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Topic: Electrical Safety (Read 14096 times) previous topic - next topic

fungus


If no electricity reaches the heart then you only have to worry about burns.


Incorrect.  If it can cook a hot dog... http://www.evilmadscientist.com/2007/cooking-hot-dogs-via-electrocution/ ...it can cook internal organs.  And cooked internal organs generally have trouble functioning correctly.


Being cooked is a type of burn, isn't it...?
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

cjdelphi

One could argue that cooked is merely an instrument in which heat is produced to be able to cook with?

InPhase277

Hello! First post, so please forgive any infractions of forum etiquette!

I would say that for any project that involves the potential for lethal current to flow in a body of water requires not merely trying to limit the current, but to detect the flow and disconnect power automatically. Americans and Canadians call it a GFCI, Europeans and Australians call it an RCD. Whatever you call it, it is absolutely, positively REQUIRED on the high-voltage mains supplying the equipment.

Of course, various levels of power supply isolation may cause the stray current to go unnoticed by the mains device, but GFCIs are available in many voltages, and probably wouldn't be too hard to construct from available components. The basic idea is to measure the current leaving one wire of a power supply and compare it to the current returning to it on the other. If they are equal, no stray current is flowing. If the current leaving one wire is NOT equal to the current returning, there must be another path outside the normal intended circuit. One or two hall effect sensors could be setup to monitor this pretty easily.

Peter_I


Hello! First post, so please forgive any infractions of forum etiquette!
....


Welcome!

When you have something relevant to say, it can never be a breach of forum etiquette.


I like RCD's.
They have saved me a couple of times.
"Nothing is foolproof to a sufficiently talented fool"

Coding Badly

Being cooked is a type of burn, isn't it...?


So it is.  My apologies.

polymorph

60Hz disrupts the heart and 50Hz doesn't? I have a hard time believing that slightly lower frequency makes such a large difference.

I have heard that AC, 50 or 60Hz, is more likely to cause fibrillation and therefore death than DC, because DC is more likely to just cause the heart to lock up until after the shock ends. Subject to damage from heat, of course.

Quote
Also, my mantra has been Volts Hurts, Amps Kill.  Voltage alone can still kill you, but it requires being at extremely high voltages (At least 20kV, though this is a guess, I know that I've watched a coworker get shocked by about 15kV without lasting harm, though it hurt) and usually results in a major explosion where the concussion kills you.  However, that is assuming no current.


This is a dangerous thing to say on any forum with newbies. As has been pointed out, 12V can shock you. If you were to pierce the skin in two places, say both hands or a hand and opposite foot, 12V could electrocute you (electrocute = kill, shock is if you survive).

Drop a wrench across the 240Vac line coming into your house, you'll see an arc flash with a concussion that can kill you and set nearby flammables ablaze. No way, shape, or form does it require "at least 20kV".

Your coworker was hit with, let me guess, a neon sign transformer? Those are current limited. As low as 10mA. FYI, there is no such thing as voltage with no current.

Look up arc flash on Youtube. In one case, there is a story of a worker who thought he was measuring 440Vac and put the wrong meter across a 2kV line. The resulting arc flash jumped from the meter to him and then across the lines, set his clothes on fire heat to toe, blew him back into the wall, and eventually killed him a day or two later.

Once an arc forms, the resistance is relatively low. Your flesh, once you get beyond the skin, has only a hundred ohms or so of resistance, even from one arm to another. I did some testing with a current limited high voltage power supply that I designed and built. And that is at very low currents. At higher currents, as someone pointed out, cell walls rupture and the resistance goes down.

And even with relatively casual contact, 60V can do you in. Get a hand locked in place by the current, and you get to hang on the wire and slowly cook to death. Or muscular reaction throws you into something, causing secondary injuries that may be fatal.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

GoForSmoke

Voltage without current, otherwise known as static electricity....
1) http://gammon.com.au/blink  <-- tasking Arduino 1-2-3
2) http://gammon.com.au/serial <-- techniques howto
3) http://gammon.com.au/interrupts
Your sketch can sense ongoing process events in time.
Your sketch can make events to control it over time.

sensai


Rainwater will have a little dust in it, it's not pure.


Correct but parts per million makes the dust speck in each drop of rain non applicable.
I actually tested this as a kid in grade 5/6.
perhaps with all the chemtrails these days it might produce a different effect. Maybe I will try it again,, if it would rain and not snow for a day or two.

GoForSmoke

Melt the snow, but sweep the top layer off first before you collect any.
I am sure that once power is applied that the small impurities will find an electrode quickly enough, maybe stick?
Pure water has a dielectric constant of 81 where air = 1.

Chemtrails? That's what clueless people who see contrails call them. I've seen one video where a California woman is showing the rainbow here lawn sprayer in making on a bright, sunny day. But to her it's not a rainbow, it's chemicals in the water supply just like the chemtrails chemicals! It's a huge plot to kill us all, not natural in the slightest! What a dizzy bitz!

About 30 years ago if not longer there was enough acid in acid rain to slowly kill trees. Today the rate of burning is higher, because when you're running out of something the thing to do is use it up faster and faster.
1) http://gammon.com.au/blink  <-- tasking Arduino 1-2-3
2) http://gammon.com.au/serial <-- techniques howto
3) http://gammon.com.au/interrupts
Your sketch can sense ongoing process events in time.
Your sketch can make events to control it over time.

polymorph

Quote
Voltage without current, otherwise known as static electricity....


Voltage requires charge displacement.

Why do you think you go "ouch!"

So-called "Static" electricity is just a build-up of voltage through charge separation. Lightning is "static" electricity. Within the realm of everyday life, I had a car that would just about knock me on my behind on dry days as I was getting out.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

InPhase277


Within the realm of everyday life, I had a car that would just about knock me on my behind on dry days as I was getting out.


I learned to keep my hand on some part of the metal as I slide out. This allows a small current to flow over the time it takes to get out of the car instead of one enormous current when you shut the door. Insulation-blowing machines can also create giant 6" sparks from their hoses on dry days. It is quite surprising when you walk too close to one to say the least.

GoForSmoke

I got into static back in school over 40 years ago though I never built a generator.
Voltage is electrical potential.

If you work in a place with compressed air to run machines with, it's got a little oil in it, then take a plastic bowl and give it a good spraying. Then find a victim, smile, point into the bowl and say "juice" but don't say touch or not, let them stick a finger in to show you there's no juice in that bowl.  ]:D

1) http://gammon.com.au/blink  <-- tasking Arduino 1-2-3
2) http://gammon.com.au/serial <-- techniques howto
3) http://gammon.com.au/interrupts
Your sketch can sense ongoing process events in time.
Your sketch can make events to control it over time.

Peter_I


I learned to keep my hand on some part of the metal as I slide out. This allows a small current to flow over the time it takes to get out of the car instead of one enormous current when you shut the door. Insulation-blowing machines can also create giant 6" sparks from their hoses on dry days. It is quite surprising when you walk too close to one to say the least.


I do exactly the same when the weather is dry, otherwise I can draw a spark that makes my arm buzz to the elbow!
:smiley-eek:

I actually think, that I and the car work as an electrophorus, unless the electrons are allowed to flow back slowly.

And in dry weather, I touch the door handles at work with my keys or a penknife before opening the doors at work. I can draw a couple of cm long sparks on a "good" day.
"Nothing is foolproof to a sufficiently talented fool"

cjdelphi

how about attaching a small neon bulb to the car, to absorb any static build up?

polymorph

How would you attach the bulb?
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

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