Gallery, Projects and General > How to's
How To Wire a Plug
John Hill:
--- Quote from: Darren on July 22, 2009, 06:11:24 PM ---So what happens when you grab a live whilst standing in the shower then?
Tell you what, how about you disconnecting your earth John and giving us a demo, be sure to video it though.... :lol:
Earth systems were developed for a reason.
--- End quote ---
If there was no circuit between the shower and the supply I would be quite OK, that is the point. Isolation is isolation.
In the PME and MEN systems one of the 'lives' is connected to the shower already! Back at the transformer one of the secondary taps is connected to earth but if it was not there would be no potential between either and earth and that is the priciple of protection we used to get from an isolation transformer.
Earth systems were developed to protect against the case where one leg may have been accidently connected to earth, a situation that would go undetected but at the same time make the other leg lethal to the touch of anyone in an earthed situation. So, they deliberately earth one leg which halves the problem and provides a mean for a protective fuse to blow if the other leg gets grounded too.
In the PME and MEN systems it is still not safe to touch the ungrounded leg (phase) in the shower as it WILL BE THE PRESENCE OF THE EARTH CONNECTION THAT KILLS YOU!
As far as standing in the shower goes it is quite possible that Mr Blindbird's house is actually safer than yours!
Darren:
The simple fact is that power stations do now earth one phase at source.
But even if they didn't there is still potential between two phases as they are "out of phase with each other"
Otherwise nothing would work on electricity.
Grounding one phase simply gives the safety devices something to work with.
But I know what you mean by isolation, it's why birds can sit on high voltage wires as live to squawk the tale... :lol:
Linesmen are also safe up there, they sometimes even have carts to pull themselves along from one pylon to the next to save climbing up and down constantly.
It doesn't matter how you look at if, electricity and living tissue do not mix very well if you give it a path, which is what earth does so I guess you have a very valid point.
Mr blindbird:
Yes,we're supposed to have grounding...since a while,but in fact,all the old houses(like mine that dates from before there were made regulations about grounding),are allowed to stay in orriginal shape,on one VERY strickt condition;nothing of any wiring may be changed,i gues that's got to do with the change from this old and till some point safe system to a half new system where the grounding is only in a part of the house.
As soon as i would change a single socket with a new one and let them know,that would be the most expensive socket nown to man,cause it would result in a forced by law completely rewiring the house :zap:
That was also the reason why i couldnt get me a lathe so easy,it had to run on 220,if i wanted the company to place 380,i'd have to rewire the house :bang: and it was up till resent that i discovered they make these chinese lathes for a fair price that run on 220.By the way...i was clever enough to make sure no wires are in the neighberhood of my shower :lol:and even if there would be one i sure wouldnt tuch it :zap:
Darren:
Sounds like a very difficult position's to be in, I bet you have extension leads everywhere !!!
Mr blindbird:
That's ok,I'm used to it as i been living here all my life,moving is realy not my thing and yes,there are a LOT of extention leads...behind the sofa's,under the carpet,hell,there are even extension wires comming from extention wires :lol: but i always make sure i dont overload the lot.
That wouldnt be possible either as the main breaker in my cirquit box is 20 amps :scratch:.
the minute i put on 2 apliances the same time,the main will jump :lol:
But never the less,i think your tip is verry handy,as when in the future i need to fix a plug at work or anywhere else,i'll make sure the ground will be longest,i had seen it before but never questioned it why,now thx to you i understand why.
Hey wayt...what's with my plug of my pc here...??looks like it came loo :zap: :zap: :zap: sssssee :bugeye: o dear...do i smell burned pork meat here? :D
Danny
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