Newsgroups: sci.engr.electrical.compliance
Subject: Re: Non-standard domestic power sockets?
References: <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> 
[email protected] writes:

> On Tue, 07 Feb 2006 19:08:33 -0500 Mark T.B. Carroll  wrote:
> | [email protected] writes:
> | 
> |> It's very unlikely as UL and the other NRTL only normally test products to
> |> US standards.
> | 
> | Are there any US-certified sockets that could reasonably be expected to
> | bear 220V/neutral/earth on the three pins? Then I could plug a simple
> | adapter into it. (I wouldn't want to put in a regular domestic 220V
> | socket wired in the UK way as I wouldn't want to surprise people who
> | quite reasonably expected 110V/neutral/110V out of it.)
> 
> There could be issues both ways.  Appliances brought in from UK would
> surely expect at least 240 volts plus variance between line and neutral
> and so could handle that fine.  But given the UK socket is polarized so
> a specific wire is certainly neutral, there could be a case of hazard
> if that wire is supplied with voltage well above ground level.  One
> example would be a light bulb socket in the appliance that uses an
> Edison style screw base (I really have no idea if these could be used
> in UK or not) where a human could readily contact the neutral base.
> 
> The CEE 7 socket as found in Germany, however, has no polarity to it.
> You can plug in two ways, 180 degrees rotated, and have correct contact
> and grounding.  I'll guess this and the ungrounded plug version originally
> came from the 127/220 volt system I understand once existed in Europe
> (and presumably line-to-line connections became the preferred standard).
> A friend in .de told me all appliances must be made so they are safe
> regardless of which way they are plugged in.  

That is true. 

> He added that Edison style
> screw base bulb sockets were not permitted in a pluggable appliance since
> reversed plugging could leave the threaded base part that can be touched
> at a 230 volt to ground potential.  

I live in Finland. Edison type bulb sockets can be used on 
pluggable appliances here and have been used on many appliances. 
The need for the design of those is so that they must be designed 
in such way that you can't touch the metal base part of the bulb 
or base when the lamp is screwed plugged. So when there is 
lamp in the base, there is no danger that eanyone can touch 
the base part that could be potentially dangerous. 
The base designs are made so that this need is fulfilled. 
Many cheap lamps based have the scre part mad of plastic, 
and there is just a spring at nearly bottom of the base 
that touches the metal threads on the lamp.. 
This is often seen on modern pluggable lamps. 
You can see metal threads on the lamp base on fixed lighting 
instruments (with those you know which part is live or neutral). 

> He described bi-pin bulbs as the ones
> typically used.  

Bi-pin bulbs haev not been traditionally used much in Finland. 
But nowadays they can be seen on some newer lamps... 

> I had originally asked him about running computers on
> the USA style 240 volt system where each line is 120 volts to ground, and
> he said any power supply that meets German standards would have to work
> since it would have to assume either line could be as much as 220 to 240
> volts relative to ground.  A few weeks ago when a power supply of mine
> died, I disassembled it and confirmed the rear AC cutoff switch was of
> the 2 pole variety, shutting off both wires at the same time (which were
> colored brown and blue).
> 
> Basically, I suspect most appliances designed to function correctly and
> safely in Germany, with a CEE 7/7 plug attached, for use on a CEE 7 socket,
> would be safe in the USA on 240 volts, provided they don't have an issue
> with the 60 Hz power frequency.  

That should be the case. There are some locations inside Europe 
(for example certain locations in Norway) where the mains outlet 
(CEE 7/7 soekect or somethign similar grounded/ungrounded) 
does not have this raditional live+neutral wiring. Instead of that 
the outlet gets wired from two phases of three phase power where 
there is 230V AC between phases. 

From: http://www.epanorama.net/links/wire_mains.html#europe
Other special cases: There are also some special wiring used in some
places. Another much rarer scheme is 230V between phases and no
neutralin the supply (also called 230V delta). Houses are then fed two
phase wires, neither of which is necessarily anywhere near earth
potential. This is used in at least in Norway in some locations. Also
in some places in Belgium three phase 220 across the phases (= 127
phase to earth/neutral, 230V Y output on transformer) is used on older
domestic dwellings (new installations are 400/230V 3 phase, neutral,
earth). For this reason all Belgian fuseboards (whether actual fuses
orcircuit breakers) protect both current carrying wires irrespective
of supply type. 

> But British appliances, and others of a
> number of other countries that have polarized sockets, might not (but then,
> they could be unsafe in Germany, too).

Could be in some cases. 

> There is also a 60-0-60 system in the US, intended primarily for technical
> power for avoiding ground issues with audio equipment.  It is considered
> unsafe to plug in regular 120 volt appliances to this kind of power since
> both line wires are 60 volts relative to ground.  While 60 volts is not
> the jolt you'd get from 120 or even 230, it can still be enough to kill in
> some cases, or cause some poorly designed equipment to malfunction and
> maybe even be a fire hazard.  I bring this up because it is typical of the
> kinds of issues that can exist when assumptions are made about voltage to
> ground levels of power conductors.
> 
> -- 
> -----------------------------------------------------------------------------
> | Phil Howard KA9WGN       | http://linuxhomepage.com/      http://ham.org/ |
> | (first name) at ipal.net | http://phil.ipal.org/   http://ka9wgn.ham.org/ |
> -----------------------------------------------------------------------------

-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/