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-   -   Polish flat - No earth! (http://www.diychatroom.com/f18/polish-flat-no-earth-9756/)

Sosh 07-09-2007 09:05 AM

Polish flat - No earth!
 
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_%28electricity%29

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!

Stubbie 07-09-2007 02:55 PM

I have no clue what is required in Poland but in the USA this is called a bootleg ground and is quite dangerous given the correct set of circumstances.

Here in the US you would get the hair up on your inspector if he discovered this had been done to the receptacles.

You commonly see this done by unknowledgable homeowners or handymen when they want to install 3 prong receptacles on old wiring that has no ground and 2 prong receptacles. They think this provides a ground fault path by using the neutral wire (since they have no ground wire) They do this by installing a jumper from the ground screw to the neutral screw. Unfortunately they don't realize they have connected to a current carrying wire. What they have done is provided a pathway for neutral current to travel into the ground wire of the power cord of anything plugged into that receptacle and it travels up to the metal frame of the appliance you plugged in. This is double double dangerous if the neutral ever opens on a fault condition.... then this jumper becomes the only path for neutral current. So it builds on the metal frames of appliances that are plugged in waiting for someone to do things just right and give it a path to ground, Such as touching your metal framed electric mixer and the kitchen sink or faucett. Now it uses you to get to ground and your toast.

Homeowners and landlords also do this to try and fool home inspectors that the house has grounded wiring. When they stick their receptacle testers into the 3 prong receptacle it will falsely indicate there is a ground, when in reality there isn't one. The three prong receptacle should not have been installed. The jumper to the neutral fools the tester.

However I have no knowledge of the electrical distribution methods in Poland, so check with someone local on this issue. I can't off the top of my head see what was done to your receptacles there is good.

In the USA the place where neutral and equipment ground (earth if you like) come together is at the dwelling service main panel. This is because they both must share the service entrance neutral wire to get fault current and neutral current back to the transformer. There is no ground wire with the service entrance.

Sosh 07-10-2007 05:18 AM

Ok thanks for your advice. So which is the lesser of two evils in your opinion? The false ground situation, or leaving the ground pin on the recepticle disconnected?

Stubbie 07-10-2007 12:49 PM

No question... disconnect it. Equipment ground should never be connected at receptacles to current carrying wires.

Stubbie


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