On Sun, 30 Nov 2003 22:26:31 -0500, "Alex Batson"
wrote:

Consider:

The National Electric Code says otherwise. Earth ground is *not*
considered adequate bonding for the purposes of electrical safety.

The bonding rule is there for a very good reason... safety.


Bonding the grounds together will cost maybe $10 worth of wire. It's
cheap insurance.

My main pannel's nutral bar is attached to a stranded 2AWG wire attached to
the cold water pipe (from 1963). Other work done in 2001 by a contractor
has a solid 6AWG wire on the nutral bar, going out to a stake in the back
yard. He tied the gas line in the house, to the cold water pipe, and also,
in another area of the basement, tied the copper sewer line to the cold
water line. Am I good-as-gold with this setup?

Here the answer would be no, but YMMV depending on location (local
codes)

Although tied together the Neutral and ground are not considered the
same. Neutral is the return to the power transformer on the pole and
is normally the same size at the hot wires. (220 VAC). There should
be a ground at the pole and one (or two) within 6 to 12 feet of the
service entrance.

*Here* and I emphasize here, that ground varies with the size of the
service, but for a 200 amp service I believe it was #6. It had to be
"Green" and tie to the ground clamp in the breaker box. In the breaker
box is a jumper that ties the neutral and ground together. My
electrical service for the house has two 8 foot ground rods, one with
in 6 feet of the entrance and the other at 12 feet. The shop with the
same size service (200 amp) only has one ground rod.

BTW, although the ground wire is #6 the feed wires are 2 ought, or
(#00) for both the house and shop. It takes pipe benders to get that
stuff around the bends in the meter sockets and panels. Both the
house and shop are fed with underground runs of about 130 feet. Some
where I have some photos of me running the "trencher" across the
driveway to install the PVC conduit.

The gas line should have another Green wire (insulated except at the
connectors) of the same size tieing back to the ground in the breaker
box. Each of the other lines should also have it's own green wire
going back to the breaker box ground. Only one ground wire from the
box to the ground rod(s). This puts all of those metallic systems
tied to the same potential. We were not allowed to "daisy chain"
grounds. Each had to be a separate run and all tie to the buss where
the green from the ground rods ties in.

Again, I emphasize *here* is quite likely different than *there*
although I'd assume they'd be close. Everyone has to meet the national
electric code, but some areas are more strict. (I make no claim to
being an expert on the national code, but having just rewired our home
including installing a transfer switch to a 9 KW generator I am up on
the local requirements) Part of this is still under way.
Here being, Homer Township, in Midland County, Michigan.

You'll have to fix the return add due to dumb virus checkers, not spam
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair?)
www.rogerhalstead.com

alex
batsonaatcomcastdotnet

Steve,

Sorry, you are the one who is furthering the lightning rod myth. There is no way
a "true lightning rod" bleeds off enough charge to avoid a strike. That idea
is about 99% urban legend.

I suggest perusal of the Polyphaser web site. There is a lot of good information
there. One relevant comment is:

"The real solution for lightning protection is to have control of the strike
energy. To do this, a well-designed ground system will be a better investment
than cluttering up the top of the tower."

The cluttering refers to a bottlebrush arrangement of multiple sharp points, but
the same idea applies to a single sharp point.

As usual, Mark is right on target.

73,
Gene, W4SZ

Steve Nosko wrote:
Though in practice you are correct to express concern, your reason is
not properly stated. You further the lighting rod myth.

Actually, "if the antenna acts as a lightning rod." He'll have little
problem. The purpose of a true lightning rod is to blead off the charge,
defeating a strike, not to attract it. A lightning srtike will blow any
lightning rod system to smithereenes.
When a charged object has a sharp corner or point, the charge tends to
collect there. Because there is more charge at that p[oint it will have a
higher concentration and therefore a higher voltage. It builds to the point
of forming a corona/plasma and will discharge it. That's why the van De
Graf (sp) generators have the round ball on the top. They WANT to build up
the charge and not loose any more than necessary..
I all fairness, I do not know if lightning rod systems work in
practice.They do wear out due to the discharge corona and should be
sharpened periodically. Apparently the points of the typical beam are
not sufficient or they wouldn't get struck, no?

73, Steve K,9.D;C;I


"Mark Keith" wrote in message

In my case, those are pretty much the same place. All my grounds tend
to rise in potential at the same time, being they are all tied
together at the base of the mast. Nothing is perfect of course, but
you sure don't want any large potential differences between grounds.

It's not just a simple CD circuit.
I've seen tower strikes where there was such a strong current and fast
rise time, the magnetic field quenched the current flow and the
lightening got off part way down and jumped sideways to something
else.

If I remember right, the original poster was going to mount an antenna
on a roof. That has the potential for even more serious problems if
the antenna acts as a lightning rod. He'd want as few turns or sharp
bends in the ground wire to earth. This is why I much prefer using a
metal mast on the side of the house to support verticals or other high
risk antennas, rather than a mast attached to the roof of the house.
And then hoping a ground wire will safely direct the charge to
earth...It usually will, at least much better than the house itself,
but it's kind of scary if it has turns or bends.
The important part at the house is making sure that everything rises
together so there's no lower resistance path for the charge to take
through the shack or house. At the mast, I always tape all coaxes or
wires to the mast, and run them all the way down to earth to try to
avoid flashing problems. So far in two strikes to the mast, I haven't
noticed any, and I have a breaker box, elevated power lead in, phone
lines, cable lines, all within 5 ft of that mast. MK

On Wed, 03 Dec 2003 19:56:06 GMT, Gene Fuller
wrote:

Steve,

Sorry, you are the one who is furthering the lightning rod myth. There is no way
a "true lightning rod" bleeds off enough charge to avoid a strike. That idea
is about 99% urban legend.

I suggest perusal of the Polyphaser web site. There is a lot of good information
there. One relevant comment is:

"The real solution for lightning protection is to have control of the strike
energy. To do this, a well-designed ground system will be a better investment
than cluttering up the top of the tower."


I'd be a bit careful about that statement on a site for a company who
makes their money from attempting to control the energy when
lightening strikes, rather than preventing the strike. There are two
distinct camps. The one that says the solution is to control the
strike and the other says to prevent the strike. Lightening strikes
are unpredictable in most cases, but if you have the tallest structure
around the odds are that it will get hit before lower nearby
structures.

The cluttering refers to a bottlebrush arrangement of multiple sharp points, but
the same idea applies to a single sharp point.

According to our electrical inspector it's not a myth, but I don't
know one way or another. However I do know that it would take little
to bleed a charge and a lot to control a strike. I also know that
every tall structure at the chemical company where I used to work had
lightening rods

Bleeding supposedly does just that. I prevents the charge from
building up to a potential that will help bridge the gap to the
feeders. The last class I had at work on electrical safety was pro
lightening rods AND ground systems. (as was the one for skywarn from
the NWS)

I do use polyphasers and end up replacing one every now and then. My
tower gets hit on average of three times per year. Since the tower
went up there have been no strikes to any home within about 5 lots
from me.

There haven't been any really close strikes that didn't hit the tower.
(of which I am aware). The neighbors are quick to tell me, "Man you
shouldda been home this afternoon when the lightening hit your tower".
That happened in August this year. They were really impressed and
more so in that we had no damage even to the radios which do not get
disconnected.

My antenna ground system has over 600 feet of bare #2 copper wire with
30 grounding rods, not counting the two ground rods for the house
electrical system and the one for the shop. They have separate feeds,
but as my computer network ties it all together, I'm thinking of
bonding the grounds for both services together and to the system
ground. I have visions of a lightening strike to one system and
reaching ground in the other by going through the 130 feet of cat-5
cable. There's a reason I back up everything on CDs and DVDs.

You'll have to fix the return add due to dumb virus checkers, not spam
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair?)
www.rogerhalstead.com

snip

Roger Halstead wrote:


The cluttering refers to a bottlebrush arrangement of multiple sharp points, but
the same idea applies to a single sharp point.

According to our electrical inspector it's not a myth, but I don't
know one way or another. However I do know that it would take little
to bleed a charge and a lot to control a strike. I also know that
every tall structure at the chemical company where I used to work had
lightening rods

Bleeding supposedly does just that. I prevents the charge from
building up to a potential that will help bridge the gap to the
feeders.

I don't know if I would call it a total myth, but I call it fairly risky
none the less. I know I sure wouldn't trust one to protect me from a
strike. I don't think they can bleed the charges from constant hard wind
and rain fast enough to do any good. It's like taking a whiz in a
whirlwind.

The last class I had at work on electrical safety was pro
lightening rods AND ground systems. (as was the one for skywarn from
the NWS)

I agree there, if he is talking about the traditional pointy lightning
rod used to protect other gear or buildings. I'm of the opinion strikes
can never be totally avoided, and the brush things are a waste of time.
I've heard of many reports of them being struck. Sometimes spraying hot
metal around and causing a fire hazard. And you still should have a good
ground even with those. To me, the only sure thing is expecting the
strike to happen, and safely controlling it's path to ground when it
finally does. So I'm firmly with polyphaser on that one. MK
--
http://web.wt.net/~nm5k

There is a short video available (saw in a search of lightning arrestor
systems) that shows the Empire State Bldg being struck several times, and
not once does the lightning "visibly" hit, follow, or otherwise act
impressed with the elaborate grounding system on the building. Taken as a
whole though, it must be effective, because the strikes do no apparent
damage, and they obviously get to the ground somehow.

JP

"Mark Keith" wrote
The last class I had at work on electrical safety was pro
lightening rods AND ground systems. (as was the one for skywarn from
the NWS)

I agree there, if he is talking about the traditional pointy lightning
rod used to protect other gear or buildings. I'm of the opinion strikes
can never be totally avoided, and the brush things are a waste of time.
I've heard of many reports of them being struck. Sometimes spraying hot
metal around and causing a fire hazard. And you still should have a good
ground even with those. To me, the only sure thing is expecting the
strike to happen, and safely controlling it's path to ground when it
finally does. So I'm firmly with polyphaser on that one. MK

Jack Painter wrote:
"Taken as a whole, though, it must be effective, because the strikes do
no apparent damage, and they obviously get to ground somehow."

True. I`m skeptical of claims of lightning avoidance by discharging the
earth beneath the thunder cloud. I think the protection is from
substituting a more attractive target to the lightning than the one you
want to protect.

I`ve worked with too many radio towers. Many had inverted Copperweld
ground rods bolted to the tower tops with the pointed end aimed up.
Function of the rods was protection of beacons and other appurtenances
atop the tower.

The towers still get lightning strikes but the beacons don`t get damaged
from the tower hits when there`s a Copperweld lightning rod up there.
I`ve seen broken and burnt beacons from towers that didn`t have the
rods.

A radio tower with a sharp-pointed lightning rod is very salient and
should discharge the earth under and around the tower, if this is a
prctical course. From what I`ve seen these lightning rods do not prevent
lightning strikes but they do prevent some of the damage that lightning
causes.

Best regards, Richard Harrison, KB5WZI