Re: Bizzare Blooper in Battlefield


"Ronnie Clark" <ronnie@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
wrote in message news:drj1vq$88k$1@xxxxxxxxxxxxxxxxxxxxxx
>
> "The Face of Po" <gkennington@xxxxxxxxxxxxxxxxxxxxx> wrote in message
> news:1138557130.11984.0@xxxxxxxxxxxxxxxxxxxxx
>> I was hanging out with the cool kids in rec.arts.drwho when
>> Chancellor_Goth got out a spraycan and scrawled the following:
>> > "Dburns2006-B" <dburns@xxxxxxxxx> wrote in message
>> > news:drilgh$p6t$0@xxxxxxxxxxxxxxx
>> > >
>> > > "Chancellor_Goth" <eye@xxxxxxxxxxxxxxx> wrote in message
>> > > news:drikms$tu9$1@xxxxxxxxxxxxxxxxxxxxxx
>> > >>
>> > >> "Ronnie Clark"
>> > >> <ronnie@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote
>> > >> in
>> > >> message news:drict3$lgf$1@xxxxxxxxxxxxxxxxxxxxxxx
>> > >>>
>> > >>> That must be a very hot fire to fry me. Or are you trying to imply
> to
>> > >>> that I
>> > >>> would be electrocuted? In which case, I think such a demonstration
> to
>> > >>> show
>> > >>> that that is not the case is even more in order.
>> > >>
>> > >> Idiotic troll. People have died when electrical items fell in their
>> > >> bath, the last one I knew of was a friend's mother who died when a
>> > >> portable TV fell in and she got 240 volts through her.
>> > >>
>> > >> PLONK.
>> > >
>> > > I was wondering how long it would take before you finally tossed
>> > > Clark
> in
>> > > the killfile.
>> >
>> > With any luck he'll test his theory by having a bath with the National
> Grid.
>> > 240 volts is no fun.
>>
>> As any fule (or anyone who paid attention in physics lessons) kno, volts
>> don't kill you, amps do. Not that this makes dropping a telly in yer
>> bathtub safe, or anything.
>
> "It's volts what jolts, amps what kill". Unless using electricians'
> gloves,
> always work one handed on high voltage (55+ volts) equipment. 55V from
> hand
> to hand, through the heart, is enough to cause the fatal current of 30mA
> to
> flow.
>
> See, the thing is, with my degree in electrical engineering, I do actually
> know what I'm talking about. I know precisely how I could safely immerse
> myself in a bath of water and have someone "throw in" a fire and be fine.
> I
> also know how I could kill myself with a single AA battery. As I tried to
> point out at the beginning of the discussion, the behaviour of electricity
> is defined and quantifiable. If you want to stay alive, just don't allow
> 30mA to pass through the heart. And contrary to the document Chancellor
> Goth
> provided, it is actually insufficient earthing of the plumbing that can
> cause fatalities. There are basically three circumstances in the instance
> of
> an electrical appliance falling into water:
>
> 1 - Live connection contacts water first. Insufficiently earthed plumbing
> causes electricity to choose the human body as a current path (assuming
> person is not just immersed in water, but also has parts of body in
> contact
> with other areas outside of the bath). Human is electrocuted, fuse / MCB
> may
> or may not blow as the high resistance of a human being may not allow
> short
> circuit to be set up, RCD will blow too late.
>
> 2 - Live connection contacts water first. Sufficiently earthed plumbing
> causes electricity to use water between contact point and and plumbing as
> current path. If human is outside of this path, human is safe. Fuse / MCB
> will blow as current flow is short circuited, RCD will blow.
>
> 3 - Neutral connection contacts water first. Earthing of plumbing
> irrelevant. The presence of the neutral connection before the live hits
> will
> present the shortest current path possible, human is safe. Fuse / MCB will
> blow as current flow is short circuited, RCD will not blow if plumbing is
> insufficiently earthed.
>
> In countries where a balanced supply (such as various American
> installations) is used, there is no neutral, so #3 above does not apply.
> However, such systems allowing the halving of supply voltage. The 110V
> supply can effectively be split into -55V and plus +55V (when voltages are
> at peak values!). This is far safer, as 55V is generally accepted as the
> maximum safe voltage before accidental electrocution can occur (though for
> smaller animals or children, the 'safe' value is obviously much lower). In
> most undergraduate labs, there are notices reminding students that if you
> are working on more than 55V, you must always have someone else with you.
>
> I have "live-side" wired many an installation, often coming into contact
> with 230V (not the 240V which people still think we use in Britain). But I
> knew what I was doing, and have never so much as received a jolt (though
> that time a faulty DVM short circuited when testing a mains socket was
> interesting - bye bye DVM!).
>
> Anyway, I never advocated anyone jumping into baths and having mates
> throwing fires at them. All I tried to point out is that Sophie Aldred was
> in no danger of electrocution. She was totally immersed in water, in
> contact
> with nothing that the water was not in contact with, and no conduction
> path
> through her was present - until, ironially, she was grabbed and pulled
> out.
> That was actually quite dangerous, electrically, because if the stage
> hands
> were in contact with earth, they could have become a conduction path.
>
> The basic principle that you don't mess with electricity unless you know
> what you're doing always applies.
>

It should also be noted that water does not actually conduct electricity.
It's only once the water contains impurities that it becomes a conductor.


.

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