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I did just that a few years ago on a 12v battery on my 4WD to create some sparks to light a bit of paper to light a fire when I was in the middle of nowhere and had no lighter or matches. Was spectacular but I was holding on to the spanner and got no shock.......???????

 

Lucky, this could have been a Mt Gay winner covered in acid or splattered in lead.

 

Next time try a steelo (i think they're called) mesh scrubbing thing. Hold that over a 6V battery terminals and it'll start to glow, the rest you'll figure.

 

Could well have been a candidate for the Darwin Awards if things had gone pear shaped :lol:

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Don't believe a small DC current will do you much harm. A small 50Hz current near the ticker - not good. Exact opposite effect of a defib. Best reason to have an RCD on everything.

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It is the DC component of any Voltage that actually Kills. Even AC has DC. It just swaps polarity is all. DC Voltage causes your mussles to contract. With AC, they contract and release and contract again with every increase in Voltage. So mains AC being 50hz, your Muscles do this 50 times per second. The contraction time is when you feel pain. With DC, they contract only once and remain contracted. You don't feel pain like you do with AC, apart from with a high enough Voltage, your muscles contract so hard that you suffer from the pain of strain of the contraction. DC across your heart effectively stops your heart in a contracted position. The heart actually has 2 movements to a beat, but an electrical shock causes all the heart to contracted and not just one chamber. You don't tend to stay concious for long with a stopped heart. AC across your heart causes it to go into fribulation. But you can actually stay concious for a little longer because the heart is still moving just enough blood....sometimes. They use DC to restart your heart, but shocking it and causing it to contract just enough to get it to start in it's cycle again.

With a severe enough elelctrical shock, a great deal more damage can be done to various components of the heart. It has also been commonly known for people that have recieved a major electrical shock, to seem OK and then have a major heart attack several hrs later.

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It is the DC component of any Voltage that actually Kills. Even AC has DC. It just swaps polarity is all. DC Voltage causes your mussles to contract. With AC, they contract and release and contract again with every increase in Voltage. So mains AC being 50hz, your Muscles do this 50 times per second. The contraction time is when you feel pain. With DC, they contract only once and remain contracted. You don't feel pain like you do with AC, apart from with a high enough Voltage, your muscles contract so hard that you suffer from the pain of strain of the contraction. DC across your heart effectively stops your heart in a contracted position. The heart actually has 2 movements to a beat, but an electrical shock causes all the heart to contracted and not just one chamber. You don't tend to stay concious for long with a stopped heart. AC across your heart causes it to go into fribulation. But you can actually stay concious for a little longer because the heart is still moving just enough blood....sometimes. They use DC to restart your heart, but shocking it and causing it to contract just enough to get it to start in it's cycle again.

With a severe enough elelctrical shock, a great deal more damage can be done to various components of the heart. It has also been commonly known for people that have recieved a major electrical shock, to seem OK and then have a major heart attack several hrs later.

 

G'day Wheels & 'team'. Oh & Thank you Dr. Spock, in real time. Sure hope you've got all that info correct for all our sake's. Sounds the 'real deal'. It's the first & only time I've read all that explained in simple lay-mans term. Thanks bloke. Y'all have a great day over there & let us know what are all the goodies at the boat show. james

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I was working from recall, so decided to consult Wikipedia (sections are quoted below). According to my calcs:

 

For 50hz AC, you typically need at least 72V (60mA*1200Ohm) for lethal fibrillation of a susceptible person (the low 5%)

For DC you typically need at least 300V (300mA*1000Ohm) for lethal fibrillation of a susceptible person.

 

You should be able to feel a something with currents as low as 1mA for AC and 5mA for DC. For the average person these equate to AC voltage of about 3V and DC voltage of about 15V.

 

According to Wikipedia:

 

{residual current devices] are designed to prevent electrocution by detecting the leakage current, which can be far smaller (typically 5–30 milliamperes) than the currents needed to operate conventional circuit breakers or fuses (several amperes). RCDs are intended to operate within 25-40 milliseconds, before electric shock can drive the heart into ventricular fibrillation, the most common cause of death through electric shock. In Europe, the commonly used RCDs have trip currents of 10–300 mA.

 

From wikipedia (on Electric Shock):

 

Ventricular fibrillation

 

A domestic power supply voltage (110 or 230 V), 50 or 60 Hz alternating current (AC) through the chest for a fraction of a second may induce ventricular fibrillation at currents as low as 60 mA. With direct current (DC), 300 to 500 mA is required.[2] If the current has a direct pathway to the heart (e.g., via a cardiac catheter or other kind of electrode), a much lower current of less than 1 mA (AC or DC) can cause fibrillation. If not immediately treated by defibrillation, fibrillations are usually lethal because all the heart muscle cells move independently instead of in the coordinated pulses needed to pump blood to maintain circulation. Above 200 mA, muscle contractions are so strong that the heart muscles cannot move at all.

 

and

 

"Body resistance

 

The voltage necessary for electrocution depends on the current through the body and the duration of the current. Ohm's law states that the current drawn depends on the resistance of the body. The resistance of human skin varies from person to person and fluctuates between different times of day. The NIOSH states "Under dry conditions, the resistance offered by the human body may be as high as 100,000 Ohms. Wet or broken skin may drop the body's resistance to 1,000 Ohms," adding that "high-voltage electrical energy quickly breaks down human skin, reducing the human body's resistance to 500 Ohms."[10]

 

The International Electrotechnical Commission gives the following values for the total body impedance of a hand to hand circuit for dry skin, large contact areas, 50 Hz AC currents (the columns contain the distribution of the impedance in the population percentile; for example at 100 V 50% of the population had an impedance of 1875Ω or less):[11]

Voltage 5% 50% 95%

25 V 1,750 Ω 3,250 Ω 6,100 Ω

100 V 1,200 Ω 1,875 Ω 3,200 Ω

220 V 1,000 Ω 1,350 Ω 2,125 Ω

1000 V 700 Ω 1,050 Ω 1,500 Ω"

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...one of the most important considerations of "body shock" is step potenial. (Yeah I did tree clearence of power lines for a few years)....puts you right amongst it. 240/22000/66000 volts. Standard Oz domestic street level transmision.

 

Carbon in the patten of the steel belts in the tyres on the outside after an ooops...enough said.

 

Wheels can probaly explain much better than me what this means and why the seemingly silly statement of "stand on one leg" actualy means quite a lot with a high voltage into ground (or water) injection means....

 

It has serious life or death consequences if you are going to extract someone who is "hooked up" without you being fully insulated.....

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KM was watching me at the lathe the other day and I was standing with one hand behind my back. He laughed and muttered something, but it was a stance that we were taught when servicing TV's. Especially the older "live chassis" designs. You were taught to take measurements with one hand, so that if you ever did get a zap, which you shouldn't be able to, but if you did, then the current never flowed across your chest. I really believe that is the one reason why I survided the 26Kv belt. If that went across my chest, I would most likely have been unconcous. When training, after one or two good belts, you learned "techniques" pretty damn quick and once learned, they kind of stick with you.

this may not be actually true in reality, but I have always wondered if it was also real life, but I remember seeing a film once about a guy learning to defuse Bombs. The circuits he learn't to defuse would give a damn good belt if he did something wrong. Hell of a way to take something very serious.

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I did just that a few years ago on a 12v battery on my 4WD to create some sparks to light a bit of paper to light a fire when I was in the middle of nowhere and had no lighter or matches. Was spectacular but I was holding on to the spanner and got no shock.......???????

 

Lucky, this could have been a Mt Gay winner covered in acid or splattered in lead.

 

 

:lol: :lol: :lol: You don't sound even nearly distraught enough about this for my liking!!! Anyway, how would you all decide if/how my as yet unclaimed bottle of Mt Gay would be divied up...........????????????? :lol:

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