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'[OT] 240V anywhere'
1998\07\23@011837 by tjaart

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It seems like we have many heavy current experts
around, so I can ask a question that's been with me
for a while.

Why do heavy current appliances (220V over here)
only burn the 'live' contact in the plug and not the
neutral contact. It is AC, right?

If you can answer this question, you'd be answering
one of life's two most puzzling questions for me.

--
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Tjaart van der Walt
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1998\07\23@070607 by jlepine

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The answer is IN the question.  The "live" leg has voltage on it
(arching).  The neutral is by definition at or near ground.

1998\07\23@073515 by tjaart

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Joe Lepine wrote:

> The answer is IN the question.  The "live" leg has voltage on it
> (arching).  The neutral is by definition at or near ground.

I thought about this, but it is AC. Besides, how does this
pin know it is close to ground and therefore not supposed to
get hot?

--
Friendly Regards

Tjaart van der Walt
tjaartspamKILLspamwasp.co.za

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1998\07\23@074343 by jlepine

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Maybe I don't know what you mean by saying "but it is AC"
Could you please elaborate?

1998\07\23@122308 by Peter L. Peres
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On Thu, 23 Jul 1998, Tjaart van der Walt wrote:

> It seems like we have many heavy current experts
> around, so I can ask a question that's been with me
> for a while.
>
> Why do heavy current appliances (220V over here)
> only burn the 'live' contact in the plug and not the
> neutral contact. It is AC, right?
>
> If you can answer this question, you'd be answering
> one of life's two most puzzling questions for me.

 I don't know why, but it's true. Here we have mandatory fault current
trippers (tiled floors everywhere + hot & wet = first touch is the last
one), so the explanation that the ground leakage through the 3rd prong
removes the connection arcing at connect/disconnect if the hot prong
touches first/separates last fails.

 However, I have a theory that is more or less chemical. I believe that
the live prong sees a higher potential (even AC) over ground than the
other prongs, and somehow this helps it build a thicker oxyde layer, which
in turn causes more resistance in it in time, vs. the other prongs. The
process is self-amplifying, with each connection making things worse.
Alternately, the air and debris trapped in the copper on the live prong
are 'more' than on the other one. Is this too far fetched ?

 You all know what amount of dirt collects on HV cables, AC or DC, in
time.  Ok, 220 V is not HV but then it takes 4 to 10 years for the socket
to burn out. Ah, and 220 V is almost 1/3 kV pk-pk ;).

Peter

1998\07\23@213829 by Harold M Hallikainen

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On Thu, 23 Jul 1998 13:36:25 +0200 Tjaart van der Walt
<EraseMEtjaartspam_OUTspamTakeThisOuTwasp.co.za> writes:
>Joe Lepine wrote:
>
>> The answer is IN the question.  The "live" leg has voltage on it
>> (arching).  The neutral is by definition at or near ground.
>
>I thought about this, but it is AC. Besides, how does this
>pin know it is close to ground and therefore not supposed to
>get hot?


       I wonder if the neutral pin makes contact first, so the hot pin
is the one that actually has to make or break the circuit (and arc).
Also, on 120 VAC plugs, the hot pin is narrower, perhaps increasing its
resistance.

Harold


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'[OT] 240V anywhere'
1998\08\19@055722 by Ed Arnold
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Tjaart van der Walt wrote:

> Why do heavy current appliances (220V over here)
> only burn the 'live' contact in the plug and not the
> neutral contact. It is AC, right?

Consider the 'Live' wire as an electrical inlet and the 'Neutral' wire
as an electrical return.   Your appliance asks for current which enters
through the 'Live' wire, uses the current up, and returns nothing out
the 'Neutral' wire.  If your appliance asks for more current than the
copper 'Live' wire can handle, then the 'Live' wire or connector burns.

I hope this clears this up

Ed Arnold
hilanderspamspam_OUTbellsoth.net

1998\08\19@061840 by Victor Moisey

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> Tjaart van der Walt wrote:
>
> > Why do heavy current appliances (220V over here)
> > only burn the 'live' contact in the plug and not the
> > neutral contact. It is AC, right?
>
> Consider the 'Live' wire as an electrical inlet and the 'Neutral' wire
> as an electrical return.   Your appliance asks for current which enters
> through the 'Live' wire, uses the current up, and returns nothing out
> the 'Neutral' wire.  If your appliance asks for more current than the
> copper 'Live' wire can handle, then the 'Live' wire or connector burns.
>
> I hope this clears this up
>
> Ed Arnold
> @spam@hilanderKILLspamspambellsoth.net
>

If neutral returns nothing then why have a neutral wire?


Victor Moisey
Institute of Child Health
Red Cross Childrens Hospital
Private Bag
Rondebosch 7700
Cape Town
South Africa

1998\08\19@065956 by

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> Tjaart van der Walt wrote:
>
> > Why do heavy current appliances (220V over here)
> > only burn the 'live' contact in the plug and not the
> > neutral contact. It is AC, right?
>
> Consider the 'Live' wire as an electrical inlet and the 'Neutral' wire
> as an electrical return.   Your appliance asks for current which enters
> through the 'Live' wire, uses the current up, and returns nothing out
> the 'Neutral' wire.  If your appliance asks for more current than the
> copper 'Live' wire can handle, then the 'Live' wire or connector burns.
>
> I hope this clears this up
>
> Ed Arnold
> KILLspamhilanderKILLspamspambellsoth.net
>
That is a very suspicious claim, you are saying that no current flows
through the neutral wire?  If that is the case on your appliances I'd check
your earth system out!  Appliances don't just "use current up", you can't
pour current down a wire and watch it go to nowhere, it has to exit back out
of the appliance from somewhere, and it's meant to be the neutral wire.  As
you correctly say, it is a return.

Mike Rigby-Jones
RemoveMEmrjonesTakeThisOuTspamnortel.co.uk

1998\08\19@070620 by Clyde Smith-Stubbs

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On Wed, Aug 19, 1998 at 12:14:58PM +0000, Victor Moisey wrote:

> If neutral returns nothing then why have a neutral wire?

Under some circumstances there is current returned via the neutral wire.
For example, if you were to place a block of dry ice in your refrigerator,
the 'fridge will have to operate in inverse mode to warm the ice up
to the preset temperature. This means it will return current via the neutral
wire, which will go back into the electricity grid.

Similarly, if you have a piece of toast in a toaster that catches fire,
it will heat the toaster instead of the other way around, this will
also cause current to be returned via the neutral wire.

In any case, many appliances that are not 100% efficient will always return some
current via the neutral since they take in more current than they actually
need. If you disconnect the neutral, the excess current backs up and stops
the appliance from working, since it cannot get rid of the excess current and
becomes clogged with electrons.

You could dump the excess current to ground, but the electricity authorities
do not like this (it's wasteful) - that's why they encourage you to install
earth leakage detectors.

Oh, and the other major need for it is when you switch a ceiling fan
to run backwards, for winter use, it will actually draw current via
the neutral wire instead of the active, because the motor is running
backwards.

Hope this helps.

Cheers, Clyde

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1998\08\19@103143 by Bob Blick

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On Wed, 19 Aug 1998, Clyde Smith-Stubbs wrote:
>
> Under some circumstances there is current returned via the neutral wire.
> For example, if you were to place a block of dry ice in your refrigerator,
> the 'fridge will have to operate in inverse mode to warm the ice up
> to the preset temperature. This means it will return current via the neutral
> wire, which will go back into the electricity grid.
>
> Similarly, if you have a piece of toast in a toaster that catches fire,
> it will heat the toaster instead of the other way around, this will
> also cause current to be returned via the neutral wire.

Those devices called "ground fault circuit interrupters" are designed to
prevent this by breaking the circuit. Electric power companies do not like
having power produced by anyone but themselves, so they lobby for the
installation of GFCIs, which are already required by electric code in many
circuits. The big lie is that it is for "protection". But whose
protection? I say it is to protect their profits, and prevent people from
reducing their electric bills with modified toasters and other such
devices.

:-)

Cheers,
Bob

1998\08\19@113219 by nick nelissen

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Bob Blick wrote:

{Quote hidden}

Do I detect some subtle leg pulling here 8-).

I'm not an electrician, but....

I should point out that in some countries the neutral is tied to earth, usually
at each fuse box.  Other countries don't do this.
So if you grab the "active" wire while standing on a damp concrete floor in
Australia you will get a zap. Where the neutral is not tied to earth you won't.

GFCI or residual current devices make sense here where neutral is tied to earth.
They operate on the principle that all the current in matches all the current
out, and that is switching back and forth at 60/50hz . Any current that doesn't
make it out is going to earth (where neutral is tied to earth) and this may be
through a human body so the device trips.

I found this out when I was working under my VW Kombi with a lamp on a lead and
I
caught the lead between the car and the engine mount ...  flash ... bang ...trip
.

Someone else may wish to explain how you get a neutral when you have three phase
distribution with no neutral wire.

Nick

1998\08\19@121128 by Ken

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I'll try to bring this back on topic...

So whatever happened to installing solar panels, gas turbines, wind
turbines, or whatever, and producing more power than you use?  I knew
several "frontier" types who did this, and I believe the law says the power
company has to buy the excess electricity if you dump into their grid.  I've
also read about some people running their meters backwards using this
approach (and some other hokey power generators and some knowledge of the
meter's properties - but we'll not go there), and winding up with a negative
power bill that way...

I've been toying with the idea of putting up both an "egg-beater" wind
turbine, and a bank of photovoltaic cells (I can do 5-10KV pretty easily
with very little loss - lots of wind and sunshine here in Oklahoma ;), and
selling the power back to the grid.  I've got GFCI outlets all over my
house.  Is my powerplant going to be tripping my GFCI outlets all the time?
I guess I should probably build a regulator with inputs from my own plant
and the power grid, which will automatically draw from the grid when needed,
and use my plant the rest of the time, and dump everything back into the
grid (after my batteries are charged, that is ;).

What do you think?  Sound like a good PIC application, or is that overkill
for a voltage regulator ;)

Ken



>> circuits. The big lie is that it is for "protection". But whose
>> protection? I say it is to protect their profits, and prevent people from

1998\08\19@123334 by Bob Blick

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On Wed, 19 Aug 1998, Ken wrote:
> selling the power back to the grid.  I've got GFCI outlets all over my
> house.  Is my powerplant going to be tripping my GFCI outlets all the time?
>
> Ken
>
> >> circuits. The big lie is that it is for "protection". But whose
> >> protection? I say it is to protect their profits, and prevent people from

Whoa, sorry, I took Clyde's joke and ran with it. You won't trip any GFCIs
by powering the grid. GFCIs are not a "secret government plot" :-) Except
for the little transmitters in them. :-)

-Bob

1998\08\19@161341 by n/a

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Clyde Smith-Stubbs wrote:
>
> On Wed, Aug 19, 1998 at 12:14:58PM +0000, Victor Moisey wrote:
>
> > If neutral returns nothing then why have a neutral wire?
>
> Under some circumstances there is current returned via the neutral wire.
> For example, if you were to place a block of dry ice in your refrigerator,
> the 'fridge will have to operate in inverse mode to warm the ice up
> to the preset temperature. This means it will return current via the neutral
> wire, which will go back into the electricity grid.

Clyde your resistors are in backwards! ;-}

--
Neil Cherry     http://home.att.net/~ncherry    RemoveMEncherryspamTakeThisOuTworldnet.att.net

1998\08\19@182927 by Dennis Plunkett

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At 07:24 AM 19/08/98 +0000, you wrote:
{Quote hidden}

Ah my kingdom for a power factor of 0 :-). Why not stop all your electrical
products from producting "heat", that would be easyer!.
Anyway what is this neutral stuff? I always thought that that black wire (Or
blue) was infact an earth return (Bonded to earth as the junction box in the
house, and then connected to local earth at the house which then feeds back
to the earth grid at the substation), or the centre of a star delta
generator (Via earth)? :-)

:-)
Dennis

1998\08\19@190037 by Tony Nixon

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I like to be 'active' on this list but I think I will stay 'neutral' on
this one. Keep both legs firmly on the 'ground' so to say.

--
Best regards

Tony

Multimedia 16F84 Beginners PIC Tools.
**New PicNPrac**

http://www.picnpoke.com
Email picnpokeEraseMEspam.....cdi.com.au

1998\08\19@190243 by Ken

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So, basically, the idea is to make sure that you are as near to 100%
efficient, and are returning no power to the grid.  Could a battery charger
operate at a high enough efficiency to be used as a sort of "mop" to make
sure that you aren't returning any power back to the grid?

It should only take a fairly simple circuit to sense the current draw at the
panel, compare that to the current on the neutral, and create an adequate
load "downstream" to drain the current to 0A.  Am I out of my mind?  (it
wouldn't surprise me - I understand DC much better than AC)

On a more humerous side - there are no-doubt agreements in place between the
util companies and the manufacturers of most electrical appliances to create
inefficient, wasteful devices, so that the consumer pays for X number of
electrons, but only uses 60% of them or so.

This may become a crusade :)

Ken

-----Original Message-----
From: Bob Blick <EraseMEbobspamTED.NET>
To: RemoveMEPICLISTEraseMEspamEraseMEMITVMA.MIT.EDU <RemoveMEPICLISTspam_OUTspamKILLspamMITVMA.MIT.EDU>
Date: Wednesday, August 19, 1998 9:35 AM
Subject: Re: [OT] 240V anywhere


<big snip>

:)

1998\08\20@195905 by Barry Cooper

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At 12:14 PM 19.8.98 SAST-2, you wrote:
{Quote hidden}

 It's a plot by the cable manufacturers to make people buy twice as much
cable. BTW you do need to be careful not to energize a cable that is not
connected to anything otherwise the electrons will fall out on the floor
and bite you when you step in them. (g)

       Barry

1998\08\20@221111 by Eric Smith

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Bob Blick <EraseMEbobspamspamspamBeGoneTED.NET> wrote:
> Those devices called "ground fault circuit interrupters" are designed to
> prevent this by breaking the circuit. Electric power companies do not like
> having power produced by anyone but themselves, so they lobby for the
> installation of GFCIs, which are already required by electric code in many
> circuits. The big lie is that it is for "protection". But whose
> protection? I say it is to protect their profits, and prevent people from
> reducing their electric bills with modified toasters and other such
> devices.

If you produce electricity and dump it back into the grid, it will not
trip your GFCI.  The GFCI only trips if the hot and neutral current aren't
balanced.  This is done to make sure the current isn't going somewhere else,
like through your person to ground.  The GFCI really is there for your
protection.  It's not a sinister conspiracy to boost their profits.

In general the utilities do not like you providing them with power.  But
the reason for this is also a safety matter.  If there is a power outage,
they don't want you putting power on the lines that they think are dead.

Most states allow (or even require) that you sell any excess electricity
you produce to the electric utility.  However, in order to do this you are
required to buy special switching equipment.  Note that there's a reason
why everyone isn't taking advantage of this and generating power for sale
back to the utility:  they only are required to pay your wholesale rates
for the electricity you sell them.  This is much lower than the retail rate
that they charge you.

Eric

1998\08\25@130930 by Gary Chung

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------------------------------------<snippped>-------------------------

> Someone else may wish to explain how you get a neutral when you have three pha
se
> distribution with no neutral wire.

1) You still need a neutral if your appliance works on a single phase.

2) If you appliance or equipments (motors, etc) works on three phase, you do not
   need a neutral as one of the phase or both shall act as a return for the cur
rent.

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