High Voltage is Crazy!

So, does wood conduct electricity? Well, logic would suggest if the wood is wet (like a live tree) it probably does, but what about a piece of dry wood which has been in a house for dozens of years in an extremely dry climate?

Now there's no Earth shattering science breakthrough here, but it is kind of a fun story I think...

Of all the electrical conductors around you at any given moment, wood would seem rather low on the scale, right? Tonight I had a rather interesting experience which would suggest otherwise.

It seems mundane, I know, but my wife asked me if I would put away a casserole of mac & cheese when she went to bed. She's a professional chef so we have a commercial grade roll (i.e. HUGE) roll of cling (plastic) wrap in one of our cabinet drawers. Now many of us know, cling wrap is notorious for generating static electricity, right? Well, what I saw when I pulled some off the roll to cover the mac & cheese surprised even me!

The kitchen light was off so it was kind of dark. I opened the cabinet and pulled out the drawer to expose the cling wrap box. I pulled off about 1.5 feet of it (it's a large casserole dish) and thought I saw something under the drawer, like a blue light. I needed a couple more pieces, so this time I pulled off the next sheet and watched carefully. As I pulled the cling wrap off the roll (inside the box, inside the drawer), there was arcing between the drawer slide and the track on the cabinet. I thought it was a lark at first, but I needed more. So the next sheet I pulled off I did it real slow (less arc), then I pulled it faster off the roll (much bigger arcing). Wow! Made me grin.

As an engineer I work with electricity all the time. I always hear about crazy things electricity can do. Most of the voltages I work with are 480 up to about 5,200 VAC (sometimes some 35kV). Obviously safety is the highest order, but sometimes it's the simplest things which can make you think twice about why.

Static electricity is usually somewhere between 20kV-25kV. Just the fact that there was no metallic connection between the box of cling wrap and the drawer...it was interesting to see the electric field arc across the drawer slides. Granted the amperage was small (unlike work), but it doesn't matter.

Sometimes people ask about the difference between voltage and amperage...this was an example of voltage. Simple as it may be.

That's all.

a reply to: Flyingclaydisk

Good thing you remembered to
turn of the gas.



Yes wood as a conductor seems the less likely
suspect. And yet.

S&F

a reply to: Flyingclaydisk

My grandpa used to work at a grain elevator,and in his spare time,he used to shoot cat's with a bb gun.I always thought it was a bit cruel,til he explained why! Grain dust is explosive! Wheat dust,corn dust,it will go boom with a minor spark.Cat's fur makes static electricity,so shoot the cats! Why are there cat's at a grain silo?? Catching mice!

You can think of voltage as 'speed' of the electricity.

It's not accurate, but it works.


The faster it's going, the farther it can jump. High enough voltage and it'll arc- think lightning, or tesla coils.

Wood is an electrical insulator, so electricity won't flow through it- until it gets moving 'fast' enough. Same way a 9v battery can't zap your fingers, but it'll zap your tounge. A 48v phone cable will give you a jump start, though.

Well, there you go.
If it was DC you wouldn't have that problem. Blame Tesla. Oh. wait.


ehmmm.
When I was a kid I built a Van De Graf generator for a science project. I figure I got about 25kv out of it on a good dry day (dry being a relative term). It was bitchin.

My biggest science project was one day when I was 12 I walked across my bedroom carpet in a pair of dry leather soled cowboy boots. This was in Wyoming, and the humidity was about -5%. I went to turn on the light. I think my finger was about 6" away from the switch when a bolt of lightning shot out of my finger to the screw on the cover plate of the switch! I think my heart stopped, and it hurt like crap!

a reply to: Flyingclaydisk
Too humid in the tropics for anything like that. My generator could cross a 6" gap but the spark was pretty spindly.
Not even close to the hair sticky outy thing. But a tin foil spinner (ion driven) would go nuts. Fluorescent bulb would glow a bit.

My friends thought I was weird.

a reply to: Phage

Just your friends? Gosh, everyone thought I was weird!

LOL

I remember one winter in my college dorm, we had a serious static electricity problem with low humidity. I complained to my roommate about him turning on the light during the middle of the night. He had a small fluorescent lamp with two small bulbs about a foot from his bed, maybe only 8 inches to a foot. He said he wasn't touching it. Then he showed me it wasn't even plugged in. Then he lifted up his blanket and the light turned on for almost a whole minute.

When we slid off our beds, the static was so powerful it was painful. For a month we learned to pick up screwdrivers first and discharge the electricity before touching anything. I once accidentally knocked out the picture on my roommates tv for a few seconds attempting to turn the channel but it came back on. As an experiment, I touched the center of some big fluorescent light bulbs and lit up two thirds for a second or two.

I had a weather thing in my room and one day, the humidity dropped below 5%. I heard a crackling sound all around me while sitting on my bed. Not good I thought. I touched the cinder block wall next to my bed and could hear and feel static electricity discharging off of each finger and was able to repeat it just sitting there, finger by finger. Another neat thing I did was discharge myself, open up the doors and turn on the water faucet in the bathroom. Then I sat on my bed for a minute to get charged up. I got up and heard my footsteps as I heard static electricity getting discharged through my shoes on the tile in the hallway. Then I put my finger near the water coming out of the faucet and watched the stream of water curve near my finger. It would curve until I saw a spark from my finger to the water.

a reply to: orionthehunter

That's a pretty cool story!

You have such an arch because wood is such a poor conductor. The static arch occurred because the negative charge on the wood had no other way to return to ground. Even if it arched to wood, it would be because the surface of the other wooden object's surface was very positively charged with respect to the negative object.

Static electricity is weird. Over the past several years I've occasionally run into static electricity issues when nobody else was. Examples include building up electrical charges in a club, at church, at Walmart. The discharges occasionally hurt and are powerful. I'm not sure why I sometimes get surprised and shocked when touching water. I'm not sure what was going on but I noticed the issue mostly went away after giving blood. I wondered if having some excess iron contributed to the issue. If several others hear or see lightning from your fingers, you know you may have an issue.

I find it odd how my body easily accumulates so much electricity. I remember a few years ago cleaning up and folding up some plastic drop cloths up off my floor. Then when I went to flip the light switch, bamm. I got zapped so hard my brother heard it 50 feet away. It hurt like crazy too.

Has anyone else felt shocks touching holy water in church or touching water coming out of their faucets or touching touch screens or other objects in Walmart? I'm not sure how I keep accumulating electricity when others are not. Maybe more iron in my blood causes more electrical charges to build more easily.

orionthehunter, I'm amazed what you're putting up with....

you're special....

Static electricity is weird:

David Swenson of 3M Corporation describes an anomaly where workers encountered a strange "invisible wall" in the area under a fast-moving sheet of electrically charged polypropelene film in a factory. This "invisible wall" was strong enough to prevent humans from passing through. A person near this "wall" was unable to turn, and so had to walk backwards to retreat from it.

This occurred in late summer in South Carolina, August 1980, in extremely high humidity. Polypropelene (PP) film on 50K ft. rolls 20ft wide was being slit and transferred to multiple smaller spools. The film was taken off the main roll at high speed, flowed upwards 20ft to overhead rollers, passed horizontally 20ft and then downwards to the slitting device, where it was spooled onto shorter rolls. The whole operation formed a cubical shaped tent, with two walls and a ceiling approximately 20ft square. The spools ran at 1000ft/min, or about 10MPH. The PP film had been manufactured with dissimilar surface structure on opposing faces. Contact electrification can occur even in similar materials if the surface textures or micro-structures are significantly different. The generation of a large imbalance of electrical surface-charge during unspooling was therefore not unexpected, and is a common problem in this industry. "Static cling" in the megavolt range!

On entering the factory floor and far from the equipment, Mr. Swenson's 200KV/ft handheld electrometer was found to slam to full scale. When he attempted to walk through the corridor formed by the moving film, he was stopped about half way through by an "invisible wall." He could lean all his weight forward but was unable to pass. He observed a fly get pulled into the charged, moving plastic, and speculates that the e-fields might have been strong enough to suck in birds!

"Invisible Electrostatic Wall"
at 3M adhesive tape plant

a reply to: orionthehunter

It has a lot to do with what the soles of your shoes are made of. If leather...look out! Also has a bit to do with what clothing you're wearing; nylon and synthetics generate a lot of static electricity. I'd be pretty surprised if the iron in your blood has anything to do with it at all (and besides, it would have to receive the charge somehow).

Regarding water faucets, absolutely, waterlines are electrically bonded to Earth ground at home and building entrances. As a result a water faucet represents an excellent ground, hence the shock. (same reason you receive a shock from a light switch; it's grounded also).

a reply to: jadedANDcynical

I worked in solid rocket booster assembly facility for a project one time, and believe me...these guys took static electricity (and discharge of the same) VERY SERIOUSLY!!!

I can't imagine why!


The whole facility was a building within a building. The inner building was isolated from everything (except earth ground)Everything was grounded six ways from Sunday. Everyone had to wear anti-static suits with tethers attached to grounding bars (you had two tethers, one had to be attached to the next point before the first one could be removed if you were moving around). Humidity was controlled down to the nano-unit. Everything had to be metered for differing ground potentials before anything conductive touched anything else. You did not want to be within 50 MILES of this place if there was ever an arc!!!

Wood isn't exactly a conductor as such but moisture will reduce its characteristic resistance. Wood in your home will have 'normalised' to the ambient humidity of its environment which enhances the conductive property of it. If the wood had been fully dried out (eg vacuum oven dried) it would lean more to being an insulator but, being a carbon based material, it will still break down under high voltage stress sooner than a good insulator like xlpe.

Ever seen a dead tree get struck by lightning? it literally explodes as the internal moisture is vaporised (scary if you're anywhere near it)

So your wife started as a waitress, and then moved to the back of house to become a chef?

The more I hear about you guys, the more interesting you become.

a reply to: bigfatfurrytexan

Huh?

Oh, well, I don't believe I've ever stated my wife was a waitress, but as it turns out she was. I think you may be referring to another gal I was referring to by the name of Judy (whom was never my wife).

I'm not sure if this sheds light on anything but further confusion. Alas, it's a confusing world.

a reply to: Flyingclaydisk

Yeah, it was Judy. I thought you mentioned you married her.

Its only a confusing world between my ears, it appears. LOL

Around these parts its really hot and dry. So we don't get a ton of static electricity, although I do think there is a connection between the ridiculously iron rich soil and the dirt devils we get.