"scott" <sco### [at] scottcom> wrote:
> >> Nope. As the Wikipedia article explains, there are sprung-loaded plastic
> >> covers that only move out of the way as the earth pin is inserted.
> >
> >  Is it guaranteed that the difference in potential between the earth pin
> > and the physical ground is always very close to zero?
>
> The Earth wires in your house (in the UK at least) are connected to the
> physical ground at your house, usually by being connected to the mains water
> pipe or some similar big lump of metal in the ground.  So I don't think
> there can be much of a difference, there is probably some building standard
> that gives limits on the resistance.  I assume these limits are set so that
> any potentially dangerous Earth voltage would result in the current in the
> defective device blowing a fuse.


do :)
In new builds you will often find a metal rod driven into the ground as an
earthing electrode.

--

Stephen

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Stephen wrote:


> do :)

Isn't that illegal?

> In new builds you will often find a metal rod driven into the ground as an
> earthing electrode.

"I think having a lightning conductor on a church represents an 
extrodinary lack of faith."

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Invisible <voi### [at] devnull> wrote:
> Stephen wrote:
>

> > do :)
>
> Isn't that illegal?
>

Yes and not very effective.


> > In new builds you will often find a metal rod driven into the ground as an
> > earthing electrode.
>
> "I think having a lightning conductor on a church represents an
> extrodinary lack of faith."

Is it not to protect the church from the devil ;)
A bit like a high tech gargoyle.

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Stephen wrote:

> Here are a couple of tips for everyone when working on live equipment. Wear
> insulating footwear and keep one hand in your pocket. That way the current is
> less likely to find a path through your body.
> 

I am not an electrician, so I know enough to be dangerous.
Actually, I studied electrical engineering - so I know enough to keep 
mostly safe.

I was thinking I would write about keeping a hand in the pocket, but you 
beat me to it.

I always have a hand in my pocket when routing wires in my main electric 
panel where I can't easily turn everything off.  It isn't enough to just 
keep a hand away - by instinct you will use it to grab on to something.



I've been lucky, I've never been hit with anything more than 110v


Tom

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Warp wrote:
> Orchid XP v8 <voi### [at] devnull> wrote:
>> Nope. As the Wikipedia article explains, there are sprung-loaded plastic 
>> covers that only move out of the way as the earth pin is inserted.
> 
>   Is it guaranteed that the difference in potential between the earth pin
> and the physical ground is always very close to zero?
> 

Some non-electricians will hook up the earth as a common - using it as 
the return path for the hot.

In this case the potential will vary with the amount of current on the wire.

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Tom Austin <taustin> wrote:
> Stephen wrote:
>
> > Here are a couple of tips for everyone when working on live equipment. Wear
> > insulating footwear and keep one hand in your pocket. That way the current is
> > less likely to find a path through your body.
> >
>
> I am not an electrician, so I know enough to be dangerous.
> Actually, I studied electrical engineering - so I know enough to keep
> mostly safe.
>
> I was thinking I would write about keeping a hand in the pocket, but you
> beat me to it.
>
> I always have a hand in my pocket when routing wires in my main electric
> panel where I can't easily turn everything off.  It isn't enough to just
> keep a hand away - by instinct you will use it to grab on to something.
>
>
>

I get nervous working over 5V Vcc.

reason I stopped working offshore. It was getting too dangerous.


waistband.


> I've been lucky, I've never been hit with anything more than 110v
>
>
A mere tingle :P
240 V is not too bad it hurts more but is bearable if it is just through your
hand. And most of the shock is just shock people do get used to it and can even
deliberately touch live connectors to test the voltage. The trick is to do it
fast and the pain level will tell you the voltage. The same way that I learned
to see how close to boiling water is by dipping my fingers into it (FAST). The
human body is very resilient.


Stephen

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> Some non-electricians will hook up the earth as a common - using it as the 
> return path for the hot.
>
> In this case the potential will vary with the amount of current on the 
> wire.

But I think that Buildings Standards require that the resistance to ground 
be low enough that for the Earth voltage to become dangerous, enough current 
must flow to blow a fuse.  Otherwise this kind of relatively common fault 
would leave metal cases of everything in the house electrified to dangerous 
voltages!

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> Yeah, some bathrooms have special "shaver" sockets which are weird 2-pin 
> connectors fused at 2A or something. Personally, I don't know about you, 
> but my bathroom is so tiny that you'd be just as well to go somewhere 
> else... ;-)

It appears that the forthcoming 17th editiion of the building regulations 
(aren't you excited!) in the UK will allow normal 13A sockets in a bathroom, 
if they are protected by a 30mA RCD and not too close to a shower/tap...

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scott wrote:

> It appears that the forthcoming 17th editiion of the building 
> regulations (aren't you excited!) in the UK will allow normal 13A 
> sockets in a bathroom, if they are protected by a 30mA RCD and not too 
> close to a shower/tap...

How in the name of God do you know that? o_O

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>> It appears that the forthcoming 17th editiion of the building regulations 
>> (aren't you excited!) in the UK will allow normal 13A sockets in a 
>> bathroom, if they are protected by a 30mA RCD and not too close to a 
>> shower/tap...
>
> How in the name of God do you know that? o_O

My mum asked me a while ago about putting a socket in her bathroom, so I 
looked into it then.  It appears that now you are actually allowed normal 
sockets in your bathroom (Wikipedia was a bit out of date).

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