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Re: For what it is worth....science lesson..
Posted by 'jimwhite' on 26 Jan 2013 @ 00:15

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jimwhiteJoined: April 2007
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A current of 30mA , through the heart (from contact point finger? to exit point foot?) can cause a fatality (death in the very young, infirm or very old, usually it's a shock and a lot of swearing). the shock disrupts the heart's rhythm and causes fibrillation which causes the disruption of the supply of oxygenated blood to the brain and collapse ensues. Defibrillators (a current through the heart are used to shock it back into rhythm). Huge currents 5A or more can cause the chest wall to spasm and clamp the heart preventing it from going out of rhythm and restarting normally once the initial overload has passed. However, would not recommend experimentation, since there would still be a heating effect.

The same current that leaves the LIVE (RED) of the generator will be the same amount/size of the current that returns after being used to blow up tyres etc. The difference between these 2 (or the RESIDUAL) should ALWAYS be zero. However, along the way some current may be diverted through a person and go to EARTH through the person. The returning current will therefore have "lost" some current and the difference will no longer be zero. If this difference (or Residual of the Residual Current Device) is greater that the set amount e.g. 10mA then the generator will be shut down / disconnected. This will stop the current going through the person and if shut down fast enough 40ms the person will survive.
The same principle applies to current drain through any other inadvertent leakage to earth i.e. wet films on bare wires, whiskas touching stuff, insulation not as good as it should be etc.

Voltage is the thing that forces electricity (amps) through objects ( conductors , pumps, lights etc). The higher the voltage the less current is needed to make things work.
The Earth (3rd rock from the Sun, ground) is at Earth potential = 0 volts. The convention is to link the neutral to Earth and then the voltage being used is "true" 240volts. However, if the generator is not "linked" to Earth then it's output voltage will be 240 volts + or - whatever it is at.
You can get a shock from a car door handle on a hot, dry summers day because the handle could be at 10 000 volts above Earth and you are the path to Earth that the electricity goes through to get to Earth.
So unless the generator is linked to Earth somehow it's output could be anywhere but is likely to be only be a few volts different to earth.

Of course , generators are not dc -steady 240 volt output - but ac but enough for today.

Message Thread:

RCD protection on a portable generator by 'PaulClarke' (23 Jan 2013 @ 9:15)

Re: RCD protection on a portable generator by 'Mark 71' (23 Jan 2013 @ 12:53)

Re: RCD protection on a portable generator by 'AndyOxfordshire' (23 Jan 2013 @ 14:01)

Re: RCD protection on a portable generator by 'ajc74' (23 Jan 2013 @ 15:34)

Re: RCD protection on a portable generator by 'PaulClarke' (23 Jan 2013 @ 16:19)

Re: RCD protection on a portable generator by 'PaulClarke' (23 Jan 2013 @ 16:24)

Re: RCD protection on a portable generator by 'itpro' (23 Jan 2013 @ 16:28)

Re: RCD protection on a portable generator by 'PaulClarke' (23 Jan 2013 @ 16:33)

Re: RCD protection on a portable generator by 'itpro' (23 Jan 2013 @ 16:43)

Re: RCD protection on a portable generator by 'colingray' (23 Jan 2013 @ 17:28)

Re: RCD protection on a portable generator by 'PaulClarke' (23 Jan 2013 @ 17:49)

Re: RCD protection on a portable generator by 'Mark 71' (23 Jan 2013 @ 17:21)

Re: RCD protection on a portable generator by 'moondog78' (23 Jan 2013 @ 17:48)

Re: RCD protection on a portable generator by 'colingray' (23 Jan 2013 @ 18:07)

Moondog78: What are your thoughts on... by 'PaulClarke' (23 Jan 2013 @ 18:15)

Re: Moondog78: What are your thoughts on... by 'colingray' (23 Jan 2013 @ 18:36)

Re: Moondog78: What are your thoughts on... by 'moondog78' (23 Jan 2013 @ 18:39)

Re: Moondog78: What are your thoughts on... by 'fatsam' (23 Jan 2013 @ 20:55)

Paul call my dad....Nt by 'BanzaiBoy' (23 Jan 2013 @ 21:23)

For what it is worth...... by 'PoppaAl' (24 Jan 2013 @ 7:56)

Re: For what it is worth...... by 'itpro' (24 Jan 2013 @ 10:12)

Re: For what it is worth...... by 'mdc67' (24 Jan 2013 @ 12:46)

Re: For what it is worth...... by 'colingray' (24 Jan 2013 @ 18:19)

Re: For what it is worth...... by 'PaulClarke' (25 Jan 2013 @ 8:56)

Re: For what it is worth....science lesson.. by 'jimwhite' << You are here!

Great replies - but no answers!!! by 'PaulClarke' (26 Jan 2013 @ 10:41)

Re: Great replies - but no answers!!! by 'itpro' (26 Jan 2013 @ 11:19)

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