[AMRadio] Comment on lightning surges

[John Flood]

one of the better surge systems I saw had gass tube for high energy and transorb 
/ MOV for lower energy also including an inductor.  The idea was that the coil 
slowed down the surge briefly to allow the slower gas tube to turn on and shunt 
the high energy to ground with the Transorb / mov's would disapate the 
remainder.  sized correctly(depending on if they were for data line or power 
line) they worked well  Of course the good ground connection is a must for that 
type of system to work

John Flood
KB1FQG

----- Original Message ----
> From: CL in NC <mjcal77 at yahoo.com>
> To: amradio at mailman.qth.net
> Sent: Fri, July 29, 2011 1:58:57 PM
> Subject: [AMRadio] Comment on lightning surges
> 
> At a facility I worked at years ago, all the control lines coming into the 
>building came through lightning protection circuits, mostly consisting of 
>Tranzorbs and discharge tubes  A lot of the control lines were several miles 
>long.  If a storm was in the area, but not necessarily the immediate area, you 
>could turn out the lights at the protection panels and watch the discharge tubes 
>fire as lightning induced spikes from miles away were trying to get in.  Our 
>home installed ground systems at best can handle all the induced stuff, but the 
>major near strikes and direct strike will only be dissipated reliably with a 
>ground system beyond most of out incomes.  Thompson lightning cable, Cadwelded 
>connections, 500MCM cable around the building, and enough ground rods to get the 
>earth resistance the lowest possible might be beyond the wallets of most folks. 
>
> 
> Even with all of that installed, in one storm where the building received a 
>direct strike, I was in the perfect spot to  observe and arc occur on a cable 
>ladder between the edges of the joints.  The ladder was connected to the next 
>section with a plate on each edge, 8 bolts on each side, and also had a 
>continuous #4 ground in the ladder bonded ever few feet.  With all that, it 
>still arced between the edges of two sections of ladder next to the plates that 
>bonded them together.  There was no damage to anything in the building, so I 
>guess the $250K ground system did it's job.
> 
> Charlie, W4MEC in NC
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