The Accidental Smallholder Forum
Community => Coffee Lounge => Topic started by: ZaktheLad on September 20, 2013, 07:46:03 am
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I wondered if anyone could tell me why it is that birds are able to sit on electricity wires and not get electrocuted? If we were to touch these same wires we would be dead instantly. This has always puzzled me ??? ::)
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they don't touch anything else so no circuit is completed so no effect, in theory we can do the same but as we are bigger we tend to touch other things easier and go kaboom!!!
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Its because they are not completing the circuit I think, if we could balance on the wire, far enough away from the ground we would also be ok. But generally when we touch wires we are touching something else too, part of a support, or a ladder, or the earth, and that completes the circuit and Boom.
Just being above the ground and only touching the wire might not be enough tho, as the electric could arc across gaps so it would need to be very well clear up in the air.
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Thanks - that explains it very well :thumbsup:
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They'd need to have one foot on the wire and one foot on the ground - for the 'earth' connection.......could be a bit of a stretch :innocent:
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A stork might manage it :innocent:
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its why swans and geese who fly into overhead pylons can die if the touch 2 wires at the same time KABOOM!!!
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its why swans and geese who fly into overhead pylons can die if the touch 2 wires at the same time KABOOM!!!
how can they get electrocuted if they arent near the ground?
we had a swan here with a broken wing due to flying into the wires.
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touching 2 wires at the same time also completes a circuit trust me s a really bad idea...
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touching 2 wires at the same time also completes a circuit trust me s a really bad idea...
Are you speaking from experience then....?
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i have seen a demonstration shall we say...
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OK then, a bird perches on a wire. You're using electricity in your house. There is therefore a complete circuit, of which the bird is a part. So he'll get a small current up one leg and back down the other then...... which would at least keep his feet warm!? ;D
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:roflanim:
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OK then, a bird perches on a wire. You're using electricity in your house. There is therefore a complete circuit, of which the bird is a part. So he'll get a small current up one leg and back down the other then...... which would at least keep his feet warm!? ;D
That would apply if the bird had legs 100 mtrs apart . the resistance of the wire between it's legs when only 40 mm or so apart will be so low as to be lower than the birds resistance so the eddy current running through the bird will be infinitesimal and not make any difference.
it is interesting to watch birds driven along on wet storm weather hit the pot insulators ... that does sometimes result in a decent flash and the smell of burnt feathers , especially if it is a big bird that shorts across four or more insulators.
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OK then, a bird perches on a wire. You're using electricity in your house. There is therefore a complete circuit, of which the bird is a part. So he'll get a small current up one leg and back down the other then...... which would at least keep his feet warm!? ;D
:roflanim: :roflanim: :roflanim: Thanks womble, that really cheered me up :roflanim: :roflanim: :roflanim: :roflanim:
i could just picture it.......gawd i need a shrink :roflanim: :roflanim: :roflanim: :roflanim: :roflanim:
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That would apply if the bird had legs 100 mtrs apart.
I know, but I can't resist the thought of calculating out the heat input.
So, P= I^2R, substituting into ohms law gives P=R(V/R)^2, and for resistors in parallel, 1/Rt=1/R1 + 1/R2......
Drat, I'm stuck. Does anybody know the electrical resistance of a swallow?
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Sadly swallows are non-linear conductors whose resistance depends on the current/voltage and also whether they've been paddling in the sea before perching on the wires.
As it happens though, birds perching on wires at peak-load times could well be warming their feet - some cables operating near their design limit will have a significant temp rise above ambient.
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and i thought i was a nerd...
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(http://i228.photobucket.com/albums/ee62/johningham/bird_zpsc6b2728a.jpg) (http://s228.photobucket.com/user/johningham/media/bird_zpsc6b2728a.jpg.html)
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:roflanim:
Love the green wellies.
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RE: resistance of a swallow, African or European?
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Oh, er, I don't know....... AAAAAAAARGGGHH, Kaboom!!!!!
Hey Derby_menagerie, I'll throw them up, you hit them ;) .
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and i thought i was a nerd...
I think you have a lot of fellow sufferers on TAS, David :innocent:
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Birds like power lines because they like being high up and having an unobstructed view of prey or oncoming danger. Standing on a wire put them at no short term risk unless they have one foot on two lines with different currents. Then they catch fire and cause a fire. Longer term it does throw off their quantum time and cause mitochondrial inefficiency but it is not perceptible to the bird.......but if done over and over it will shorten its life. While on the wire, if the bird touches anything "grounded," meaning anything with no voltage, such as the earth's surface or the wooden pole (which is also grounded), the current would instantly flow through the bird's body to reach the ground, and the bird would be immediately electrocuted. When birds are standing on a single phase power line with both feet on the wire, they actually do get electric shock. However, it is in the nano-voltage range so they don't perceive any sensation but it does alter their SCN. Even though they do not complete a path to ground, they are in fact in parallel circuit with the power line. Since the power line has not 0 ohm of resistance, even between the bird's legs, some electric current is deviated into the bird and it gets fried. That is Ohm's law that is found in classic physics! To experimentally show it, you could replace the part of wire between the bird's legs with a Gigaohm resistor, and then observe what happens to the bird. It gets electrocuted. If it touches another phase wire it also gets fried. The power lines on poles are not insulated wires, i.e., they do not have insulation wrapped around them. They can’t! They would overheat under high load (current carrying) conditions. Overhead power lines are generally made of stranded aluminum conductors with steel reinforcing core wires (ACSR), although some older conductors are still copper. The insulation comes into play at the ceramic insulators that hold the wires away from the wooden or metal poles/towers. As long as the insulators are intact and relatively clean, the voltage potential is maintained and there is no path to ground. Birds are safe on electified conductors as long as they are only in contact with a single phase. Often, the larger birds, such as hawks and owls, will sit on pole tops. When they take off, their wing tips may brush across two phases, it is deadly for them and can cause forest fires. Since electricity always follow all the given paths, but how much current flows through those paths depends of their resistance of the circuit. Most of the current in a single phase high voltage wire stays in the wire and does not pass into the bird.