VK5TM wrote:
Unfortunately, there are many sides to and debates about lightning protection, so there is a lot of bulldust mixed in with good stuff.
Yes, that's true and you can see some of it creeping into this thread.
Lightning arresters will do their job. But they are not a lot different to a fuse.
A fuse will protect part of a circuit in particular circumstances, but not do so in others.
Wearing a seat belt in a car increases your chances of surviving a crash, if does not guarantee your survival.
.... disconnect all cables that could conduct lightning into the shack.
Disconnecting everything is a fairly good way to ensure the best chance of equipment survival.
VK4WTN wrote:.....left his ground buss connected to the radios but the lightening was able to totally destroy all his radios via the ground connection.
The only safe way is to disconnect everything from the radios, antennas power and ground.
regards Wayne VK4WTN
This wins my award for myth of the day. I might suspect that somebody has coloured up this story isn't telling any truth.
Starting with an indication of a poor earthing system. Possibly with an earth loop of some kind.
For "all" of the equipment to be destroyed, also seems very unlikely. Even site where I've seen a direct hit to equipment, the damage is localised and in a lot of cases other equipment in close proximity continues work without an issue. Think of the chassis of a radio as a farraday cage. Either somebody is telling you the laws of physics don't apply to them, or there are some exceptional circumstances they are not telling you about, either deliberately or because they are not aware of them. This often comes in the form of accusations against a deity.
And it's easy to think carefully about if this is true or not by doing a simple thought experiment.
Ask ourselves how to deliberately damage a radio with a lightning strike without connecting anything but an earth wire.
I think you'll find it requires a direct strike to a part of the radio that isn't the chassis and has a different earth at a different potential close by.
"Correct" earthing (not ham radio standards) is a very important part of protecting against lightning damage.
An Earth mat short of a farraday cage offers the best protection.
EQUIPOTENTIAL BONDING. If everything in the shack is at the same potential then no damage will occur.
(In this forum you will obey ohms law.)
In reality it's impossible to have zero ohms to everything inside the equipotential boundary. So again it doesn't prevent against catastrophic conditions but it certainly does offer very good protection.
Depower equipment
Disconnect antennas.
Disconnect external cables like rotator control cables.
Disconnect cables to power supplies like 240V plugs.
Do not disconnect your earth wires. (Unless you have a poor earthing system in which case I wonder why you bother earthing anything in the first place)
Do not leave cables, microphones etc lying in close proximity to earth other.
Of course if your antenna is hit, it's going to come down the coax, jump the insulation to the microphone and find it's way to earth ruining your day in the process.
But, if your tower was earthed, and your radio was bonded to the same earth as the tower, then your radio and the tower will be at the same potential when the strike occurs.
The potential from the coax to the microphone will be minimal and damage will most likely not occur provided there isn't a better earth somewhere else close by.
Which begs the question again. Why is your earth not as good as that one and why didn't you bond to it ?