> Lightning is the same for commercial, non-commercial and
> part-15...it doesn't care. Don't cheap out. polyphaser.com
>
>
> If you want to find out your chance of getting hit, I use
> this formula:
>
> S = F(contour) * 0.375 * h2 * 10-6
>
> S = strikes per annum
> F(contour) = mean annual number of days with thunderstorms
> h = height of tower in feet
>
> For example, central PA is 35 on the lightning contour and
> our towers are 79 meters...soooo...
>
> 35 * 0.375 * 262.52 * 10-6 * 2 = 1.81
>
> (multiplied by 2 because of 2 towers)
>
> So my site sees an average of just under 2 strikes per
> year...which is pretty accurate. We're always getting hit.
>
> Found the formula in a white paper from Nautel.
>
Hi,
The problem with these kinds of predictive estimates is that you do not know when, and even if you did, what would you do differently? Sam wrote "So my site sees an average of just under 2 strikes per year...which is pretty accurate. We're always getting hit." Just wondering if always getting hit = twice a year?
Plan for the worst. So back on topic, I hope, use single point grounding and comply with local electrical codes as a start. If you have a typical part 15 AM intstallation with an outdoor antenna and the transmitter at the antenna, there is no way to protect this from damage from a direct or nearby strike. What you want to do is keep the lightning out of your house. The power and audio grounds in the cables need to be grounded at the point of entry. Other lines can be protected with spark gap suppressors. Check out Universal Amateur Radio or similar vendors for products you might use.
There is a good thread about this on this board in the engineering section. As a start, you should read this.
http://www.radio-info.com/mods/board?Post=606603&Board=engineering
Hope this helps.
Neil
