Interesting. Suppose the service entrance is at one end of the house,
and the ham shack at the other end? I don't think it's physically
possible to provide a low inductance path that's 60 feet long, is it?
Would a solution be to DC-isolate the station from the grounded
antenna?
Say with a wideband toroid 1:1 transformer? Then ground the station
through the
3rd pin of the AC outlet?
Here in the San Francisco Bay Area, lighting is rare. It used to be
entirely
unheard of - we just don't get the kind of convective weather that
produces it. We're more about coastal stratus. But with climate change,
that might be changing. There was quite a display once last year.
- Jerry, KF6VB
On 2023-07-31 13:20, Fred Jensen wrote:
Be very careful of advice regarding lightning protection. There are
some very good sources, starting with the NEC and including material
from ARRL. Some is somewhat non-intuitive. For example, the NEC
requires that any additional "earth electrodes" [aka ground rods] be
bonded to the service entrance earth electrode with a low inductance
path. There's been quite an array of advice circulating here recently,
much of it wrong, some dangerous.
73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County
Geoffrey Feldman wrote on 7/28/2023 5:02 PM:
First thing and foremost - switches are mostly not relevant to
protection.
Energy that can travel 1000' through the sky is likely to continue
across
most switches. So, the utmost of safety is what you indicated you
did -
disconnect. By disconnect, I mean either disconnect outside the
building,
leaving the feed on the ground or leave the feed connected to a copper
plate
that is in turn connected to an 8' deep ground stake. On the inside
of the
house, disconnect the lines from that plate and leave them on the
floor.
Another such stake near the feed point of the antenna is also a great
idea.
If it's possible to lower the antenna when not in use, that's a great
idea.
This should be the default when not in use.
You have the belief that no grounding system is perfectly effective
(for all
imaginable strikes) - maybe, but a good grounding system is far better
than
foolishness. A grounding system, or an antenna is not a "lightning
magnet". If it doesn't strike it won't. If it does it will and the
grounding
system assures the energy will be less likely to cause harm. Some
places and
circumstances are more or less likely but everywhere is possible. If
that
possibility happens, a good grounding system is why it is likely to be
survived.
A key thing to understand is that when Lightning strikes in nature,
all the
energy travels along the surface of the ground. It can do this for
many
feet and be lethal doing it. Anything that stands along the radius
from the
point of the strike (one part closer and the other further) is in
danger.
Four legged animals, having more distant contact points, more
dangerous.
The purpose of a ground stake (8' straight down) is to channel the
electricity deep, rather than along the surface.
Don't use emotional theories. Read the lightning mitigation and
grounding
books offered by the ARRL. Use UL approved conductors and stakes. Do
not
use your homes electrical service ground stake. Keep that separate.
All the above is a "cliffs notes" and so is anything else posted
here. Read
the books. Ask senior members of a local club, to review your plan.
W1GCF Geoff
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