Power outlet on air planes and ground wire ?

Did you read the news reports? She was not in the air but in her bathtub, presumably taking a bath and possibly talking on the phone while it was charging, when she was electrocuted. There was no airplane involved.

Perhaps ;)

But I still wonder about my question ?

Anybody with a bath tub in a plane ? ;)

Maybe she lived on a plane and called it her home :)

Bye, Skybuck :)

Get back on the meds sunshine !!

I was wondering. Since the earth is flying through a vacuum, and maybe has houses with ground wires, what happens to the ground wire?

Does the earth have a ground? Since it is surrounded by a medium with no ground? HUH ?!

I guess I can just stop wiring my house so that the electrical potential of the ground wire in the outlet matches the electrical potential of my floor and any surrounding metal objects, thereby vastly reducing the chances that I'll get electrocuted, because it isn't "really" ground.

Questions asked from ignorance are not stupid.

Questions asked from an inability to think through the issues are not stupid.

Questions asked by smart people who have all the information available to them but are too damned lazy to figure out the answer -- those are stupid.

He read the news report. He asked questions about it here. They were answered, and in my opinion many of the answers were reasonable, informative, and thought provoking.

But apparently he just wants to be stroked:

I wonder what is the overall voltage of Planet Earth with respect to the universe. I think I read somewhere that it was small.

Doesn't suprise me with all the free energy nut jobs tapping into it.

-Tom

"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...

I think it's only a few million volts, due to static charge rubbed off by solar wind (i.e., the difference in mass between electrons and protons causes an imbalance in ionization). If it were any more, the ~MeV charged particles wouldn't be able to approach, hence the limit.

IIRC, the capacitance of the Earth is 0.7uF or something like that, which suggests a paltry charge of a coulomb or so. The ionosphere to the surface is a much more substantial 45mF, and carries much more charge.

The Sun might be more, but probably not by very much (it doesn't make many GeV level particles, and I can't think of any other physical phenomenon that could cause excess charge), which is pretty impressive given its size: the average electric field is quite small indeed.

Considering the material falling into a black hole is pretty well neutral for the above reason, it stands to reason that a black hole would also be fairly neutral; then again, the accretion process could be launching more electrons than protons off those polar jets, so the voltage it could achieve could be much greater.

Since the Coulomb force has the same form as the gravitational force, it should be possible to calculate when a super-charged black hole starts radiating its own charge away faster than it could be introduced (analogous to Hawking radiation, where gravity pulls apart space, allowing particles to radiate), putting an absolute limit on electric field in the vacuum, and on what voltage an event horizon can have. (The singularity itself will be a singularity in both gravitational and electric fields, but who cares about anything past the event horizon?)

Tim

A Saudi prince wanted to install a swimming pool into his private A380, but Airbus refused, but why ?

There are of course various center of gravity issues, as well as issues with take-off and landing, But would it be much different than with a KC-135 Stratoanker filled with water or DC-10/MD-11 used to combat forest fires ?

All my cell phone chargers have been two wire. No ground required. Case closed.

BTW, I'm kind of doubtful on the Apple story. I mean the charger might say Apple on the outside, but who knows what was really inside. There have been some interesting tear downs of wall wart chargers post on this group from time to time.

The prince would not be happy with partition walls in his pool.

Sigh. I college, my introduction to fluid dynamics, center of gravity, roll center, and inertial forces was when I was talked into flooding the back of my service truck with water in order to make a swimming pool. I don't have a photo handy, but it was an International 1210 4x4 with service boxes in back (6200 lb gvw). The bed footprint was 4x8ft and could be flooded to a depth of about 2ft. At 62.4 lbs per cubic foot, 64 cubic feet of water weighs about 4,000 lbs. Maximum safe load for the truck was 1,500 lbs.

Everything looked fine until I began to move the truck. The first indication of trouble was when I tried to turn a corner and nearly rolled the truck. The truck bed was about 4ft off the ground, resulting in a rather high roll center. The lack of slosh plates in the bed resulted in a swaying motion similar to a drunk elephant walk. Applying the brakes required my doing pull-ups on the streering wheel in order to stop. I eventually arrived at the designated carnival location, where my pickup truck mounted swimming pool was a big hit (it was a hot day). When tear down arrived, some idiot just opened the tailgate, dumping 480 gallons of water onto the dirt lot, creating a muddy mess. Upon returning home, I found that I had blown all 4 shock absorbers.

I can only assume that without proper engineering, reinforcements, slosh plates, and weights and balances calculations, this thing will never fly.

The earth is supported by a semicircular metal frame by two conductive screws located at the poles. The base is grounded to the table, which in turn is eventually grounded to ummm... the ground. Something like this: Incidentally, pressure from the mounting screws are what causes the earth to be slightly flatter at the poles.

However, based on the intelligence of the question and questioner, there is a possibility that he may believe that the earth is flat. In that case, the earth is carried on the back of either a turtle or elephant.

There are also believers in a hollow earth, which suggests that the real ground is actually a capacitor.

The Earth is imbedded in a conductive medium, namely the solar wind. Therefore its net charge is theoretically zero, ignoring plasma effects, which can be strong locally but are negligible globally.

Cheers

Phil Hobbs

Both were put out of work by Usenet trolls. ;-)

It's a turtle.

"See the Turtle of enormous girth! On his shell he holds the earth. His thought is slow but always kind He holds us all within his mind On his back all vows are made, He sees the truth but mayn?t aid. He loves the land and loves the sea, And even loves a child like me."

SK The Dark Tower.

"ground" is just a convenient term to describe the potential of the surroundings. Essentially, it's the potential you might easily come in contact with while accidentally being also in contact with some other potential.

In an aircraft, the obvious ground is the hull.

Sylvia.

A more descriptive name is "Equipotential bonding".

This might have been the situation, but what about the new "plastic" planes from Airbus and Boeing ?

The interesting situation is that when a lightning hits, say, the left wing and exits through the right wing, huge currents (>10 kA) will flow through the plane. With aluminum planes, the current will flow on the outside, generating a Faraday cage. Still the resistance and particularly inductance will cause voltage drop across the path.

What happens if an electronic device is connected to the inside of the left wide (i.e. inside the Faraday cage) to an other one inside the right wing ? If these devices are joined by say a serial cable still inside the Faraday cage, what is the voltage difference between the serial cable ends ?

Of course, in the beginning of the lightning pulse, the current is flowing just at the outside surface of the plane, due to skin effect and hence the inside equipment in the two wings should be in equal potential. However, at the end of the pulse, the skin effect is weakening and the current penetrates deeper and deeper into the aluminum, causing a potential difference between the two devices in the two wings.

For composite planes, special means are needed to achieve sufficient conductivity.

Anyway, since there are going to be potential differences between different places of the hull, does equipotential bonding make sense or just join the electric system at _exactly_ one place to the hull ? If local equipotential bonding is required for safety reasons, then all communication and power distribution to the devices should be galvanically isolated.

It seems that putting more metal wires and grids back into the structure are the favored solutions.

Lightning strike protection strategies for composite aircraft More detail:

However, I notice that carbon fiber / aluminum laminates are not on the shopping list. Maybe the next generation of aircraft.