Question for Finnish Tech people (Electrical engineering)

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CityBird
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Joined: Wed Jan 11, 2017 1:23 pm

Question for Finnish Tech people (Electrical engineering)

Post by CityBird » Wed Jan 11, 2017 1:44 pm

Hope someone can help me with some electrical engineering questions. Unfortunately international Tech Forums don't give me any conclusive answers and my Finnish isn't goed enough to involve myself in native Finnish tech forums :) .

I understand that the mains supply system in Finland differs considerably from most of Europe. Could someone clarify these.

- Most 3-phase supply is 3x230V without neutral?
- Do (some) homes get 3-phase supply or always just one single phase?
- How does the grounding with you guys work. Is this one transformer leg (delta) connected to ground (230,230,0 V with respect to ground) or Wye centre tap connected to ground (130,130,130V with respect to ground) or is this a so-called IT-system (floating) with (or without?) GFCI. If so how do residents monitor earth failures?

Thanks



Question for Finnish Tech people (Electrical engineering)

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Jukka Aho
Posts: 5238
Joined: Fri Apr 06, 2007 1:46 am
Location: Espoo, Finland

Re: Question for Finnish Tech people (Electrical engineering

Post by Jukka Aho » Thu Jan 12, 2017 12:14 am

CityBird wrote:Hope someone can help me with some electrical engineering questions. Unfortunately international Tech Forums don't give me any conclusive answers and my Finnish isn't goed enough to involve myself in native Finnish tech forums :) .

I understand that the mains supply system in Finland differs considerably from most of Europe. Could someone clarify these.

- Most 3-phase supply is 3x230V without neutral?
- Do (some) homes get 3-phase supply or always just one single phase?
- How does the grounding with you guys work. Is this one transformer leg (delta) connected to ground (230,230,0 V with respect to ground) or Wye centre tap connected to ground (130,130,130V with respect to ground) or is this a so-called IT-system (floating) with (or without?) GFCI. If so how do residents monitor earth failures?
Not an expert in this field, but in short, Finland uses the TN–C–S system for electrical supply to normal households and offices. It is typically three phases + PEN into the home, but the PEN is then split into PE and N in the fixed indoor wiring and subsequent extension cords. Each phase is 230V against ground, 400V against each other.

In older installations, the wall sockets only used to have the protective earth contacts if located in a potentially damp environment, such as a bathroom, or outdoors, or in a non-insulated outbuilding. Any new installations have PE on every socket. The old PE-less sockets are of the CEE 7/1 type and the ones with PE are CEE 7/3, the same type as used in Germany.

The three phases are typically split into separate (groups of) rooms in the house, so that you will have some rooms connected to L1, some to L2 and so on.

The electric range/range top/oven, the HVAC components, and the sauna stove are typically connected to three-phase power using fixed connections hidden in a wall box. You might additionally have some 400V IEC 60309 outlets for three-phase power — for powering some heavier-duty workshop tools such as table saws, band saws and lathes. Electric cars will also likely increase the use and installation of three-phase power sockets in regular households but they have varying plug standards.

Alternatively, you might only get a single phase + PEN if it is an old, small house (or apartment) where your great-granny used to live — but then it has to be quite old, small, and neglected (not renovated lately), or something like a summer cottage where your needs are met with less and the installation was cheaper that way. Three-phase to the home is the normal way in modern times.

If you know any Finnish or can machine-translate some, this discussion might be of some interest to you:

https://groups.google.com/forum/#!topic ... 19mXV7us3I

Some pictures of residential fuse boxes:

An old one in an old rural home, maybe installed in the 1950s or 1960s:

http://3.bp.blogspot.com/_EtYpxyIfjwI/S ... G_2680.JPG

Bit larger ones, probably of the same age but with a modern meter:

http://www.ess.fi/incoming/2015/06/09/1 ... 244518.jpg

This one has suffered some wear and tear (taken from a blog where a couple is renovating an old house.) Note the three main fuses in the bottom-left corner, one for each phase:

http://1.bp.blogspot.com/-3MamRa8vJxE/V ... CF4717.JPG

More modern samples from the 1980s or so:

http://www.eltelnetworks.com/globalasse ... roject.jpg

http://images.cdn.yle.fi/image/upload// ... 650208.jpg

A modern fusebox with automatic circuit breakers (from my own apartment built in 2002):

http://imgur.com/a/22gDJ

Another one which is being installed to someone’s new home at the time the picture has been taken:

http://www.viitalat.net/media/20060123_1.jpg
znark


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Piet
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Joined: Thu Aug 13, 2015 3:45 pm
Location: Finland

Re: Question for Finnish Tech people (Electrical engineering

Post by Piet » Thu Jan 12, 2017 11:11 am

CityBird wrote:Hope someone can help me with some electrical engineering questions. Unfortunately international Tech Forums don't give me any conclusive answers and my Finnish isn't goed enough to involve myself in native Finnish tech forums :) .

I understand that the mains supply system in Finland differs considerably from most of Europe. Could someone clarify these.

- Most 3-phase supply is 3x230V without neutral?
- Do (some) homes get 3-phase supply or always just one single phase?
- How does the grounding with you guys work. Is this one transformer leg (delta) connected to ground (230,230,0 V with respect to ground) or Wye centre tap connected to ground (130,130,130V with respect to ground) or is this a so-called IT-system (floating) with (or without?) GFCI. If so how do residents monitor earth failures?

Thanks
Little addition to Jukka Aho his information (nice summary by the way :wink: )

I have seen multiple installations in Finland and to my horror, lots are not up to required standards. (wire colours not as they should like black for switching, or black numbered with L1, L2, L3 for 3 phase connections, brown for single group phase, blue for the Neutral or 0, and green-yellow for ground / Earth).

In lots of cases one can find the PE connected directly to N, which is a deadly sin where I come from, but always better than to leave it unconnected (seen that too).

PE from the wall sockets should always be connected to the PE protection switch which will typically cut off all electricity for the protected group when a leak current to Earth is detected of more than 15 - 30mA.
This is how residents monitor earth failures, the Electricity will cut off :lol:
Most common groups to be protected by this switch are the bathroom, kitchen and any outdoor sockets (as we say "Wet" groups).

Image

or an older one

Image

For older houses that did not have PE or this was connected to N, this should be changed by the creation of a real PE by drilling a hole in the ground that reaches the ground water deep enough to guarantee grounding, place a copper pipe in there and this will be the PE connection where all water piping (if still copper) will be grounded too as will the electrical installation.
If god would give us the source code, we could change the world
Image


Jukka Aho
Posts: 5238
Joined: Fri Apr 06, 2007 1:46 am
Location: Espoo, Finland

Re: Question for Finnish Tech people (Electrical engineering

Post by Jukka Aho » Thu Jan 12, 2017 7:01 pm

Piet wrote:I have seen multiple installations in Finland and to my horror, lots are not up to required standards. (wire colours not as they should like black for switching, or black numbered with L1, L2, L3 for 3 phase connections, brown for single group phase, blue for the Neutral or 0, and green-yellow for ground / Earth).
The thing about wire color standards is, they have changed them over the years.

Here’s some information on both the current regulations and the older practices which are described at the bottom of the page (Vanhoissa asennuksissa (ennen vuotta 1974) käytettyjä johdinvärejä):

http://www2.amk.fi/digma.fi/www.amk.fi/ ... 26704.html
Piet wrote:In lots of cases one can find the PE connected directly to N, which is a deadly sin where I come from, but always better than to leave it unconnected (seen that too).
Just to clarify, those are old or upgraded-at-one-point-but-not-really-rewired installations. Shouldn’t be the case for any new (from scratch) wiring.
Piet wrote:PE from the wall sockets should always be connected to the PE protection switch which will typically cut off all electricity for the protected group when a leak current to Earth is detected of more than 15 - 30mA.
This is how residents monitor earth failures, the Electricity will cut off :lol:
Yeah, quite sensitive those are, too. I was peeling off old wallpaper which had to be sprayed damp with fine water mist and suddenly realized electricity had been automatically cut off from the room because (apparently) a teeny amount of moisture had entered the wall sockets. (There were no visible droplets or puddles, just general dampness on the wall.)
Piet wrote:For older houses that did not have PE or this was connected to N, this should be changed by the creation of a real PE by drilling a hole in the ground that reaches the ground water deep enough to guarantee grounding, place a copper pipe in there and this will be the PE connection where all water piping (if still copper) will be grounded too as will the electrical installation.
A Google search with illustrations:

https://www.google.fi/search?q=maadoitu ... i&tbm=isch

See, for instance:

http://www2.amk.fi/Ensto/www.amk.fi/opi ... 45110.html
znark


CityBird
Posts: 2
Joined: Wed Jan 11, 2017 1:23 pm

Re: Question for Finnish Tech people (Electrical engineering

Post by CityBird » Thu Jan 12, 2017 9:38 pm

Thanks a lot,

Plenty of information to read through :D


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