[sailingdog]

A better option for protecting small electronics is your pressure cooker. It forms a well-sealed faraday cage, thanks to the pressure gasket seal. A refrigerator, depending on what it is made of, may not be a good faraday cage. A microwave oven is probably less protective than a pressure cooker, since they're not solid metal all the way around.

 

[sailingdog]

It won't help at all....if you get hit...the induced voltages won't care if the equipment is running or off... Most unhardened ICs require an an induced voltage of less than five volts to fry them in many cases...and with a lightning bolt's potential voltage and hundreds of thousands of amps...to drive it, that's relatively easy to achieve.

I always turn off my main battery switches. Any comments if this provides any slight protection for electronics, or am I wasting my time.

 

[sailingdog]

The reason lightning does so much damage is that it creates a very high voltage differential as it passes through the boat. That creates a voltage differential across various electronic components internally, regardless of whether the equipment is plugged in, live, or disconnected. That is what does in most of the electronics.

IIRC, the reason disconnecting the COAX from the VHF is that reduces the length of the potential inductor, making the equipment less likely to get fried.

The reason putting electronics into the pressure cooker works is that the solid metal barrier of the pot and lid-which are in solid contact with each other if the pressure cooker has the gasket in and is locked closed-forms a faraday cage that the inductive forces are shunted around-protecting the pressure cooker's contents. This is very similar to the protective effect that most cars offer in a thunderstorm-since most cars form a fairly solid metal cage around their passengers.

Thanks Sailing dog I wont worry in future. I thought the large gap formed when the main battery switches are off may have been enough to encourage the high voltage to seek an alternative path rather than go via my expensive electronics at least with a nearby rather than direct hit. Hopefully Inside an aluminium boat the electronics receive a little protection from the induced voltage if a strike travels via the hull.
At least your advice saves me getting up in the night to turn off the battery switches.

 

[sailingdog]

Microwaves and lightning are two different beasties...and I'd rather rely on a solid stainless steel pressure cooker than a microwave oven.

Of course, I don't have a microwave oven on my boat, and wouldn't if you paid me...just take the money and use it for something more useful for a sailboat, rather than a floating condo. :laugher

Of course the chamber of a microwave is DESIGNED to contain microwaves, so why do you think it wouldn't keep out electrical charges?

 

[sailingdog]

Cam's right-lightning often does some very strange stuff... and it has trouble figuring out what we want it to do...after all, it only lives for all of a couple of milliseconds...and isn't all that smart, regardless of how bright it may appear to be.

There was a girl in NH that was recently hit by lightning and the thing that probably saved her life was a nose ring piercing. LINK You can't make this stuff up...

The statement is wrong only in the fact that given an unimpeded path to ground (which helps), lightning will often choose an impeded path to ground! You just can't trust it to stay on the road you give it.

 

[sailingdog]

All that means is that both you and RV boy are both nuts...

Hey Cammy,
I made this point in a previous thread and the Dog told me I was nuts.
There Dog, Cam does it too.

 

[sailingdog]

Actually, there is also lightning bonding...where you tie the major metal components of the boat together electrically to help them form a "faraday cage" of sorts for the occupants. In theory, connecting the shrouds, stays, bow pushpit, stern pushpit, stanchions, mast, and chainplates together should create a protective "cage" for the occupants of the boat. Generally not done on most boats though.