Date   : Sun, 13 Sep 2009 12:17:14 +0100
From   : rs423@... (Mick Champion)
Subject: Leccy @ Acorn World '09

Jonathan Graham Harston wrote:
>> Message-ID: <4AA9582A.2070805@...>
>>     
>  
> Phill Harvey-Smith wrote:
>   
>> Jonathan Graham Harston wrote:
>>     
>>> 'cos electricity and water don't mix!
>>>       
>> Nope they don't because warter is generally a bad conductor, when pure.
>>     
>  
> It always gets me when I see the classic bathroom dangers cartoon
> of a child in a bath with a radio/hairdryer/toaster precariously
> balanced at the end. Surely, the easiest route for the electricity
> to flow is back out along the neutral? Even if the occupant picks
> up the said toaster, to get a shock you'd have to break it open and
> touch both incoming and outgoing conductors and prevent the current
> flowing through the internal wiring.
>   
All devices have a internal resistance (such as a radio mains 
transformer) or else there would be a dead short. So, this will impede 
the flow between the hot and cold wires.  When another resistance is put 
in the circuit such as bath water to ground, some of the power will 
route it's way back to earth through the waters impurities. What makes 
it worse is when it hits us, we are salty and conduct better than the 
water. Remember it's the volts that jolt, but the mills that kills. So 
long as the volts are high enough to break through our skin, we then 
become a circuit ourselves.  I think I'll stick to taking my battery 
operated DAB into the bathroom in future.


Remember in electronics, if you have a 10k and 22k resistor in 
parallel,  current will flow through both despite the easiest route 
being through the 10k. In our bath scenario yes it's true that less 
power will pass through us than the toaster? :-D , but still enough 
mills to kill? I wouldn't want to test it out. If you have an RCD, you 
*should* be okay though. I had a fault with my washing machine. I got 
the meter on it, and found out that less than 20 mA was passing back 
through the earth wire, yet it still tripped.


Mick




>  
>   
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com 
> Version: 8.5.409 / Virus Database: 270.13.91/2363 - Release Date: 09/11/09
09:15:00
>
>