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I Forge Iron

Lightning Strike On An Anvil


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We just had a storm pass through here with quite a light show. That got me to wondering what effect lightning might have, if any, on an anvil.
Besides the one inside I keep one out in the back yard too. It sits on a wooden base made from a pressure treated 6"x6" cut and glued up to form a 12"x12", that sits on a 2" thick concrete paver.
So i was thinking, since it is a fairly sizable hunk of iron just sitting out in the open that it might attract a bolt.
Would the wooden pedestal effectively insulate it?
If an anvil did take a strike would it suffer any ill effects?

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that all depends, to many unmentioned factors that can effect the outcome. Do you understand the concept of induction heating ? on the other hand it could have passed through with no effect, or it could turn it into a magnet. is this something you plan to try? if so let us know how it turns out.

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Being insulated from the ground I suspect that it would melt. The reason houses have lightning rods is so the electricity can travel from the house and into the ground and dissipate. Having your anvil insulated with wood timbers and concrete most of the electricity would stay in the anvil and make it heat way up. Theoretically you could attach a metal rod to the anvil and have it run into the ground 4 or 5 feet to help dissipate the electricity from a lightning strike. ...........BUT if you have any trees or building with in 10 or 20 feet of the anvil I highly suspect that lightning would strike one of those first being that they are much taller.

I guess you could mount your anvil on the top of a 20 foot wood poll in the middle of a field, that would probably get hit sooner or later and we could find out for sure what would happen, call it science. What ever it was it sure would be a sight to see.


but all in all I dont think you have lots to worry about with your anvil outside, maybe a little rust

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An anvil on a wooden stump is unlikely to attract an anvil strike, because it is insulated from the ground. If you really want a lightning strike you'd need to put it on a metal stand in the middle of an open area.

Lightning rods are connected to the ground in order to allow electricity to pass to the ground without damage to the structure. They are mounted above the highest points on a building and they have sharp tips to encourage the concentration of the static charge. Aside from a sharp tip on the horn, your anvil is quite unlike a lightning rod.

Heat is generated when electricity encounters resistance: iron is a much better conductor than the wood stump, so in the unlikely event of a lightning strike to your anvil I would expect the stump to be damaged rather than the anvil. Iron and steel are relatively poor conductors compared to aluminum or copper but I think the anvil would be alright. In addition a larger diameter wire has less resistance than a smaller wire and an anvil would be a very large, but very short wire.

Induction heating is the result of high frequency variation in a magnetic field, a lightning strike is large pulse of electricity actually passing through the anvil, so it's not quite the same thing. Resistance heating is likely to be a larger factor.

My guess is that the anvil would be fine.

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Being insulated from the ground I suspect that it would melt.


How would the current have any effect if it was isolated? if there is no path to ground then there is no circuit. fciron was correct in his statement of "An anvil on a wooden stump is unlikely to attract an anvil strike, because it is insulated from the ground"
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Aluminum aircraft in flight take lightening strikes near daily with little ill effects to the aircraft, the electronics, or the occupants. The wet stump is a fair conductor in a storm, and is part of why trees get struck regularly. I doubt the anvil would be affected, but the stump may or may not suffer.

Phil

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Phil, Trees certainly take damage from lightning strikes, so wet wood can't be that great a conductor. :P I believe much of the damage actually comes from water being explosively vaporized inside the tree, which is pretty cool if it's true. Less water inside an anvil stump, so the current might travel over the wet surface, well beyond my pay grade at this point.

Who's got a big field and some anvils to run an experiment? :lol:

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Thing is lightning doesn't need good conduction because the voltage is so high. Like a spark plug, it can jump to ground. The voltage in a lightining strike is orders of magnitude higher than that of a spark plug coil.

As to the effects on the anvil, I couldn't guess and would asume each situation to be unique in any event.

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back in the late sixties,went out to an old station down in the riverina part of new south wales,there was a drag chain they used 50 years before that was strung between 2 pine trees,this chain had 5 inch links and was 150 feet in length,lightning had struck the chain and welded into a solid mass ,trees had gone long ago ,power indeed in nature

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Ha Ha! You guys make it sound like I am trying to get my anvil struck! I was just wondering what might happen if it did. I suppose the worst outcome would be the face becoming separated.
Now that glen56 mentioned that large chain being welded together I can picture somebody here trying to harness that force and use it in the shop... :huh: (not a good idea!)

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I can totally see chain welding up if struck by lightning, the contact area between the links is relatively small, so there would be more resistance and heat there. Just like when something arcs on the layout table if there's poor contact. Dang, a thunderstorm just ended here. :lol:

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Ha Ha! You guys make it sound like I am trying to get my anvil struck! I was just wondering what might happen if it did.


The odds of it being struck are astronomical............But those odds can come up..........Best case scenario might be a religious icon gets burned into the face, I'd love to see THAT on Ebay ..........:lol:
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Lightning's pushing enough voltage to ionize a few miles of atmosphere. To put that in perspective, it takes ~ 40,000 volts to arc across a 1/8 inch air gap. Put another way you aren't insulating against that if it decides your anvil is the path of least resistance. If it did get hit I expect your stump would suffer for it but I imagine the anvil would come through just fine.

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The wood Will Not Insolate the anvil the bolt should traval right through to the ground. It might leave a small bern mark where it enters and exits. The Drewed is right about the stump it would probly bet blown to bits. I am an Electrical Apprentice and my Dad is a Electrical Contractor.

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Our house was struck by lightening. It followed a stubbed off old plumbing stack down from the roof to the basement and then jumped over to a copper cold water line. The arc blew a hole in the copper line---probably the localized arc + steam pressure behind it.

My guess: it would leave an arc scar in the anvil, Might heat it enough to draw temper on it.

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Actually 120 volts can arc up to 10 feet given the right conditions. (one of many unusual questions covered for the Electrical Journeymen Exam)


For values of "right conditions" that involve the conductor carrying several orders of magnitude more than 120 volts.

http://en.wikipedia....ki/High_voltage

Relevant passage: "The dielectric breakdown strength of dry air, at Standard Temperature and Pressure (STP), between spherical electrodes is approximately 33 kV/cm"

So to ionize a path (required first step for an arc to occur) you're looking at a minimum of just over 300,000V to initiate the arc.

Also worth pointing out my initial figure was incorrect, it's more like 10kv to arc across an 1/8 inch gap.


Wikipedia is not a reliable source for any disertation. NEC states 120 volts 10 feet.
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The odds of it being struck are astronomical............But those odds can come up..........Best case scenario might be a religious icon gets burned into the face, I'd love to see THAT on Ebay ..........:lol:



Lets see the add would read...

"RARE anvil with markings possibly made by the Greek gods, perhaps 4000 years old"

Someone would probably try to pull that! LOL


I've got no clue about electricity except that it hurts when it gets touched and it's a pain to deal with when you are trying to get trailer light to work.

I second the motion that one of these guys with too many anvils should conduct a "scientific experiment for the betterment of smithkind!"
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Well the Langmuir Lightening lab is in my neck of the woods; but I'd be hesitant to use one of *my* anvils! (though I'm tempted by my faceless 1828 William Foster...)

http://www.ee.nmt.edu/~langmuir/introduction.html

It's an interesting trip up there a switchbacked one lane gravel road with every tree alongside the road showing signs of impact and every good sized tree showing signs of lightening strikes. You go from the hot dry valley up to a cool alpine meadow...

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