Re: Lightning surges Dale Farmer <Dale@cybercom.net> wrote: >But when the surge from the lightning bolt reaches the drip loop at the house, >the curves and loops would 'confuse' it. ( hand waving a lot of science I never > >really understood anyway. ) and it would keep going in a straight line and blast > >into the side of the house, where the anchor bolt was attached to the structure >of the house. That loop forms an inductor, so it has a high impedance at high frequencies. Remember we're talking about stuff in the MHz range here. So the air has a lower impedance than the cable does and the current goes through the air instead. This is why we put a loop at the bottom of the antenna cables, to make the impedance to a pulse going into the receiver much higher and encourage the current to take another path. > What these protection devices do is protect your stuff from the lightning >strike that hits a little bit further away. You are at the mercy of the power >companies routing scheme there. And they are not going to change it for >your convenience. To really protect yourself the best, go to a building that >is in close enough to the city where all the utilities are buried. That doesn't guarantee anything, since lightning strikes to the ground can still induce big ground currents as well as inducing trash in buried conduit lines. It reduces the chances, but it doesn't eliminate it. The good news is that your panel actually acts as a surge suppressor; anything over around 6 KV will arc directly across the panel. So when we build surge suppression into power supplies, we don't really have to worry about anything over 6 KV. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis."