Mains Neutral and Earth connected.

[potcore]

Hello,

I have just designed an SMPS for bench use at work and was thinking about Earthing the chassis. However, when i metered the mains socket outlets i found that Mains Earth and Mains Neutral are connected together.

Does anybody know if this is supposed to be so?

I thought that any current in the earth wire was generally a bad thing.

Also, in relation to this, i wondered if anyone knows of a link for the circuit diagram from power station turbine output , right up to household mains socket? -I can't find it wherever i search. -Hopefully it would show all earth connections and transformers.

Anyway, i suppose for my place, common_mode_current and differential_mode_current are one and the same thing....does that mean i dont need any common mode filters?, e.g. those "balancing transformer types", where N1I1 = N2I2.

 

[davidbeach]

Neutral is grounded at one point only. The only current flowing in ground is fault or leakage current. I'm not sure I understand your concern about neutral and ground being at the same potential.

 

[Skogsgurra]

There are a lot of configurations for the voltages arriving at the wall socket.

The one you have is a TN, probably a TN-C, aka four wire system. There are also TN-S systems, or five wire systems. In both cases the PE and N are connected together. And shall be so.

There are also IT systems. They have no neutral. So there is no N that can be connected to PE. And TT systems. Common in the US. I have never met one of those. At least not that I know about.

Gunnar Englund

http://www.gke.org

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