> >First, to get common names:
> >Hot = one Phase
> >Neutral = Protective Ground
> >Ground = Ground (the starpoint on 3 phases connected to earth at the
> 'generator')
> That explains the confusion. In the US:
> Hot is one phase and in single phase systems you can and do have 2 hots.
> Neutral is what you are refering to as ground. The starpoint for both
> single and 3 phase.
> Ground is the protective / frame ground.
Sorry, just my translation problem, I had to assign names where no
dictionary could help me, And Neutral = Protective Ground vs Ground
seemed to be logical - sorry.
> The protective ground (ground in US codes) is not allowed to normally carry
> any current.
Same over here.
> >Second, do I understand that US appliances got fuses on both wires
> >and both are switched ?
> On 240 volt equipment yes.
Ahh ja - we also use fuses in each 'Hot' wire - so if you have a
3~ installation, 3 fuses are to be installed _and_ they have to
be tied (mechanical), so if one blows all 3 will go off.
> >Over here in Germany only one wire is
> >switched and protected with a fuse, althrough it is not defined
> >which one is the 'hot' line, since our connector is symetrical
> >- there is no way to insert the plug in a way where the Hot and
> >the Ground side is defined - Our plug isn't inherited from the
> >DC times, but rather a new design when 220V AC became standard
> >in the 30s, to fit the needs of (and only of) AC Eq.
> The US did not used to make a distinction between hot and neutral until
> about 30 years ago when they added the "protective" ground pin. Now they
> are keyed. If you look closely at a receptacle, one blade is wider -
> neutral, The narrower blade is Hot and the round pin is protective ground.
> Some "equipment" uses only 2 wires. The blades and often one is larger to
> assure that it is polarized correctly. These polarized plugs have come into
> common usage in the last 20 years.
Strange, but common - I don't know any reason why the system has
to be keyed, I always assumed the US development of keyed plugs
was triggered by old DC systems (since in DC Eq. it is necersarry
to know the orientation), but not a new addition. Strange, we
dropped all orientationwhen switching to AC (with Protective
Ground). Could anyone give give a reason why the system has
to be keyed _IF_ a Protective Ground is included (other than
define the Protective Ground pin) ? Because, without Protective
Ground a definition of Neutral is essential, but with, no longer.
I'm realy courious, since this is the kind of technology I'm
originated - I studied Starkstromelektronik (Power Electronics)
after (high)school.
Thanks
Hans
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Received on Tue Apr 20 1999 - 13:31:55 BST