[ProAudio] AES on the west coast, was Re: Ampex/ProAudio List Dinner

[Bob Katz]

What I should have said is that an actual earth ground (bonding) will 
not protect the Ethernet circuit from lightning protection. But it is of 
course necessary for 60 Hz-style safety.

The key is to put the clamping circuit's reference point as close as 
possible to the actual circuit being protected. The farther away you put 
that "ground strap" the more likely your Ethernet card will go up in 
smoke. Because all that energy from the lightning gets put onto that 
long ethernet cable.


Bob



On 11/5/19 2:59 PM, Bill Whitlock wrote:
> Jim,
>
> I'm sure it was Neil who coined the phrase "sump theory of grounding" 
> to mean that currents, especially noisy ones, flow into soil and 
> simply disappear forever.
>
> Regarding earth grounding of lightning protection, I don't fully 
> understand Code in this regard. Yes, lightning strikes themselves need 
> a path to earth - since the strike is a discharge of huge capacitance 
> between clouds and earth soil. But the most common equipment damage 
> comes from voltages magnetically induced into terrestrial  conductors 
> of all kinds. Direct strikes to premises wiring would be catastrophic. 
> Of course, there is also a sudden drop in electric field in the 
> vicinity and this is a problem for "floating" (un-grounded) objects. 
> Perhaps this is the Code's concern. As mentioned earlier in this 
> thread, it sure would be great if they could explain their reasoning!
>
> I think of the strike itself as the (temporary) primary of a one-turn 
> transformer.  All those metal objects on the ground (or in the air, 
> for that matter) are secondaries. Thousands of volts can be induced 
> into a 20-foot-long conductor, depending on whether or not it's 
> parallel to the bolt. I've read that there are about as many 
> cloud-to-cloud discharges as cloud-to-earth, so any orientation is 
> vulnerable.
>
> Bill Whitlock
>
>
> -----Original Message-----
> From: Jim Brown <jim at audiosystemsgroup.com>
> To: proaudio <proaudio at bach.pgm.com>
> Sent: Tue, Nov 5, 2019 11:32 am
> Subject: Re: [ProAudio] AES on the west coast, was Re: Ampex/ProAudio 
> List Dinner
>
> On 11/5/2019 10:07 AM, Bob Katz wrote:
> > An actual earth ground is unnecessary and frankly, useless.
>
> Not true, Bob. Indeed, it is a critical component of lightning
> protection, which is why it is required by electrical codes.
-- 

If you want good sound on your album, come to Bob Katz 407-831-0233 
DIGITAL DOMAIN MASTERING STUDIO Author: *Mastering Audio* Digital Domain 
Website <https://www.digido.com/> No trees were killed in the sending of 
this message. However a large number of electrons were terribly 
inconvenienced.

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