Who's rewired their house for this hobby?

Tor Arntsen kspt.tor at gmail.com
Wed Nov 26 02:49:50 CST 2014

On 25 November 2014 at 21:17, Eric Smith <spacewar at gmail.com> wrote:

> On the other hand, distributing three-phase to residences, while great
> for people with shop equipment or old computers, seems like expensive
> overkill for normal homes.

I don't know the reasoning for Germany, but in my town in Norway it
was apparently used in order to reduce costs, actually.
Traditionally 3-phase in Norway has been distributed with 3, not 4
wires: If balanced, earth return current is zero. Some years ago the
Norwegian system was unified with what's standard in most of EU, I'm
not sure if things changed then (but at least in the past there was no
'neutral' and 'live' in a home - both wires were equal in that
respect, and the voltage to earth was never 220V (as we used back
then, now it's 230V), it could vary but was in practice never more
than 160V, normally just 120V. Less of a jolt than if you touched both
wires. Wire to earth accidents is a much more common affair than
wire-to-wire accidents).

Anyway, I'm not an expert on this so as I said I'm not certain if the
policy of using only 3 wires has changed - but at least with that
system, distributing 3-phase means that you could transport 200% more
effect with only one additional wire. Even with four wires it pays
off. And that's why it was done AFAIK. [In addition it seems that
feeding 3-phase all the way to the consumer is nearly 'free' with TN,
see below]

(Reading up on this a bit - apparently the traditional Norwegian power
distribution system was called 'IT', Isolated Terra, while new and
refurbished areas are now using TN, Terra Neutral (400V), the system
which is now common in Europe.  What impact this has for the jolt when
you touch the wire I'm not sure about [update: Ouch, you'll get 230V
to earth], but apparently TN is what makes it feasible to distribute
3-phase to every house. With the older IT system the (then) 3-phase
380V system had to be installed separately. With TN you get both 230V
and 400V directly available for the consumer. But I think you'll need
4 wires in practice. It still pays off, economically.]

Now I slowly retract my steps back to the more familiar lower-voltage
DC land where I feel on more solid ground.. :-)


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