RE: buzz buzz buzz - I wonder why it does?

["Keith Doxey" <lists.diyha@xxxxxxx>]

Hi Nick,

 

Yes it is the current that kills but the mistake you are making is using it basing your calculations on POWER.

 

For a given power halving the voltage will double the current

 

 

240W @ 240V = 1A

240W @ 120V = 2A

240W @ 12V = 20A

 

When you receive an electric shock the voltage is applied across the RESISTANCE of your body. That is fairly constant and only changes according to the amount of moisture in or on the body. That is why water and electricity is often a fatal combination.

 

For DC it only takes few milliamps to kill you as it causes muscles to contract and as the current is constant the muscles wont release. For AC it takes quite a bit more as the current keep reversing and also has brief periods of zero.

 

If you take as an example, a person with dry skin and a body resistance of 50kohms then

 

@ 240V    240/50000 = 4.8mA

 

@120V    240/50000 = 2.4mA

 

@50V    50/50000 = 1mA

 

@ 12V    12/50000 = 0.24mA aka 240uA

 

I just tested my body resistance with my multimeter and got a reading of about 1Mohm with dry fingers, wetting the tips of finger and thumb made the resistance drop to about 40kohms.

 

One of the reasons I never wear rings or watches is because the last thing I want is a large lump of metal attaced to my skin to give a much improved contact area. >From the risk of shock, you can also get severe burns if a piece of jewellery comes into contact with live contacts.

 

The biggest danger from electric shock is when the current flows from one side of the body to the other as it crosses the chest and causes heart failure.

 

The one thing that really confuses me is that electricity can kill a living person but.....

.... electricity is used to bring a very recently deceased person back to life !!!!

Keith

www.diyha.co.uk
www.kat5.tv

-----Original Message-----
From: Nick Broughton [mailto:mail@xxxxxxx]
Sent: 20 April 2002 23:07
To: ukha_d@xxxxxxxSubject: RE: [ukha_d] buzz buzz buzz - I wonder why it does?

Keith

 

I thought it was current that killed, not voltage?  Static electricity produces very high voltages.

 

W=AV, so lowering voltage increases current to provide the same power to a the tool.

 

What am I missing in this argument?

 

Nick

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