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Climbing an electrical pylon. Will I be protected by the Faraday cage effect?


Neil9327
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As summer is here in the UK, I am considering following in the steps of Benjamin Frankin and Michael Faraday by doing an experiment with electricity. There are lots of 400,000 volt supergrid pylons dotted around the English countryside, so why not climb one?

As I make my ascent, will I not be protected from a spark jumping across by the faraday cage effect?

 

I have not actually decided to do the climb, am only considering the idea at present.

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It may be an unutterably dumb idea, as well as illegal, but I think climbing the tower itself isn't a shock hazard. There's enough distance from the conductors to the tower to make sure ther's no arcover even in high winds and heavy rain.

On a calm, dry day it should be safe. particularly if you climb up the inside of the tower.

Of course, if you try this and get hurt don't blame me. I already said it was dumb.

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It may be an unutterably dumb idea, as well as illegal, but I think climbing the tower itself isn't a shock hazard. There's enough distance from the conductors to the tower to make sure ther's no arcover even in high winds and heavy rain.

On a calm, dry day it should be safe. particularly if you climb up the inside of the tower.

Of course, if you try this and get hurt don't blame me. I already said it was dumb.

 

Finally a relevant answer.

That's what I was thinking - if you are on the inside of the tower then surely if you were close enough to the conductors to get arc-over then the metal of the towers themselves would by definition be even closer so you would already have got arc-over.

 

I suspect in practice that if I was to begin the climb and approached the level of those wires I would probably start to get worried about the possibility and lose my nerve. Especially with that manic buzzing sound you often get with supergrid lines.

 

So I won't try this climb. I'm sure you'll all be glad to know lol.

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Klaynos, I wonder if we are talking at crossed purposes here.

This sort of thing.

http://en.wikipedia.org/wiki/Pylon

looks to me like it would act as a Farady cage for anyone inside it.

It's conductive and it's earthed.

Cages don't need solid sides (Or Mr Faraday's "box" would be beter known).

 

Why don't you think it's a Faraday cage?

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Because a cage is a box (or other shape) of conductor (grids work hence cage) where the charge on the outside exactly cancels on the inside... they in fact are not earthed...

 

So a pylon fails on not being a full enclosure and also by being earthed.

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A bad idea, mostly due to being a falling hazard, as well as illegal. And you would have to stay away from the wires, or you may find that they take a shortcut through you to the metal and down to the ground. This looks more like a dumb idea than an experiment. If you aren't completely sure that it is safe, you shouldn't do it. If you are completely sure it is safe, it is not an experiment.

 

There's lots of cool experiments that don't have the risk of falling to your death, such as turning a lemon into a battery.

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The veiw might be good from up there.

Anyway there doesn't seem to be any requirement for a Faraday cage to be isolated from earth or completely enclosing (hence "cage" rather than "box")

http://en.wikipedia.org/wiki/Faraday_cage

On a practical basis, if I were in the middle of nowhere when a lightling store brewed up I think that sitting on the ground in the middle of a pylon would be a good place to wait out the storm.

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Yes I looked at the photo and I know what a pylon is. But fundamentally it has no base of the cage and is grounded.

 

The reason it has to be not earthed is then the charge wont spread out evenly to remove the field inside, it'll just disappear into earth.

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It's a conductor so the charge will flow through it until it balances the applied field.

The base of the cage is the ground- it's conductive

There's nothing magic about the earth- as an isolated sphere it has a capacitance of something like 1,000µF. If I connect a 10,000µF capacitor to a Faraday cage, does it stop working?

If I hold a charged body near a thin stream of water from the tap the stream is diverted slightly. However it's a good enough conductor that it's still earthed. This doesn't stop the charge diaplacement. You can still have a charge displacement on an object that's grounded.

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The difference is that the charge will NOT be distributed evenly around the edge of a pylon as it will a Faraday cage. If you replace one side of a Faraday cage with a 10,000µF capacitor it will no longer be a Faraday cage.

 

A charged pylon would very quickly go back to being the same charge as the earth (~0) because it is earthed, that isn't how a faraday cage works a faraday cage maintains its charge and spreads it evenly around the surface making the effect from all the charges cancel to be 0 inside the cage.

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"The difference is that the charge will NOT be distributed evenly around the edge of a pylon as it will a Faraday cage."

Faraday cages work because the charges are not distributed evenly. The charges rearrange themselves unevenly so as to cancel out the external field.

 

". If you replace one side of a Faraday cage with a 10,000µF capacitor it will no longer be a Faraday cage."

So what? That's nothing to do with the question I asked.

If I connect an intact faraday cage to a capacitor does it stop working?

If not, why should it stiop working when I connect it to the earth?

 

If I put a piece of metal rod in the ground and hold a charged object near it, say a balloon rubbed on my jumper (and for the sake of illustration, let's say it's positively charged), do you think the rod will stay as it is or do you accept that the charge will attract electrons from the earth into the the rod?

If you think that it will stay neutral would you like to explain how an electrophorus works?

http://en.wikipedia.org/wiki/Electrophorus

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"The difference is that the charge will NOT be distributed evenly around the edge of a pylon as it will a Faraday cage."

Faraday cages work because the charges are not distributed evenly. The charges rearrange themselves unevenly so as to cancel out the external field.

 

OK, that is another effect of the cage, but requires the same physics, and you still need a charge surplus.

 

". If you replace one side of a Faraday cage with a 10,000µF capacitor it will no longer be a Faraday cage."

So what? That's nothing to do with the question I asked.

If I connect an intact faraday cage to a capacitor does it stop working?

 

I honestly don't know, but in the case of the pylon one whole side is replaced, discussing other wise is a strawman.

 

If not, why should it stiop working when I connect it to the earth?

 

You're replacing a whole side. And removing excess charge.

 

If I put a piece of metal rod in the ground and hold a charged object near it, say a balloon rubbed on my jumper (and for the sake of illustration, let's say it's positively charged), do you think the rod will stay as it is or do you accept that the charge will attract electrons from the earth into the the rod?

If you think that it will stay neutral would you like to explain how an electrophorus works?

http://en.wikipedia.org/wiki/Electrophorus

 

Again this situation is not the same as having a charged conductor earthed.

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"You're replacing a whole side. "

No I'm not. I'm replacing metal, which is a conductor with earth which is also a conductor.

Saying I have removed it is the strawman.

 

and I don't see how you can possibly say that this "If I put a piece of metal rod in the ground " is not the same as "having a charged conductor earthed"

 

 

Let me make this as clear as I can.

It is perfectly possible to have a conductor which is connected to earth and which has, at the same time, a net charge on it.

 

So earthing a Faraday cage won't stop it working.

 

(as witnessed by the fact that many if not most of the examples given in the wiki article are earthed).

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Anyway there doesn't seem to be any requirement for a Faraday cage to be isolated from earth or completely enclosing (hence "cage" rather than "box")

 

precisely. the most extreme form of a faraday cage is a hollow metal sphere. obviously in there you're safe. now make lots of really tiny holes, you'll still be safe because it's easier for the electrons to flow around the cage, since the resistance is lower. there would be no effect on the potential difference between two point of the cage.

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  • 2 months later...

Something maybe even more fun than climbing the tower and a lot safer is to get a group of people together under the power line in the dark and tell them you are going to perform magic. You unsheath a flourescent lightbulb, being careful to keep it perpendicular to the direction of the lines, say some mumbo-jumbo, then thrust the lightbulb into the air, turning it paralel to the lines. The tube will glow enough to be seen but not like if it was lit up by a ballast, so you apologize for your power being weak that particular evening and do something else, like dropping mentos into a bottle of diet pepsi.

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Nope you're likely to die... I also believe it's illegal in the UK.
Illegal, as in a punishment is imposed to deter someone from doing something. And the punishment for dieing would be?

 

Also don't hold the tube by it's end, hold it in the middle. You might make yourself a little too tall. Probably NP but just to be safe.

 

I should imagine there being issues with the electric field if you were able to get to close to the power lines even if you maneged not to get electrocuted directly.

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