Protecting a pelican case from lightning

[Cadence]

Originally Posted by Group9

I had a friend killed in high school who about to get into a car with three other people already inside, when he or the car was hit by lightning. He died, no one in the car was injured at all.

Unfortunately he provided the ground.

[col50]

Originally Posted by GordMay

Most aircraft lightning events occur when the aircraft itself triggers the lightning, when flying through a heavily charged (ionized) region of a cloud. In these instances, the lightning flash originates at the airplane, and extends away in opposite directions.

If an aircraft flies into a cloud, that is about to emit a lightning strike to another cloud, or to ground, the extra conductivity of the plane, and maybe its initial charge, or maybe it's slightly ionized chem-trails can (all) trigger a cloud to plane, or cloud to cloud, or cloud to ground bolt, that just happens to intersect the plane. This is less common, because pilots avoid thunderclouds.

Right on the money, Gord.

[Lasivian]

Originally Posted by dougweibel

The plastic pelican case itself is not an attractive path component.

This right here. Heavy plastic is not going to have much to worry about from lightning.

[Paul L]

Originally Posted by Lasivian

This right here. Heavy plastic is not going to have much to worry about from lightning.

The plastic might not have anything to worry about, but the electronics inside the case sure do. The EMP is what kills electronics and why you want them in a Farafay cage.

[thunderhoof]

Let's not wander too far off the issue of lightning protection on sailboats. Several books have been written about lightning strikes and aircraft.

Everything on Earth is a target for lightning including people, structures, sailboats and powerboats. To protect these items and their contents it is important to provide the most direct path from sky to Earth, and to reduce the impact on sensitive items like people and electronics
The sailboat's mast, even if Carbon, is probably the lowest impedance path from sky to water. The trick is to launch the strike current into and out of the mast with minimum temperature rise (heat damage). In aircraft practice copper mesh is used at probable strike points. Since no-one wants to do this a second approach is to run a sizeable copper wire (#6 or greater) from a metal fitting at the mast top to the keel. The rigging is a poor second choice. Steel rigging, anodized fittings and termination at the deck all add resistance to the lightning path to Earth. The better job you do of steering a lightning strike into the water the more likely your other electronics will be protected. I would still put my cellphones, handheld radios and portable GPS in the oven or microwave. And please, hunker down out of the weather, no standing on deck holding onto the rigging.

[Group9]

Originally Posted by Cadence

Unfortunately he provided the ground.

Yep. I worked for a power line company (as a groundsman) one summer a couple of years after that.

And, one thing that was drilled into us, was to never do anything around the power lines to ground ourselves or the linemen we were working with.

I also learned that pretty much everything conducts electricity if there is enough voltage.

[paul2884]

Steel box, ( needs to shield from the magnetic effects) not earthed, you don't want to make it just another conductor, the type of foam inside wont make much difference as if you have a potential in side the box your Faraday cage has not worked and thee type of foam is pritty irrelevant, anti static foam has a high resistance but then the applied voltage is over 1000000v that might as well be a short circuit! Take paper charts they work so long as you don't have a fire!

[Paul L]

Originally Posted by paul2884

Steel box, ( needs to shield from the magnetic effects) not earthed, you don't want to make it just another conductor, the type of foam inside wont make much difference as if you have a potential in side the box your Faraday cage has not worked and thee type of foam is pritty irrelevant, anti static foam has a high resistance but then the applied voltage is over 1000000v that might as well be a short circuit! Take paper charts they work so long as you don't have a fire!

The box, aka Faraday cage, needs to be made of a conductive material, Steel is not required. The cage can be grounded.

[Adelie]

Originally Posted by Cadence

I don't think you will have a Faraday's cage without a ground.

Doesn't need a ground, just need to be a tight seal all around, with the items inside contained in a non-conductive layer.
Pack the items in Ziplocs then wrap with aluminum foil.

[Ballsnall]

Originally Posted by Cadence

I believe you would be better off with a metal grounded case and the GPS raped in a good dielectric.

Good lord no, don't rape the GPS!

[Cyrus Safdari]

deleted

[Cyrus Safdari]

Originally Posted by jack4566

Paranoid sailor here trying to ensure plenty of redundant GPS systems.

I am going to put a handheld GPS in a pelican case with sealed bags to separate the primary.

You can very easily make a Faraday cage of any metal container like a lunch box or metal ammo container, where the lid makes good contact with the body, and line the inside with something nonconductive

This MAY help protect electronics from the electromagnetic waves that accompany nearby strikes

You can ground it meaning attach it by a wire to a grounding point that carries charge to the sea but strictly speaking this is not necessary
You can buy soft-sided luggage and bags on Amazon that also provide some protection

[Cyrus Safdari]

Originally Posted by Gaia

Why OEMs do not do so is a mystery to me.

Jim sv Gaia

Yhey do on ocean going ships where all electronics are in metal cases that are meant to protect from EMP accompanying lightning

[goboatingnow]

Originally Posted by paul2884

Steel box, ( needs to shield from the magnetic effects) not earthed, you don't want to make it just another conductor, the type of foam inside wont make much difference as if you have a potential in side the box your Faraday cage has not worked and thee type of foam is pritty irrelevant, anti static foam has a high resistance but then the applied voltage is over 1000000v that might as well be a short circuit! Take paper charts they work so long as you don't have a fire!

With 11 devices on board I think I’m happy without paper charts ! ( even though I have a few)

In my three strike strike all handheld devices survived.

[Cyrus Safdari]

Originally Posted by hzcruiser

One could argue the other way around: without a path to ground the lightning would not have struck the chassis in the first place.

Electricity tries all paths first before the shortest path
You can't attract lightning by having a path to ground nor because the mast is metal etc