No Earth!

[sosh]

Hi,

I have a question relating to my flat in Poland. While replacing some of the mains sockets I realised (to my great suprise, since the flat was built in 1991) that there is no earth on any circuit!

The person who had installed the sockets had bridged the earth pin with the neutral pin, so the earth pin and neutral are at the same potential.

Don't get me started about the standard of electrical safety here. The sockets are of a very poor quality, mains wiring without colour coding is common, and as you see grounded earths are a luxury.

So this shocked me a bit, and I sat there scratching my head to think about the implications of connecting the earth pin to neutral. I couldn't really think of why it would be a terrible idea, but I had a feeling that it was, so I left the earth pins unconnected when I installed the new sockets.

Anyway, while looking on the web today I noticed this wikipedia entry about ground/earths. It states that the earth is normally connected to the neutral at some point in the network, and that under certain conditions it might even share the same wiring as neutral (which sounds a bit like what I've got). Here's the article:

http://en.wikipedia.org/wiki/Ground_(electricity)

Now I know that my installation would not be legal by UK standards, but forgetting the regulations for a moment - is this setup completely unsafe, or merely not recommended? What are my alternatives other than running in a new earth cable?

Thanks for your advice

 

[bernardgreen]

My personal opinion is that a separate earth system to all socket earth pins connected to an effective earth rod would go a long way to ensure that all appliances that need an earth do have an effective earth.

In the UK the use of the distribution neutral as the "earth" is reasonable safe as the standards for electrical distribution networks is high and the neutral is bonded to earth at the substation.

In other countries distributions standards can be much lower and the risk of a neutral floating ( disconnected from ground at the sub-station ) is higher than I would find acceptable. So reliance on the neutral as earth is something I would not trust.

If the earth system is taken from the neutral it should at one point as close to the incoming main as possible and an RCD should be fitted after that point. If the RCD is fitted between incomer and the junction of earth and neutral it will not trip on any fault other than maybe on a live to ground fault ( ground and not the earth wire ). Any fault to earth conductor will return the earth current back through the RCD on the neutral so there will be no detectable difference between live and neutral in the RCD.

 

[sosh]

OK thanks for your reply. So which in your opinion is better? This 'false earth' situation, or leaving the earth pin disconnected?

 

[bernardgreen]

OK thanks for your reply. So which in your opinion is better? This 'false earth' situation, or leaving the earth pin disconnected?

You need to take advice from the local electricity supplier and/or local electricians,. They may not be much help but worth a try.


And try to use only double insulated equipment as far as possible.

 

[Adam_151]

Not sure if it was ever proper practice, but from what I have heard, earth re-created from neutral at the socket, TNC style is far from uncommon in that part for the world

Personally like bernard I'd favor class 2 equipment and earth disconnected, however in the case of computers etc and other stuff that has filters its going to have to be tied down somewhere

Colour code when its used afaik is Black Phase, Grey Neutral and Red Earth, but I'd not be supprised if you said you had a bunch of whites!

EDIT: Apparently there is much worse outside of europe to paraphrase someone else on these boards, "The electrics do afterall, work, its just a bit of a mystery sometimes how no one actually dies"

 

[ColJack]

this is a TNC system and is not illegal by any means.. you can do it over here under certain circumstances.. and it is more likely overseas..

if your house has it's own transformer, generator, or you have permission from the supplier to use PEN conductors then you can..

my guess is that the flats have their own transformers as is more common abroad...

the neutral and earth only split at your cut out on most installations..

 

[plugwash]

I thought under the ESQCR TN-C was illegal in the UK except in a few very specific situations. No idea if its legal in poland though.

combined neutral and earth cores are tollerated under certain circumstances due to the cost saving but they require extreme care to be safe.

the problem is if the neutral breaks then the earth connection can become live which is bad. Combined neutral and earth connections also cannot be used after RCDs.

Personally i'd try to stick to class 2 equipment as much as possible and where there was little choice but to use class 1 equipment try and pull an extra wire in.