic for 80, 40, 30 and 20
> > > meters, all fed through a 1:1 balun with a single RG-213 coax. True,
> they
> > > are noisy and cause RFI but when it is stormy and all the outside
> antennas
> > > have to be disconnected, they still work "good enough" to keep
things
> > > going.
> > >
> > > In fact, I worked one of the Spartan Sprints using those antennas
and
> did
> > a
> > > respectable job even though it took almost maximum DSP NR in the PRO
to
> > > handle the static and lightning crashes!   <:}
> > >
> > > 73/72/oo, George W5YR - the Yellow Rose of Texas
> > > Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
> > > Amateur Radio W5YR, in the 56th year and it just keeps getting
better!
> > > QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771 I-LINK
11735
> > > Icom IC-756PRO #02121  Kachina 505 DSP  #91900556  Icom IC-765
#02437
> > >
> > >
> > > W2SH at aol.com wrote:
> > > >
> > > > Ever since I tried wire antennas in the five-foot-high crawl space
in
> > this
> > > > ranch house, I've been against the idea of placing antennas in
close
> > > > proximity to the house.  In my case, the difficulty arose from the
> fact
> > that
> > > > all the electrical wiring in the house goes from room to room by
going
> > up to
> > > > the crawl space, across and down to the next room.  I learned that
a
> > dummy
> > > > load worked just as well, and it was far less work.
> > >
>

+++++++++++++++
Date: Fri, 28 Jun 2002 09:58:35 -0700
From: "Tracy Markham" <tracy at bytemark.com>
To: "QRP-L" <qrp-l at lehigh.edu>, <KE4IOF at ke4iof.com>
Subject: [128725] RE: Lightning

Lightening is awesome powerful.

I come from Orlando, the lightening capital of the world. The clouds are
LOW, maybe 300 -500 feet off the ground and they are violent. It is not
uncommon to go 45 minutes without one microsecond of relief from the
thunder. And I mean THUNDER, the stuff that cracks windows.

I took a direct strike to a vertical last summer that reminded me of where I
had lived all my life. It not only blew the fiberglass hamstick to pieces,
with parts over 5 neighbors yards, it ignited the coax like a fuse and
caused quite a lot of smoke and stink in the attic and workshop. The induced
currents from the coax (which was running bundled up with my network wires
...) burned out all my hubs and computers. Three computers literally blew
pieces off the boards and one gave out a belch of smoke that got the fire
department involved.

It was a mess, and an insurance nightmare.

The tower was grounded properly, probably too well. The rig was grounded
well, as well as everything on the bench. All blown to bits. Next time I
think I'll use a cement block and a coke bottle to insulate the push up pole
from ground!! hi

It's random - you can do anything you want to hide from it, but if it hits,
it's going to hurt.
Tracy N4LGH

+++++++++++++++++++
From: "Guy Olinger, K2AV" <k2av at contesting.com>
To: "Elecraft Reflector" <Elecraft at mailman.qth.net>
Subject: Re: [Elecraft] potential of static damage
Date: Fri, 14 Mar 2003 21:43:37 -0500

For those of you worrying about grounding, part of the problem in
understanding what goes on is that the amount of charge delivered by a
lightning strike completely overwhelms the ability of the material in
the "ground" to "absorb" the strike.

For most of our everyday uses, the ground is a huge electron sponge
that behaves as a huge neutral. Not so in a lightning strike.

The capacitor effect formed by a charged cloud overhead can accumulate
the opposite charge over hundreds of acres below. When a strike
occurs, the short circuit to the capacitor occurs JUST AT THE POINT OF
THE STRIKE.

This means that all the charge meant to neutralize acres of opposite
charge is present in a tiny area around the point of the strike while
the opposite charge is still spread over the acres.

The next thing that happens is that the huge charge at the strike, and
the opposite charge all over the acres flow toward each other to
neutralize each other. This can occur with an ionized path in the
ground itself (killer of buried telephone cables) or in a "wave" that
spreads out over all or a large part of the compass.

THAT is when all of the damage occurs that is not precisely at the
point of the strike. This is sometimes called induced, though that is
a bit of a misnomer.

There will be a very large current that will spread out from the
strike point, that does not come to equilibrium until the opposite
charges are satisfied.

This ground charge equalization current is subject to the same ohms
law and impedance issues as any current.

What goes wrong if ALL THE GROUNDS IN AND AROUND THE HOUSE are not
tied together?

Remember that the charge is moving AWAY FROM the strike point to
equalize. The house may have a crawl space or a basement. Either is a
BLOCK to current. The crawl space will be drier than around the house
(or you wish it was) and less conductive. The basement is just an
impassible block.

Grounds on the strike side of the house will charge up to whatever the
ground is as the charge "wave" goes by. If that ground is directly and
heavily connected to a ground on the other side, the charge will use
the ground tie to move through/under/whatever your house to the other
side. If not?

For the period of time that it takes for the charge to move AROUND the
house (not long, really, but long enough), the strike-side GROUND WILL
BE HIGH POTENTIAL to anything connected to a ground on the other side
of the house.

If there is a connection, but it is circuitous, or has an impedance to
it, and cannot carry a large surge current, the effect is reduced but
still present.

If there is not a single point entry and ground for EVERYTHING
conductive, and I mean EVERYTHING, then grounds have to be connected
across. EVERYTHING includes ANY conductor of ANY type leaving the
house, including pipe, tubing, etc, besides RF and electrical
connections.

Failure to do so and you have the likes of one story already posted to
this thread.

This equation can be complicated by parallel conductors buried next to
one another, etc, etc, but the principle remains the same.

My son-in-law mistakenly left the neutral/safety ground leads
ungrounded at an outbuilding that he ran power to. A lightning strike
A QUARTER MILE AWAY in line with the power run put all the conduit in
the building above ground (including the concrete floor), including
the frame of the drill press he was using. He woke up five minutes
later after being thrown 20 feet clear across the room.

I think I was most fortunate not to have a death in the family that
day.

Takes far less than that to smoke a piece of electronic gear.

73 and stay safe,

Guy.

++++++++++++++++++
Date: Tue, 20 May 2003 15:53:19 -0400 (EDT)
From: k4wtf at enterzone.net
To: Vic Rosenthal <vic at rakefet.com>
Cc: Steve Jackson <ssj at nc.rr.com>, elecraft at mailman.qth.net
Subject: Re: [Elecraft] Re: no PolyPhaser?


On Tue, 20 May 2003, Vic Rosenthal wrote:

> Something important to keep in mind (which I'm sure Steve has done but 
> didn't mention) is that in addition to the antenna leads which go 
> through the lightning suppressors at the entrance plate to the house, 
> you should also pass ALL of the AC, telephone, rotor, etc. lines for the 
> shack through the entrance plate with appropriate suppressors.  That way 
> there shouldn't be any large differences in potential between circuits 
> inside the shack if there us a nearby strike.

The house layout dictates that I can't (or it would be VERY hard) to bring
in AC, Telco, CATV, RF and Rotor/Switch cables via a single entry point or
even within several feet of each other so, as it stands, the AC, Telco and
CATV leads come in via one entrance at one side of the basement and the
RF, Rotor/Switch cables come in on the other side about 15ft away.

I have implemented a DITEK "whole house" surge arresting system now.  It
consists of the following:

On the AC power, I have installed the following at the service panel:
Model: DTK-120/240 CM
Connection Method:  Hard wired, parallel 
Response Time:  <5 nSec installed, <1 nSec component level 
Operating Frequency:  0 - 400 Hz 
AC Protection Modes:  L - L, L - G 
Service Voltage:  120/240VAC10 
Max Surge Current:  25,000 Amps per Mode 
Max Energy Dissipation:  420 Joules 
MCOV (L-G):  130VAC 

On the telco circuits, I have installed the following at the DEMARC:
Model: DTK-2LVLP-SCP-RUV
Class:  Low voltage line protection 
Connection Method:  Screw terminals, 22 - 14 awg wire 
Continuous Current:  <150 mAmps 
Response Time:  <5 nSec 
MCOV:  175VDC 
Max Surge Current:  9000A per pair 
Max Energy Dissipation:  76 Joules per pair 
Typical Let Through Voltage:  130VRMS 
Protection Modes:  L-G (All lines protected) 

On the CATV, I have installed the following at the DEMARC:
Model: DTK-VSP-A
Class:  Coaxial Cable Protector 
Installation Point:  CATV Entry 
Connection Method:  Female IN/OUT 
Response Time:  <5nSec  
MCOV:  75VDC (center pin-shield), 38 VDC (shield-ground) 
Impedance:  75 Ohms 
Standing Wave Ratio:  1.2:1 
Band Pass:  0-1.5 GHz 


Does anyone have anything good/bad/indifferent to say about the DITEK
products?



For the RF lines and rotor/switch lines, I am redesigning the system.  The
antennas are down and the gear is either in repair or being prepared to be
sent to repair after the lightning hit.  The hit did NOT come in the RF or
the rotor/switch lines but, this still gives me the opportunity to build a
better grounding/arresting system.

I am looking for a source of copper plate currently.  Something that I can
then mount the polyphasers, knife-switches, ICE equipment to and then
connect to my copper strap that goes to the ground rods.  I know that
polyphaser sells one but,.$70.00 for a piece of copper plate seems to be
a bit extreme.  Surely there is some other source.

Alternately, I suppose that I could use some other metal plate but, my
thinking is that copper will be the best bet.  Does anyone have any
suggestions on sources and comments on copper vs some other metal plate?

Also, I'm getting mixed messages trying to do research on how to properly
set up the ground system.  Some people say DON'T connect it to the
electrical ground, some people say DO connect it to the electrical
ground.  Which is right?

Also, I've been told to keep the ground as short as possible.  Does this
mean the ground strap from my bus point to my ground rods or the
overall length of the grounding system?  I ask this because the run from
the "bus" to my ground rod is about 12ft.  It will be another 25-30ft
from that ground rod to the electrical service entrance if I want to bond
the two.


This page: http://www.k9wk.com/litenin.html has something similar to what
I'm trying to achieve.  He is using the $70.00 polyphaser copper plate
though.

Any ideas, suggestions, etc would be nice.


73, John - K4WTF
...used to have the station pictured at http://www.k4wtf.com/

++++++++++++++++++
From: "Stuart Rohre" <rohre at arlut.utexas.edu>
To: <k4wtf at enterzone.net>, "Vic Rosenthal" <vic at rakefet.com>
Cc: "Steve Jackson" <ssj at nc.rr.com>, <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] Re: bonding of various ground rods
Date: Tue, 20 May 2003 16:43:20 -0500

Lightning mitigation practices change as more research and knowledge is
gained of the medium of damage.

For example, years ago, they said (not so many years ago), to coil up coax
and rotor leads to form a cable choke as it left the tower if above ground
level, so that the lightning would tend to go in a straight line down the
tower leg.  The inductive reactance of the coil would prevent it from
turning the corner and following the coax or cable.

Now they say this could form a one winding transformer and induce high
voltage into the lines worse than if you only made a 90 degree turn with the
coax, etc.

They used to say do not ground to rebar in the tower base.  Now they say to
bond it to the ground rods as well.  Lightning is somewhat inexact Physics
because there are differing types of strokes, and the energy can vary over
very large orders of magnitude.
You may suffer thousands of amps or only hundreds.  A stroke may vaporize
some conductors, or it may only follow along a telephone wire as a bad
surge.

The National Electrical Code calls for all radio, AC, and telephone grounds
to be bonded to each other.  There is a good reason for this.   The copper
paths will have a difference of potential around the house from one ground
rod to another, but this will be far less than the difference of potential
thru the rock and dirt from one ground rod to another, and so all the
grounds should rise to some high voltage together rather than being at
differing potentials thru the earth such that you have surge currents or
differing voltages side flashing from one ground to another.

The best ground we can get here in a rocky, poor conductivity area is to run
a copper conductor circling the house, and bond all the other grounds to it.
It is buried (even in a shallow trench), to give more surface area for
charge dissipation.  The surface area is what you want --for the charge to
spread out.

The crowfoot grounds put on tower legs helps to promote the charge to reach
ground and not go all thru one tower leg, but to divide among the area of
multiple copper conductors into the earth.

You want to follow the National Electrical Code, which has had the bonding
requirement for many years.  That way, your insurance company cannot balk
saying there was an installation deficiency in case of your claim.
72, Stuart K5KVH

++++++++++++++++
Date: Fri, 23 May 2003 14:27:57 -0700
From: Vic Rosenthal <vic at rakefet.com>
Organization: Transparent Software
To: Stuart Rohre <rohre at arlut.utexas.edu>
Cc: k4wtf at enterzone.net, elecraft at mailman.qth.net
Subject: Re: [Elecraft] ?OT? Grounding/Protection question...

Stuart Rohre wrote:
> John, your set up for protection sounds pretty good, but 16 feet between
> ground rods is a half wave at 10m,  and  a quarter wave on 20m, so watch for
> any RF in the shack issues on those bands.  

Lightning grounds are an entirely different animal than RF grounds.  A 
ground rod or group thereof is a very poor RF ground, although 
functional for lightning protection purposes.  Depending on the type of 
antenna, no additional RF ground may be required (dipoles or beams with 
baluns, for example).  Vertical monopoles, of course, do require RF 
ground systems.

It is possible to make a combined RF/lightning ground (e.g., you could 
make several of the buried radials for your vertical out of no. 4 copper 
and string some ground rods along those radials) but in general the 
structures are different.  Even in this special case, the ground rods 
would probably have very little effect on the RF grounding properties of 
the system.

The recommended spacing for ground rods along a lightning protection 
radial is twice the length of the rod, so John seems to be following 
standard procedure here.

73
Vic K2VCO

++++++++++++++++
Date: Fri, 23 May 2003 21:11:05 -0400 (EDT)
From: k4wtf at enterzone.net
To: Vic Rosenthal <vic at rakefet.com>
Cc: Stuart Rohre <rohre at arlut.utexas.edu>, elecraft at mailman.qth.net
Subject: Re: [Elecraft] ?OT? Grounding/Protection question...

On Fri, 23 May 2003, Vic Rosenthal wrote:

> Stuart Rohre wrote:
> > John, your set up for protection sounds pretty good, but 16 feet between

> Lightning grounds are an entirely different animal than RF grounds.  A 
> ground rod or group thereof is a very poor RF ground, although 
> functional for lightning protection purposes.  Depending on the type of 
> antenna, no additional RF ground may be required (dipoles or beams with 
> baluns, for example).  Vertical monopoles, of course, do require RF 
> ground systems.

Unless I'm somehow mistaken, the lightning grounds and RF grounds should
be tied together anyway so, it is all one system.  Some designing a
"Lightning Only" ground system may not have a "Star" or "Multiple
Star" type system that you may see from someone with a couple of ground
mounted verticals but, in both events, the "ground system" is going to be
used to shed energy from a strike.

If I ever get a tower (not for a while, I'm sure, unless the Tower Fairy
visits my QTH), I'll attach a run from the existing ground bus out to the
base of the vertical and then create a "star" of ground radials from the
end of that run.  I'll still put ground rods every 16ft though since from
what I understand, the additional ground rods won't make the RF ground
radials perform any worse (or any better?) but, they will certainly give
the lightning ground system a serious boost in the load shed capacity
area.

> 
> It is possible to make a combined RF/lightning ground (e.g., you could 
> make several of the buried radials for your vertical out of no. 4 copper 
> and string some ground rods along those radials) but in general the 
> structures are different.  Even in this special case, the ground rods 

OK.  Now I'm getting the picture.  I suppose that most "RF grounds" that
people lay to run verticals against aren't constructed out of #4 solid
bare copper.  That explains why they don't do too good when it comes to
shedding a lightning load.

Does anyone know if my "double protection" (polyphaser at the "dog
house" and also at the SPG panel) will double my load shedding
capacity?  I'm not certain.  I don't think that it can hurt anything
though and unless someone tells me it will, it is going to be a bit of a
"security blanket" for me.

73, John - K4WTF

+++++++++++++++