[Elecraft] A dumb question about lightning

[Fred Jensen]

Not sure you got an answer to your question ... two rules of thumb:

1. Follow the NEC, it's incorporated in building codes, essentially the 
law, and failure to do so could possibly invalidate your insurance claim 
should you need to file for damages.

2.  Read and use the techniques and procedures in the ARRL Grounding and 
Bonding book, don't make up your own.  I think the book is about $30.  
It is well worth the price.

3.  Avoid advice from internet lists ... see #1 and #2 above.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

jerry wrote on 7/31/2023 2:14 PM:
> 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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