ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades Norwegian power?

Not sure what system you ask about.

We have 2 systems in Norway today:

1)A 230/400 V system equal to UK systems.
2)A 230/230 V system where single phase loads are between 2 legs of the 230V 3 phase system. This may or may not have a grounded center of the Y (IT or TT) no Neutral wire at all.

As far as I know this was banned in the UK from 1948.

By experience I may tell touching a single live wire standing on a surface of a PVC floor are at least unpleasant :-)

If the PVC floor is fairly thin, and the sub floor even slightly conductive then capacitive coupling will ensure enough current to feel it. Also any surface film of condensation will make the floor a less than perfect insulator.

I can confirm that! Even wearing shoes with rubber soles and standing on a wooden floor a 230 V sgock is rather unpleasant! I got bit by a portable record player on a flea market, that's how I know. Of course the floor may have been a bit damp as this happened in a cellar but still, I had an inch of rubber or so between my feet and the floor!

Speaking of ungrounded outlets, a few months ago I got to tour an untouched 1910s apartment (now a museum) and in the bathroom there was an outlet right next to the sink!

Hi dsk with the 230 volt system presumably you get 230 phase to phase and 127 volts to earth/neutral is this right? On another topic I remember that when I'm upstairs standing on carpet which is on wooden boards I can touch live 240 volt terminal and feel nothing but if I accidently touch a wall I get a slight tingle.

You are right usually close to 127V to ground, but i may drop to 0 if its a fault somewhere, or raise to 230. Sometimes it is much higher voltages to, or peeks, but it is a sort of fusing in the transformer center who shorts to ground if to high voltage. (at least more than 230)

I know a student who did the trick mentioned over, because it was a fault somewhere outside his apartment, so he had 230 to ground. He just removed one fuse (the metered leg), and linked the ground to the disconnected wire. That way he could get 10 amps "free".

Regarding feeling the voltage. The caretaker at the old STK (=STC) in Oslo didn't like to climb the ladder so he always tried with his fingers if it was OK before he put in an an lamp. :-) (about 1970)

More or less. Since you don't have a fixed reference to earth (or only a high-impedance connection) in an IT network the actual voltage will vary a bit.

BTW, it's 133 V these days, not 127 (127 is 220 V*sqrt(3) and 133=230*sqrt(3))

Thanks yes I knew 127 was for 220 phase to phase but I always struggle with the maths thanks for the info its been most helpful

No problem!
I read about it so often that I've really learned those voltages by heart, that's why I notice such inconsistencies.

I think the big issue with maths is who becomes a teacher. Naturally people who hated maths because they had a hard time understanding it are quite unlikely to study it and become teachers. Unfortunately that means most teachers don't realise what it feels like to be "mathematically challenged" and what those who are need.

I tried studying electrical engineering for two painful semesters... worst time of my life! Few people have ever been as successful making me feel dumb as those maths geniuses! Later I switched to a more basic course (non-academic) and passed with flying colours. I can do maths when I need it and someone explains it to me in a way I understand but otherwise I'm lost.

I did not think about that difference, we still say 380 for 400, 220 for 230 etc here. In this discussion are this just of academic interest. If you tell people it is the phase voltage divided with the square root of 3, most people just say yes OK. (but get no interest)

If you draw a triangle of with sides of 230, put in a Y and measure to the center they may even understand it.

(I have teaught this on a modest level)

IMO 230 volts TN should be used in all domestic and light commercial, its much safer and no broken neutral to worry.

Ive always wondered, why was IT chosen over TN? Surely grounding the neutral would have been better?